WO2012114370A1

WO2012114370A1 - Combustion device

Info

Publication number: WO2012114370A1
Application number: PCT/JP2011/000976
Authority: WO
Inventors: 越智佑介; 倉増公治; 木山研滋; 岡▲崎▼洋文
Original assignee: バブコック日立株式会社
Priority date: 2011-02-22
Filing date: 2011-02-22
Publication date: 2012-08-30
Also published as: CA2827903A1; PL2679899T3; KR101582729B1; KR20140008407A; EP2679899A4; JPWO2012114370A1; AU2011360560B2; US20130340659A1; EP2679899A1; EP2679899B1; CA2827903C; JP5743115B2

Abstract

Provided is a boiler having multiple burners (19) arranged on a furnace wall (10) of a furnace (18), each burner (19) comprising: a cylindrical fuel nozzle (3) for injecting a mixture of fuel and carrier gas therefor into the furnace (18); one or more cylindrical air nozzles (8, 11) provided on the outer circumference of the nozzle (3) for injecting combustion air into the furnace; and a wind box (12) for supplying combustion air to the nozzles (8, 11) in common. The wind box (12) is provided with openings (12a, 12b) through which combustion air flows in from a direction perpendicular to the axial direction of the burner (19), and is partitioned by a partition wall (14) to form multiple parallel flow paths for the air flowing in through the openings in a translational manner. Some of the multiple flow paths are connected to an upper part of the combustion air nozzle (8), and the remaining flow paths are connected to a lower part of the nozzle (8). Each of the multiple combustion air flow paths is independently provided with an air momentum deviation damper (15) and an air flow rate adjustment damper (17), such that the direction of the flame of the burner (19) can be changed between upward and downward directions inside the furnace (18) depending on a combustion condition such as a load.

Description

Combustion device

The present invention relates to a combustion apparatus such as a pulverized coal burning boiler having a pulverized coal burner.

In the combustion method using the pulverized coal burner of the pulverized coal fired boiler, in order to reduce the emission amount of nitrogen oxide (hereinafter referred to as NOx) in the combustion exhaust gas, the fuel is burned in a state of air shortage and then completely burned. A two-stage combustion method that supplies air for use from an after-air port is applied.

In order to further reduce the NOx concentration in the exhaust gas at the outlet of the boiler furnace, the following means can be used.

(1) The furnace installation position of the after-air port is increased, and the residence time of the combustion gas is increased while reaching the NOx reduction zone between the burner and the after-air port.

(2) The thermal excess ratio (input air amount / theoretical air amount) is reduced as much as possible to reduce the thermal NOx as compared with the prior art.

However, in the technique of (1) above, the complete combustion zone shifts to the downstream zone of the furnace (upper part of the furnace), and for (2), the combustion temperature increases as it approaches the theoretical air amount. Therefore, the exhaust gas temperature at the furnace outlet rises. For this reason, the steam temperature and the metal temperature of the rear heat transfer surface of the boiler rise, and in the design in which the heat transfer surface material, the heat transfer surface arrangement, etc. are kept as before, there is a high possibility of tube leak. Therefore, there is a problem that the design temperature of the rear heat transfer surface has to be higher than before, and it is necessary to improve the quality of the material from the viewpoint of strength and heat resistance.

NOx reduction measures that increase the residence time of the combustion gas from the burner to the NOx reduction zone in the furnace of the after-airport or reduce the excess air ratio (input air amount / theoretical air amount) than before. In order to make the design temperature of the rear heat transfer surface the same as the conventional one, it is conceivable that the flame direction of the burner can be varied in the vertical direction of the furnace according to the combustion conditions such as the load. That is, if the burner flame is directed downward and the residence time of the combustion gas in the NOx reduction region between the burner and the after-airport is increased, the furnace installation position of the after-airport may be the same as the conventional one. Even if the combustion temperature becomes high, the position is on the lower side (upstream) side in the furnace than before, so the exhaust gas temperature at the furnace outlet can be made equal to the conventional one.

Japanese Unexamined Patent Application Publication No. 2008-121924 discloses a burner having a movable nozzle. When the nozzle is made movable in such a portion of the radiant heat that faces the furnace, it is necessary to consider the damage caused by the fall of the clinker adhering to the furnace and securing the mobility.

Japanese Patent Application Laid-Open No. 2002-147713 discloses a burner that changes the direction of the flame (combustion region) by giving a deviation to the air flow rate in the circumferential direction of the burner.
In the burner having the combustion air nozzle having at least two air inflow directions shown here, the combustion air flow paths of the plurality of burners are connected by ducts on the outer wall of the furnace, and a common wind box is provided. This complicates the handling of the duct.

JP 2008-121924 A JP 2002-147713 A

As described above, when the burner having a movable nozzle described in Japanese Patent Application Laid-Open No. 2008-121924 is used, the clinker adhering to the furnace when the nozzle is made movable at a portion where the radiant heat is large facing the furnace. It is necessary to consider the damage caused by the fall of the camera and the securing of mobility.

In addition, the burner having the combustion air nozzle having at least two air inflow directions described in JP-A-2002-147713 also has a common combustion air flow path for each of the plurality of burners on the furnace outer wall as described above. In order to connect with a duct, the handling of the duct becomes complicated.

An object of the present invention is to provide a combustion apparatus in which the design temperature of the rear heat transfer surface can be made equal to the conventional one by changing the direction of the flame of the burner in the vertical direction in the furnace according to the combustion conditions such as the load. .

The above problem is solved by the following solution means.
According to the first aspect of the present invention, a cylindrical fuel nozzle 1 for injecting a mixture of fuel and its carrier gas into the furnace 18 and a combustion gas provided on the outer periphery of the fuel nozzle 1 are injected into the furnace 18. A plurality of burners 19 having one or more cylindrical

combustion gas nozzles

8 and 11 and a wind box 12 for supplying combustion gas to the

combustion gas nozzles

8 and 11 are arranged side by side on the furnace wall 10 of the furnace 18. In the combustion apparatus, the wind box 12 has combustion gas inflow openings 12a and 12b through which combustion gas flows from one direction perpendicular to the axial direction of the burner 19, The combustion gas inflow openings 12a and 12b are partitioned so as to form a plurality of parallel flow paths through which the combustion gas flows in parallel, and some of the plurality of flow paths are the combustion channels. Gas nozzle 8 11, the remaining flow path is connected to the lower side of the

combustion gas nozzles

8, 11, and a first flow rate adjusting means 15 for independently adjusting the flow rate of the combustion gas is provided in each of the plurality of flow paths. It is a combustion apparatus characterized by being provided.

According to a second aspect of the present invention, one duct 16 for supplying combustion gas to the plurality of window boxes 12 from the outside of the furnace 18 is installed outside the furnace wall 10 where the window box 12 is installed. The combustion apparatus according to claim 1.
A third aspect of the present invention is the combustion apparatus according to the first or second aspect, wherein a plurality of the wind boxes 12 are installed side by side inside or outside the one duct 16.

According to a fourth aspect of the present invention, the second flow rate adjusting means 17 for adjusting the flow rate of the combustion gas flowing into each burner 19 upstream of the first flow rate adjusting means 15 is provided in each window box 12. The combustion apparatus according to any one of claims 1 to 3, wherein the combustion apparatus is provided.

In the combustion apparatus of the present invention, each of the plurality of

combustion gas nozzles

8 and 11 is provided with the first flow rate adjusting means 15 for adjusting the flow rate of the combustion gas, so that the first flow rate adjusting means 15 is opened. By adjusting the degree, the momentum of the combustion gas ejected from the burner 19 into the furnace can be adjusted independently. For example, by adjusting the first flow rate adjusting means 15, the amount of air flow from the

combustion gas nozzle

8 or 11 into the furnace 18 is increased compared to the upper side of the burner 19, and the momentum (air jet flow rate) from the lower side is increased. By doing so, the flame can be deflected downward. By deflecting the flame downward, the maximum heat load region in the furnace 18 shifts downward, the heat absorption of the furnace 18 increases, and the furnace outlet exhaust gas temperature can be reduced. Further, by deflecting the flame below the burner 19 to shift the combustion area of the burner 19 downward, the inside of the furnace 18 between the burner 19 and the after air port 24 provided on the furnace wall 10 on the downstream side of the burner 19. The residence time in the NOx reduction zone at is longer than that when the flame ejection direction is horizontal, and the NOx concentration in the exhaust gas is reduced as compared with the prior art.
Further, by providing the second flow rate adjusting means 17 on the upstream side of the first flow rate adjusting means 15, the amount of air supplied to the individual burner 19 can be adjusted.

According to the first aspect of the present invention, the combustion gas jetted from the burner 19 into the furnace 18 is deflected in the vertical direction so as to deflect the flame and control the heat absorption of the furnace. As a result, the temperature control device for the rear heat transfer surface of the furnace 18 can be reduced. In addition, when modifying an existing combustion apparatus, a NOx reduction technique can be applied by changing the after-air port installation position and the excess air ratio without changing the steam temperature and metal temperature of the rear heat transfer surface. In addition, the combustion area of the burner 19 is shifted downward by deflecting the flame downward in the furnace 18, and the residence time in the NOx reduction area between the burner 19 and the after-air port 24 is set to the horizontal direction of the flame ejection. The NOx concentration in the exhaust gas can be reduced as compared with the conventional case by making it longer than that in the case of the above.
According to the second aspect of the present invention, in addition to the effect of the first aspect, the combustion gases supplied to the wind box 12 provided outside the furnace wall surface 10 are collectively supplied from one duct 16. Thus, the combustion gas supply system to the plurality of burners 19 can have a simple structure.
According to the invention described in claim 3, in addition to the effect of the invention described in

claim

1 or 2, a plurality of the windboxes 12 are arranged side by side outside the furnace wall 10 inside or outside one duct 16. This simplifies the construction of a plurality of wind boxes 12 and ducts 16.
According to the fourth aspect of the present invention, in addition to the effect of the first aspect of the present invention, the upper and lower combustion of the burner 19 is achieved by the first flow rate adjusting means 15 provided in one wind box 12. The amount of combustion gas supplied to the individual burners 19 can be adjusted by providing the second flow rate adjusting means 17 upstream of the first flow rate adjusting means 15. Can be easily done.

It is the schematic which shows the pulverized coal boiler system by this invention. It is a pulverized coal burner sectional view concerning one example of the present invention. FIG. 3 is a perspective view (FIG. 3A) of a wind box according to an embodiment of the present invention and a diagram showing a wind tunnel test result relating to the wind box (FIG. 3B). FIG. 3 is an example of a window box taken along the line AA in FIG. 2 (FIG. 4A) and the cross section taken along the line BB in FIG. 2 (FIG. 4B). FIG. 3 is an example of a window box taken along a line AA in FIG. 2 (FIG. 5A) and a cross section taken along a line BB in FIG. 2 (FIG. 5B). It is a figure which connects the wind box concerning one Example of this invention with the duct for combustion gas conveyance, and shows the supply method of combustion air. It is a figure which shows the supply method of the combustion air by installing the wind box concerning one Example of this invention in the duct for combustion gas conveyance. It is an example of the window box of the AA sectional view of FIG. It is an example of the window box of the AA sectional view of FIG. It is a figure which connects the wind box concerning one Example of this invention with the duct for combustion gas conveyance, and shows the supply method of combustion air. It is a figure which shows the supply method of the combustion air by installing the wind box concerning one Example of this invention in the duct for combustion gas conveyance. It is an example of the window box of the AA sectional view of FIG. It is an example of the window box of the AA sectional view of FIG. It is a figure which connects the wind box concerning one Example of this invention with the duct for combustion gas conveyance, and shows the supply method of combustion air. It is a figure which shows the supply method of the combustion air by installing the wind box concerning one Example of this invention in the duct for combustion gas conveyance. FIG. 3 is an example of a window box taken along the line AA in FIG. 2 (FIG. 16A) and the cross section along the line BB in FIG. 2 (FIG. 16B). 2 is an example of a window box taken along the line AA in FIG. 2 (FIG. 17A) and the cross section along the line BB in FIG. 2 (FIG. 17B). It is a figure which shows the supply method of the combustion air by installing the wind box concerning one Example of this invention in the duct for combustion gas conveyance. It is a figure which connects the wind box concerning one Example of this invention with the duct for combustion gas conveyance, and shows the supply method of combustion air.

1 shows a pulverized coal boiler system according to the present invention, FIG. 2 is a sectional view of a pulverized coal burner 19 related to the pulverized coal boiler system of FIG. 1, and FIG. 3 shows a wind box 12 of the pulverized coal burner 19. FIG. 3A is a perspective view (FIG. 3A) and a diagram showing a wind tunnel test result relating to the wind box 12 (FIG. 3B).
The fuel of the present invention is not limited to pulverized coal, and any type or composition may be used as long as it is a pulverized solid fuel that can be transported by airflow. Moreover, although it describes about the case where air is mainly used as fuel conveyance gas and combustion gas, it is not necessarily limited to only air, combustion exhaust gas, mixed gas of oxygen and combustion exhaust gas, etc. Any kind and composition may be used as long as they are used as a fuel conveying gas and a combustion gas in a combustion apparatus such as a boiler.

The pulverized coal boiler system shown in FIG. 1 constitutes the furnace wall 10 by supplying pulverized coal and combustion air to a burner 19 provided in a plurality of stages on the furnace wall 10 of the boiler furnace 18 to burn the pulverized coal. A heat exchanger such as a superheater (not shown) provided in the water tube wall and the furnace is heated to generate water vapor.

The pulverized coal supplied to the burner 19 is pulverized by pulverizing the coal in the bunker 20 with a mill 21, and the pulverized coal is air-flowed by the blower 23 and supplied to the burner 19. Combustion air supplied to the burner 19 and the after-air port 24 is supplied via a duct 16 by a blower 25, and combustion air is supplied to the pulverized coal burner 19 from a wind box 12 disposed outside the boiler furnace wall 10. Supplied.

An oil spray nozzle 7 is disposed on the central axis of the pulverized coal burner 19, and a fuel nozzle 3 through which a solid-gas two-phase flow 1 of pulverized coal and conveying air flows is disposed on the outer periphery thereof, and combustion air 2 is disposed on the outer periphery of the fuel nozzle 3. The secondary air nozzle 8 and the tertiary air nozzle 11 which eject are provided. As shown in FIG. 2, the outer peripheral wall of the tertiary air nozzle 11 is composed of a wind box 12.
The oil spray nozzle 7 is used for auxiliary combustion when the burner 19 is started or when low-load combustion is performed. A venturi 6 for narrowing the inner diameter of the fuel nozzle 3 is disposed on the inner peripheral wall of the fuel nozzle 3, and a pulverized coal concentrator 5 is provided on the outer periphery of the oil spray nozzle 7 near the outlet of the fuel nozzle 3. The flame holder 4 is provided at the tip of the partition wall (the outlet of the nozzles 3 and 8) separating the fuel nozzle 3 and the secondary air nozzle 8, and the tip of the partition wall (nozzle) separating the secondary air nozzle 8 and the tertiary air nozzle 11 is used. 8 and 11 outlets) are provided with guide sleeves 13 oriented in the direction of diffusing fluid from the central axis of the burner 19.

Thus, in this embodiment, each burner 19 is composed of the oil spray nozzle 7, the fuel nozzle 3, the secondary air nozzle 8, the tertiary air nozzle 11, and the wind box 12 constituting the outer peripheral wall of the tertiary air nozzle 11. The burner 19 is installed on the furnace wall 10 of the furnace 18.
Hereinafter, although demonstrated using drawing, this invention is not limited to those structures.

A perspective view of the wind box 12 of the pulverized coal burner 19 of this embodiment is shown in FIG. 3 (a), a cross-sectional view taken along the line AA in FIG. 2 (FIG. 4 (a)), and a cross-sectional view taken along the line BB in FIG. FIG. 4 shows (FIG. 4B). In addition, the black arrow shown in drawing after FIG. 4 shows the inflow direction of combustion air.

Further, FIG. 4 does not show the heavy oil nozzle 7 and the pulverized coal nozzle 3, and the heavy oil nozzle 7 and the pulverized coal nozzle 3 are installed in the cylindrical through hole of the wind box 12. The furnace wall of the through hole constitutes the outer wall of the secondary air nozzle 8.

As shown in FIG. 4, a wind box 12 provided with combustion air inlets 12 a and 12 b is arranged in a direction perpendicular to the central axis direction of the pulverized coal burner 19, and it seems as if the through hole provided in the window box 12 is provided. The secondary air nozzle 8 is arranged as inserted.

In addition, the wind box 12 is provided with two combustion air inlets 12a and 12b, and a partition plate 14 for partitioning the two combustion air inlets (combustion gas openings) 12a and 12b is provided. The outer wall of the secondary air nozzle 8 that constitutes the through hole of the wind box 12 is connected to the outside of a portion that bisects the window.

In the vicinity of the combustion air inlets 12 a and 12 b inside the wind box 12 divided into two vertically by the partition plate 14, there is a rotating shaft in a direction transverse to the flow of combustion air introduced into the wind box 12. The upper and

lower dampers

15a and 15b that change the area in which the combustion air flows are provided, and the rotational angles of the two

dampers

15a and 15b are adjusted separately, so that the momentum of the combustion air ejected from the pulverized coal burner 19 is increased. Deviations can be given up and down inside the windbox 12.

For example, by closing the upper damper 15a and opening the lower damper 15b, the amount of combustion air jetted below the burner 19 increases, and the momentum of the combustion air below the burner 19 increases. Thus, the flame in the boiler furnace 18 can be deflected downward.
The

dampers

15a and 15b are disposed inside the box 12 by a length L1 from the inlet opening of the wind box 12 in a state where the planes of the

dampers

15a and 15b are disposed in the direction along the flow of the combustion air. .

FIG. 3 shows the result of the velocity distribution of the tertiary air flow path outlet when the downward deflection of the flame was conducted in a test to give a deviation in the vertical momentum of the burner 19 of the tertiary air ejected from the tertiary air nozzle 11 into the furnace by the wind tunnel test. Shown in b). It was confirmed by this wind tunnel test that the momentum of the combustion air below the burner 19 was increased by adjusting the rotation angle of the upper and lower

rotary dampers

15a and 15b. When the flame is deflected in the furnace 18 on the upper side of the burner 19, the upper rotary damper 15a is opened, and the lower rotary damper 15b is closed.

Since the pulverized coal burner 19 is provided with the secondary air nozzle 8 having the guide sleeve 13 at the tip, the combustion air can be ejected stepwise. Two openings 8a are provided on the outer periphery of the secondary air nozzle 8 in the vertical direction, and a slide for adjusting the amount of air supplied from the opening 8a into the secondary air nozzle 8 as shown in FIG. It is desirable to provide an air amount adjusting mechanism such as a type damper 9a, 9b.

For example, when the amount of combustion air ejected from the lower side of the burner 19 is increased by closing the upper rotary damper 15a and opening the lower rotary damper 15b, the secondary air nozzle 8 is fully closed by a sliding damper 9a, thereby preventing air from flowing into the upper secondary air nozzle 8 and the tertiary air nozzle 11 and ejecting from the secondary air nozzle 8 into the furnace f18. The momentum of air can be kept substantially uniform in the circumferential direction, and flame holding properties can be maintained.

It should be noted that even if the upper opening 8a of the secondary air nozzle 8 is fully closed by the sliding damper 9a, the secondary air nozzle 8 does not have to enter the secondary air nozzle 8 as long as combustion air flows from somewhere. The momentum of the air ejected from the air nozzle 8 into the furnace 18 can be kept substantially uniform in the circumferential direction of the secondary air nozzle 8, but if the downward deflection of the flame in the furnace 18 is not desired. It is necessary to fully close the upper opening 8a of the secondary air nozzle 8 with the sliding damper 9a.

It is possible to deflect the direction of the flame in the furnace 18 only by giving a deviation to the momentum of the combustion air in the upper half and the lower half of the burner 19 while maintaining the flame holding property by adjusting the inflow amount of the combustion air. it can. The combustion air inlets 12a and 12b obtained by dividing the inside of the wind box 12 shown in FIG. 5 by the partition plate 14 are further divided into two, and the dampers 15aa and 15ab and the dampers 15ba and 15bb are respectively connected to the combustion air inlets 12a and 12b. In the same way, the direction of the flame in the furnace 18 can be deflected by giving a deviation to the momentum of the combustion air in the upper half and the lower half of the burner 19.

In this embodiment, as shown in FIG. 6, a burner 19 having the wind box 12 is installed on the furnace wall 10 of the boiler furnace 18, and combustion air is supplied to the burner 19 from a duct 16 provided outside the furnace wall 10. . However, the arrangement of the duct 16 depends on the boiler structure and the installation angle of the burner 19 on the furnace wall 10. Further, as shown in FIG. 7, even if the burners 19 having the wind box 12 are arranged inside the duct 16, the momentum of the combustion air in the upper half and the lower half of the burner 19 is given a deviation so that the inside of the furnace 18. The direction of the flame can be deflected.

In this embodiment, as shown in FIGS. 8 and 9, a wind box 12 into which combustion air flows only from above, which is perpendicular to the central axis direction of the burner 19, is provided. The partition plate 14 and the rotary damper 15 are provided, and by adjusting the damper 15, the momentum of the combustion air jetted into the furnace can be given a vertical deviation.

As shown in FIG. 8, in this embodiment, three windboxes 12 into which combustion air flows only from one direction of the upper combustion air inlets 12a, 12b perpendicular to the central axis direction of the burner 19 are provided. A partition plate 14 is provided so as to be divided. Further,

dampers

15a, 15b, 15b of air amount regulators are provided on the upstream side of the three divided air inflow paths of the wind box 12, respectively. Therefore, air flows into the upper side of the burner 19 from the center of the wind box 12, and air flows into the lower side of the burner 19 from the left and right sides of the wind box 12.

In the embodiment shown in FIG. 9, the wind box 12 into which combustion air flows only from one direction of the upper combustion air inlets 12a and 12b perpendicular to the central axis direction of the burner 19 is divided into four. Two partition plates 14 are provided. Further, the combustion air inlet 12a at the center of the wind box 12 is divided into two, and dampers 15b, 15aa, 15ab, 15b of air amount regulators are provided on the upstream side of the respective air inflow passages. Also in the case shown in FIG. 9, air flows into the upper side of the burner 19 from the upper center portion of the wind box 12, and air flows into the lower side of the burner 19 from the left and right sides of the wind box 12.

In the window box 12 shown in FIGS. 8 and 9, for example, the damper 15a or dampers 15aa and 15ab near the combustion air inlet 12a in the center is closed, and other parts near the left and right

combustion air inlets

12b and 12b are closed. By opening the two

dampers

15b and 15b, the amount of combustion air jetted below the burner 19 is increased, and the momentum of the combustion air flow to the lower side of the burner 19 is increased, so that the flame in the furnace 18 is increased. Can be changed downward. FIG. 3 shows the result of a test for giving a deviation to the momentum of the upper and lower of the burner 19 of the tertiary air in the wind tunnel test.

It can be confirmed that the momentum of the lower side of the burner 19 in the furnace 18 can be increased by adjusting the amount of fuel air flowing into the wind box 12 by the three or four dampers 15 in this way. The case where the flame is deflected to the upper side of the burner 19 in the furnace can be dealt with by performing the reverse operation of the above operation.

The secondary air nozzle 8 having a guide sleeve 13 at the tip is provided in the wind box 12 so that combustion air can be ejected stepwise. An opening 8a is provided in the outer wall of the secondary air nozzle 8, and an air amount adjusting mechanism such as slide type dampers 9a and 9b shown in FIG. 2 that can adjust the air amount to the secondary air nozzle 8 is used. It is desirable to adjust the opening degree of the opening 8a. For example, the damper 15a near the combustion air inlet 12a in the center shown in FIG. 8 is closed, and the two

dampers

15b and 15b near the left and right

combustion air inlets

12b and 12b are opened, so that the inside of the furnace 18 When the amount of combustion air jetted below increases, the opening 8a of the secondary air nozzle 8 above the wind box 12 is fully closed by the sliding dampers 9a and 9b, so that 3 above the burner 19 The inflow to the secondary air nozzle 11 can be prevented, and the momentum of the air ejected from the secondary air nozzle 8 into the furnace 18 can be kept substantially uniform in the circumferential direction, so that the flame holding property can be maintained.

It is possible to deflect the flame only by giving a deviation to the momentum of the upper and lower of the burner 19 of the tertiary air while maintaining the flame holding property by the above operation. As shown in FIG. 9, these structures and operation methods have the same effect by the damper adjustment method even when the combustion air inlet 12a at the center of the wind box 12 is divided into two and dampers 15aa and 15ab are provided nearby. Obtainable.

In this embodiment, as shown in FIG. 10, a burner 19 having the wind box 12 is installed outside the furnace wall 10 of the boiler furnace 18, and combustion air is introduced into the duct 16 connected to the wind box 12 from the inflow direction shown in the figure. It is a structure to insert. However, the arrangement of the duct 16 depends on the boiler structure and the installation angle of the burner 19 on the furnace wall 10. Also, as shown in FIG. 11, the same operation method can be executed even if the burners 19 having the window boxes 12 are respectively arranged inside the duct 16.

The present embodiment shown in FIGS. 12 and 13 is provided with a wind box 12 into which combustion air flows only from the combustion air inlets 12a and 12b below in the direction perpendicular to the central axis of the burner 19. 12 is partitioned by a plurality of partition plates 14, and

dampers

15b, 15a, 15b; 15b, 15aa, 15ab, 15b are provided in the combustion air nozzles of the wind box 12 partitioned by the partition plates 14, respectively. , 15 a, 15 b; 15 b, 15 aa, 15 ab, 15 b is adjusted to open and close the burner 19 with a deviation in the momentum of the combustion air ejected from the burner 19 toward the furnace 18.

In this embodiment shown in FIG. 12,

partition plates

14 and 14 are provided so as to divide the wind box 12 into which combustion air flows only from one direction perpendicular to the central axis direction of the burner 19 into three. It has a structure. Further,

dampers

15b, 15a, 15b of air amount regulators are provided upstream of the three divided

air inlet passages

12b, 12a, 12b of the wind box 12, respectively. Therefore, the air from the combustion air inlet 12a in the center of the wind box 12 flows into the lower side of the burner 19, and the air flows into the upper side of the burner 19 from the left and right

combustion air inlets

12b and 12b of the wind box 12. To do.

Thus, for example, the damper 15a near the combustion air inlet 12a at the center of the wind box 12 is opened, and the

dampers

15b and 15b near the left and right

combustion air inlets

12b and 12b are closed. The amount of combustion of the combustion air on the lower side increases and the momentum of the combustion air on the lower side of the burner 19 increases, so that the flame in the furnace 18 can be changed downward. FIG. 3 shows the results of testing by giving deviations in the momentum up and down of the tertiary air in the wind tunnel test.

It can be confirmed that the momentum on the lower side of the burner 19 can be increased by adjusting the degree of opening and closing of the three

dampers

15b, 15a, 15b, and when the flame is deflected to the upper side of the burner 19 in the furnace 18, the above operation is reversed. This can be done by performing an action.

A secondary air nozzle 8 having a guide sleeve 13 is provided in the wind box 12 so that combustion air is ejected in a direction of expanding from the outlet of the burner 19. Also, the secondary air nozzle 8 is provided with an opening 8a (FIG. 2), and it is desirable to provide a sliding damper 9 shown in FIG. 2 to adjust the amount of air flowing in from the opening 8a. For example, the damper 15a near the combustion air inlet 12a at the center of the windbox 12 is closed, and the

dampers

15b and 15b near the left and right

combustion air inlets

12b and 12b are opened, so that the When the amount of combustion air jetted increases, the opening 8a of the secondary air nozzle 8 on the lower side of the wind box 12 is fully closed by the sliding damper 9, so that the tertiary on the lower side of the burner 19 is closed. The inflow of air into the air nozzle 11 can be prevented, and the momentum of the air ejected from the secondary air nozzle 8 into the furnace 18 can be kept substantially uniform in the circumferential direction, so that the flame holding ability can be maintained. The flame can be deflected only by adjusting the amount of tertiary air ejection and giving a deviation to the momentum of the air above and below the burner 19 while maintaining the flame holding property by the above operation. As shown in FIG. 13, these structures and operating methods are provided with

combustion air inlets

12b and 12b on both lower sides of the wind box 12, and the central combustion air inlet 12a is divided into two parts. The present invention can also be applied to the case where dampers 15b, 15aa, 15ab, 15b are provided on the upstream side, and the same effect can be obtained by adjusting the dampers 15b, 15aa, 15ab, 15b.

In this embodiment, as shown in FIG. 14, a burner 19 having the window box 12 is installed on the boiler furnace wall 10, and combustion air is supplied to the burner 19 from a duct 16 provided outside the furnace wall 10. Features. However, the arrangement of the duct 16 depends on the boiler structure and the installation angle of the burner 19. Also, as shown in FIG. 15, the same operation method can be performed even if the burners 19 having the wind box 12 are respectively arranged inside the duct 16.

According to the third embodiment, since the maximum heat load area of the furnace 18 is shifted downward by deflecting the flame in the furnace 18 downward, the heat absorption of the furnace is increased and the exhaust gas temperature at the outlet of the furnace 18 is reduced. Further, the combustion zone of the burner 19 is shifted downward, and the residence time of the NOx reduction zone in the furnace 18 between the burner 19 and the after-air port 24 is formed evenly in the vertical direction of the burner 19. The pulverized coal burner 19 which can extend the case and reduce the NOx concentration can be provided.

In this embodiment, in addition to the configurations of the first to third embodiments, the supply air amount regulator for the individual burner 19 is used to adjust the flow rate of the combustion air flowing into each burner 19 upstream of the damper 15. In this configuration, a second damper 17 is provided.
Since the fuel supplied to the burners 19 arranged on the boiler furnace wall 10 may be distributed, the combustion air for each burner 19 so that the combustion air flow rate matches the fuel supply amount. It is desirable that the flow rate can be adjusted.
Here, even with only the first damper 15, if the opening degree is adjusted for each burner 19, the combustion air flow rate can be adjusted, but originally, there is a deviation in the momentum of the combustion air above and below the burner 19. If the first damper 15 provided for the purpose of giving is provided with a function of adjusting the combustion air flow rate corresponding to the fuel supply amount, the control becomes difficult.
Therefore, in the present embodiment, the first damper 15 and the second damper 17 that share the two different functions are provided independently.
FIGS. 16 and 17 show, in addition to the

first dampers

15a and 15b that give deviation to the upper and lower air momentum of the burner 19 described in the first embodiment (FIGS. 4 and 5), on the upstream side of the

first dampers

15a and 15b. The structure which provided the 2nd dampers 17a and 17b for adjusting the flow volume of the combustion air which flows in into the burner 19 is shown.
As described above, for example, the upper first damper 15a in the

first dampers

15a and 15b that gives a deviation to the upper and lower combustion air momentum of the burner 19 is closed and the lower first damper 15b is opened. When the amount of combustion air jetted below the burner 19 increases and the momentum of the combustion air below the burner 19 increases, the flame in the furnace 18 is deflected downward (see FIG. 3B). ).
By providing the second dampers 17a and 17b upstream of the

first dampers

15a and 15b, the flow rate of the combustion air flowing into each burner 19 can be reduced without suppressing the deviation in the momentum of the combustion air above and below the burner 19. Can be adjusted individually.
It is sufficient that

first dampers

15a and 15b as regulators for giving deviations to the combustion air momentum above and below each burner 19 in the individual windbox 12 are provided on the downstream side of the second dampers 17a and 17b. It does not matter where the second dampers 17a, 17b are arranged.
In addition, instead of the illustrated butterfly type damper, the

first dampers

15a and 15b and the second dampers 17a and 17b may be configured to adjust a hole area by sliding a plurality of stacked perforated plates. Any structure can be used as long as it has a function of adjusting the gas flow rate.

In the present embodiment, a secondary air nozzle 8 having a guide sleeve 13 as shown in FIG. 2 is provided in the wind box 12, and the combustion air is ejected while expanding from the outlet of the burner 19 toward the furnace 18. It has a structure to do. The secondary air nozzle 8 is provided with an opening 8a, and it is desirable to provide a slide type damper 9 capable of adjusting the amount of air to the secondary air nozzle 8.
For example, when the upper first damper 15a in the window box 12 shown in FIG. 16 is closed and the lower first damper 15b is opened, the amount of combustion air jetted below the burner 19 increases. The opening 8a of the secondary air nozzle 8 in the upper part of the wind box 12 is fully closed by the sliding damper 9a, so that the combustion air flows into the tertiary air nozzle 11 in the upper part of the window box 12. The momentum of the combustion air ejected from the secondary air nozzle 8 into the furnace 18 can be kept substantially uniform in the circumferential direction of the burner 19, and flame holding performance can be maintained.
By operating the

first dampers

15a and 15b and the sliding damper 9a, the flame in the furnace 18 can be reduced only by giving a deviation in the momentum of the tertiary air above and below the burner 19 while maintaining the flame holding performance of the burner 19. Can be deflected.

As shown in FIG. 17, these structures and operation methods are such that the combustion air inlets 12a and 12b in the wind box 12 are divided into two parts, and the first dampers 15aa and 15ab; With the damper adjustment method provided with 15bb and the second dampers 17aa, 17ab; 17ba, 17bb, the flow rate of the combustion air flowing into each burner 19 is individually controlled without suppressing the deviation of the momentum of the combustion air above and below the burner 19 Can be adjusted.

Also in this embodiment, as shown in FIG. 18, the burners 19 having the wind box 12 are respectively arranged inside the duct 16. A plurality of burners 19 arranged in a row in the horizontal direction of the furnace wall 10 are divided into the second dampers 17 (17a, 17b and 17aa, 17ab; 17ba, 17bb) shown in FIGS. It can adjust by providing in.
Further, as shown in FIG. 19, a burner 19 having the window box 12 shown in FIGS. 16 and 17 is installed outside the furnace wall 10 of the boiler, and combustion air from the outside of the furnace 18 passes through the duct 16. Alternatively, a configuration may be adopted in which the gas is supplied to the burner 19 having each window box 12.

The present invention further increases the industrial applicability by adding a flame deflection and heat absorption control function and a combustion gas flow rate adjustment function of the individual burner 19.

DESCRIPTION OF SYMBOLS 1 Solid-gas two-phase flow 2 Combustion air 3 Fuel nozzle 4 Flame holder 5 Pulverized coal concentrator 6 Venturi 7 Heavy oil nozzle 8 Secondary air nozzle 9 Sliding damper 10 Boiler furnace wall 11 Tertiary air nozzle 12 Wind box 13 Guide Sleeve 14 Partition plate 15 (15a, 15aa, 15ab, 15b, 15ba, 15bb) Damper (first flow rate adjusting means)
16 Duct
17 (17a, 17aa, 17ab, 17b, 17ba, 17bb) Damper (second flow rate adjusting means)
18 Boiler Furnace 19 Burner 20 Bunker 21 Mill 23 Blower 24 After Airport 25 Blower

Claims

A cylindrical fuel nozzle for injecting a mixture of fuel and its carrier gas into the furnace, one or more cylindrical combustion gas nozzles for injecting a combustion gas provided on the outer periphery of the fuel nozzle into the furnace, and A combustion apparatus in which a plurality of burners each having a wind box for supplying combustion gas to a combustion gas nozzle are arranged side by side on the furnace wall of the furnace,
The wind box has a combustion gas inflow opening through which combustion gas flows from one direction oriented in a direction perpendicular to the axial direction of the burner, and the combustion gas flows from the combustion gas inflow opening. Are divided so as to form a plurality of parallel flow paths into which the gas flows in parallel. Among the plurality of flow paths, some of the flow paths are above the combustion gas nozzle and the remaining flow paths are the combustion gas. A combustion apparatus connected to a lower side of a nozzle, wherein the plurality of flow paths are provided with first flow rate adjusting means for independently adjusting the flow rate of the combustion gas.
The combustion apparatus according to claim 1, wherein one duct for supplying combustion gas to the plurality of wind boxes from the outside of the furnace is installed outside a furnace wall in which the wind box is installed.
The combustion apparatus according to claim 1 or 2, wherein a plurality of the wind boxes are installed side by side inside or outside the one duct.
The second flow rate adjusting means for adjusting the flow rate of the combustion gas flowing into each burner is provided in each window box upstream of the first flow rate adjusting means. 4. The combustion apparatus according to any one of 3.