WO2018150701A1 - Combustion burner and boiler with same - Google Patents

Abstract

Provided is a combustion burner comprising: a fuel nozzle (110) forming a fuel gas flow passage (111) for supplying a fuel gas to a furnace; secondary air nozzles (120) forming secondary air flow passages (121) for supplying secondary air to the furnace from the outside of the fuel nozzle (110); and a pair of secondary air supply ports arranged above and below the secondary air nozzles (120) and supplying secondary air to the furnace (11). The fuel gas flow passage (111) and the secondary air flow passages (121) are flow passages having a rectangular shape in a cross-section taken perpendicular to an axis. The sum of the flow passage widths of the openings, open to the furnace, of secondary air flow passages (121) located to the left and right of the fuel gas flow passage (111) is greater than the sum of the flow passage widths of the openings, open to the furnace, of secondary air flow passages (121) located above and below the fuel gas flow passage (111).

Description

Combustion burner and boiler provided with the same

The present disclosure relates to a combustion burner applied to a boiler for generating steam for power generation or factory use, and a boiler including the same.

Conventionally, a solid fuel burning burner is known which includes a fuel burner for charging pulverized coal and primary air into the furnace, and a secondary port for fuel burner for injecting secondary air from the outer periphery of the fuel burner (for example, a patent) Reference 1). The solid fuel fired burner of Patent Document 1 includes a pair of secondary air inlet ports disposed above and below the secondary port for the fuel burner.

In the solid fuel fired burner of Patent Document 1, secondary air is supplied from above and below of the fuel burner secondary port. Therefore, the upper and lower portions of the flame formed by the fuel burner are regions where the amount of air for fuel is relatively large.
On the other hand, the solid fuel fired burner of Patent Document 1 does not have a secondary air inlet port on the left and right of the secondary port for fuel burner. Therefore, the right and left sides of the flame formed by the fuel burner become regions where the amount of air for fuel is relatively small.

JP, 2015-200500, A

In the solid fuel fired burner of Patent Document 1, when the flame formed by the fuel burner becomes a region of a reducing atmosphere with a relatively small amount of air to fuel, corrosion tends to occur on the adjacent furnace wall. There is a problem of This is because the sulfur content (S content) in the pulverized coal is converted to hydrogen sulfide (H ₂ S) and contacts the furnace wall in the area of reducing atmosphere.

Moreover, the boiler provided with the solid fuel burning burner of Patent Document 1 adopts a swirling combustion system in which the solid fuel burning burner is disposed at four corner portions. Therefore, the flame of the solid fuel fired burner on the upstream side in the swirling direction may interfere with the flame of the solid fuel fired burner on the downstream side, thereby inhibiting the combustion and deteriorating the combustion characteristics.

The present disclosure solves the above-mentioned problems, and provides a combustion burner capable of suppressing corrosion of a furnace wall due to generation of hydrogen sulfide and interference by flames of other adjacent combustion burners, and a boiler including the same. The purpose is

In order to achieve the above object, a combustion burner of the present disclosure includes a fuel gas flow that extends in a tubular shape along an axis and supplies a fuel gas obtained by mixing a fuel obtained by grinding a carbon-containing solid fuel and primary air to a furnace. A fuel nozzle forming a passage, a secondary air nozzle forming a secondary air flow path extending cylindrically along the axis and supplying secondary air to the furnace from the outside of the fuel nozzle, the secondary And a pair of secondary air supply ports disposed above and below the air nozzle and supplying secondary air to the furnace, wherein the fuel gas passage and the secondary air passage are orthogonal to the axis. The cross-section is a flow passage having a rectangular shape, and the sum of the flow passage widths of the openings to the furnace of the secondary air flow passage located on the right and left of the fuel gas flow passage is the fuel gas flow passage. Said secondary sky located above and below Greater than the sum of the channel width of the opening into the furnace of the channel.

According to the above configuration, the flow rate of the secondary air supplied to the furnace from the right and left of the fuel gas flow path where the secondary air inlet port is not disposed is increased, and the right or left furnace of the combustion burner is Hydrogen sulfide (H ₂ S) produced in the area adjacent to the wall is reduced. This suppresses the corrosion of the furnace wall due to the generation of hydrogen sulfide.

According to the present disclosure, it is possible to provide a combustion burner capable of suppressing the corrosion of the furnace wall due to the generation of hydrogen sulfide and the interference by the flame of another adjacent combustion burner, and a boiler provided with the same.

It is a schematic block diagram showing the pulverized coal burning boiler to which the combustion burner of one embodiment of this indication was applied. It is a top view showing the combustion burner in the pulverized coal burning boiler shown in FIG. It is a partial longitudinal cross-sectional view of the combustion burner shown in FIG. It is the front view which saw the combustion burner shown in FIG. 2 from the furnace. It is a front view which shows the flow-path width | variety of the opening part of the secondary air flow path of the combustion burner shown in FIG. It is a front view which shows the flow-path width | variety of the opening part of the secondary air flow path of the combustion burner of a comparative example. It is a fragmentary longitudinal cross-sectional view of the combustion burner of other embodiment. It is the front view which saw the combustion burner shown in FIG. 7 from the furnace.

Hereinafter, preferred embodiments of the combustion burner of the present disclosure will be described in detail with reference to the accompanying drawings. Note that the present disclosure is not limited by the embodiments, and in the case where there are a plurality of embodiments, the present disclosure also includes those configured by combining the respective embodiments.

A pulverized coal burning boiler to which a combustion burner according to some embodiments of the present disclosure is applied uses pulverized coal obtained by pulverizing coal as a carbon-containing solid fuel, burns the pulverized coal by the combustion burner, and is generated by this combustion It is a boiler capable of recovering heat.

As shown in FIG. 1, the pulverized coal burning boiler 10 of the present embodiment is a conventional boiler, and has a furnace 11, a combustion apparatus 12 and a flue 13. The furnace 11 has a hollow shape of a square cylinder and is installed along the vertical direction, and the combustion apparatus 12 is provided at the lower part of the furnace wall constituting the furnace 11.

The combustion device 12 has a plurality of combustion burners 100A, 100B, 100C, 100D, 100E mounted on the furnace wall. In the present embodiment, the combustion burners 100A, 100B, 100C, 100D, 100E are provided as a set of four arranged along the circumferential direction centering on the vertical direction in which the furnace 11 extends. , 5 sets (5 stages) are arranged along the vertical direction. Although five sets are used here, six sets or any other number of sets can be used.

And each combustion burner 100A, 100B, 100C, 100D, 100E is a pulverized coal machine (mill; pulverizer) 31, 32, 33, 34, 35 via pulverized coal supply pipes 26, 27, 28, 29, 30. Is linked to The pulverized coal machine 31, 32, 33, 34, 35 is not shown, but the pulverizing table is rotatably supported within the housing with a rotational axis along the vertical direction, and is opposed to the upper side of the pulverizing table A plurality of grinding rollers are rotatably supported in association with the rotation of the grinding table. Therefore, when coal is introduced between the plurality of grinding rollers and the grinding table, the pulverized coal which has been pulverized to a predetermined size and classified by the transport air (primary air) is pulverized by the pulverized coal supply pipe 26, The combustion burners 100A, 100B, 100C, 100D, and 100E are supplied from 27, 28, 29, and 30, respectively.

In the furnace 11, a wind box 36 is provided at the mounting position of each of the combustion burners 100A, 100B, 100C, 100D and 100E, and one end of an air duct (secondary air supply pipe) 37 is attached to the wind box 36. A blower 38 is attached to the other end of the air duct 37. Further, the furnace 11 is provided with an additional air nozzle 39 vertically above the mounting position of each of the combustion burners 100A, 100B, 100C, 100D, 100E. The additional air nozzle 39 is connected to an end of a branched air duct 40 branched from the air duct 37. Therefore, the combustion air (secondary air) sent by the blower 38 is supplied from the air duct 37 to the air box 36 and is supplied from the air box 36 to the combustion burners 100A, 100B, 100C, 100D, 100E. And the combustion air (additional air) sent by the blower 38 can be supplied from the branch air duct 40 to the additional air nozzle 39.

Therefore, in the combustion apparatus 12, each combustion burner 100 A, 100 B, 100 C, 100 D, 100 E mixes the pulverized fuel mixture (fuel gas) in which the pulverized coal and the transport air (primary air) are mixed into the furnace 11. As well as being capable of being blown, combustion air can be blown into the furnace 11. The combustion apparatus 12 can form a flame by igniting the pulverized fuel mixture with an ignition torch (not shown).

In the furnace 11, a flue 13 is connected to the upper part in the vertical direction, and to this flue 13, a superheater (super heater) 41, which is a heat exchanger for recovering heat of combustion gas as a convection heat transfer portion, 42, reheaters 43, 44 and economizers 45, 46, 47 are provided, and heat exchange is performed between the combustion gas generated by the combustion in the furnace 11 and water or steam.

The flue 13 is connected to an exhaust gas pipe 48 through which the combustion gas subjected to heat exchange is discharged as exhaust gas downstream of the gas flow. The exhaust gas pipe 48 is provided with an air heater 49 between it and the air duct 37, and performs heat exchange between the air flowing through the air duct 37 and the exhaust gas flowing through the exhaust gas pipe 48, and the combustion burners 100A, 100B, 100C, The temperature of combustion air supplied to 100D and 100E can be raised. Although not shown, the exhaust gas pipe 48 is provided with a NOx removal device, an electrostatic precipitator, an induction fan, a desulfurization device, and a chimney at the downstream end.

Therefore, when the pulverized coal machine 31, 32, 33, 34, 35 is driven, the pulverized coal produced together with the transfer air (primary air) is supplied with pulverized coal supply pipes (fuel supply pipes) 26, 27, 28, 29, The combustion burners 100A, 100B, 100C, 100D and 100E are supplied through 30. Further, the heated combustion air (secondary air) is supplied from the air duct 37 to the combustion burners 100A, 100B, 100C, 100D, 100E through the air box 36, and from the branch air duct 40 to the additional air nozzle Supplied to 39 The temperature of the transport air (primary air) is low so that the pulverized coal does not ignite, and the combustion air (secondary air) is heated by the air heater 49, so the temperature is higher than the primary air and the pulverized fuel mixture .

Then, the combustion burners 100A, 100B, 100C, 100D, 100E blow the pulverized fuel mixture (fuel gas) in which the pulverized coal and the conveying air are mixed into the furnace 11 and also blows the combustion air into the furnace 11, The flame can be formed by ignition. In addition, the additional air nozzle 39 can perform combustion control to blow additional air into the furnace 11 and optimize the amount of air to the pulverized coal. In the furnace 11, the pulverized fuel mixture and the combustion air are burned to generate a flame, and when the flame is generated in the region in the lower portion in the vertical direction in the furnace 11, the combustion gas (exhaust gas) rises in the furnace 11 And is discharged to the flue 13.

That is, the combustion burners 100A, 100B, 100C, 100D, and 100E blow the pulverized coal mixture and the combustion air (secondary air) into the combustion area of the furnace 11, and ignite at this time to generate a flame swirling flow in the combustion area. Is formed. Then, the flame swirling flow rises while swirling and reaches the reduction region. The additional air nozzle 39 blows additional air vertically above the reduction region in the furnace 11. In the furnace 11, the inside is maintained in a reducing atmosphere by setting the amount of supplied air to be less than the theoretical amount of air with respect to the supplied amount of pulverized coal. Then, NOx generated by the combustion of the pulverized coal is reduced by the furnace 11, and after that, additional air (additional air) is supplied to complete the oxidation combustion of the pulverized coal, and the amount of NOx generated by the combustion of the pulverized coal is Reduced.

At this time, the water supplied from the water supply pump (not shown) is preheated by the economizer 45, 46, 47 and then supplied to the steam drum (not shown) and supplied to each water pipe (not shown) of the furnace wall. While being heated, it is heated to become saturated steam and fed to the steam drum. Furthermore, the saturated steam of the steam drum is introduced into the superheaters 41 and 42 and is overheated by the combustion gas. The superheated steam generated by the superheaters 41 and 42 is supplied to a turbine (not shown) of the power plant. Further, the steam taken out in the middle of the expansion process of the steam supplied by the turbine is introduced into the reheaters 43 and 44, and is again overheated, returned to the turbine and expanded, and the turbine is rotationally driven. In addition, although the furnace 11 was demonstrated as a drum type (steam drum), it is not limited to this structure.

After that, the exhaust gas that has passed through the economizers 45, 46, 47 of the flue 13 is removed by the exhaust gas pipe 48 with a denitration device (not shown) by the supplied ammonia and catalyst to remove harmful substances such as NOx. After the particulate matter is removed by the electrostatic precipitator and the sulfur content is removed by the desulfurization apparatus, it is discharged to the atmosphere from the chimney.

Here, although the combustion apparatus 12 will be described in detail, the combustion burners 100A, 100B, 100C, 100D, and 100E constituting the combustion apparatus 12 are positioned at the uppermost stage because they have substantially the same configuration. Only the combustion burner 100A will be described.

The combustion burner 100A is comprised from combustion burner 100Aa, 100Ab, 100Ac, 100Ad provided in the four wall surfaces which form the furnace 11, as shown in FIG. The combustion burners 100Aa, 100Ab, 100Ac, 100Ad are connected to the branch pipes 26a, 26b, 26c, 26d branched from the pulverized coal supply pipe 26, and the branch pipes 37a, 37b, 37c branched from the air duct 37. , 37d are linked.

Therefore, the combustion burners 100Aa, 100Ab, 100Ac, 100Ad on the respective wall surfaces of the furnace 11 center the furnace 11 on the pulverized fuel mixture in which the pulverized coal and the transfer air (primary air) are mixed. At the same time, a slight declination is provided, and at the same time, combustion air (secondary air) is blown to the outside of the pulverized fuel mixture. And, by igniting the pulverized fuel mixture from the combustion burners 100Aa, 100Ab, 100Ac, 100Ad, four flames F1, F2, F3, F4 can be formed, and the flames F1, F2, F3, F4 can be formed. Is a flame swirling flow that turns counterclockwise as viewed from above the furnace 11 (in FIG. 2). Here, although it shall counterclockwise rotate, each combustion burner 100Aa, 100Ab, 100Ac, 100Ad may be arrange | positioned so that it may become a flame swirling flow which turns clockwise.

Next, the combustion burner 100A will be described in detail.
As shown in the partial longitudinal sectional view of FIG. 3 and the front view of FIG. 4, the combustion burner 100A of this embodiment includes a fuel nozzle 110, a secondary air nozzle 120, and a pair of secondary air supply ports 130A and 130B. And. The longitudinal sectional view of FIG. 3 is a cross-sectional view of the combustion burner 100A shown in FIG.

The fuel nozzle 110 is a member formed to extend in a tubular shape along the axis X1. The fuel nozzle 110 forms a fuel gas channel 111 for supplying the pulverized fuel mixture supplied from the pulverized coal supply pipe 26 to the furnace 11 therein. The fuel gas flow channel 111 is a flow channel having a rectangular cross section orthogonal to the axis X1.

The shape of the opening at which the fuel nozzle 110 faces the furnace 11 is a shape extending straight in the same direction as the gas flow direction of the pulverized fuel mixture. As shown in FIG. 3, the height in the vertical direction of the fuel nozzle 110 is constant at H1. This is to prevent the pulverized coal contained in the pulverized fuel mixture from being led to the outer peripheral side with respect to the central axis (axis line X1) of the fuel gas passage 111.

The secondary air nozzle 120 is a member which is formed so as to extend in a cylindrical shape along the axis X 1 and is disposed so as to surround the outside with respect to the axis X 1 of the fuel nozzle 110. The secondary air nozzle 120 forms an annular secondary air flow passage 121 for supplying secondary air to the furnace 11 between the inner peripheral surface thereof and the outer peripheral surface of the fuel nozzle 110. The secondary air passage 121 has a rectangular cross section orthogonal to the axis X1.

The secondary air nozzle 120 supplies the secondary air supplied from the air box 36 to the furnace 11 via the secondary air passage 121. The height in the vertical direction of the secondary air nozzle 120 is fixed to H2 on the base end side, and is lowered from H2 to H3 on the tip end side.

The secondary air supply port 130 </ b> A is disposed above the secondary air nozzle 120 in the vertical direction, and supplies secondary air to the furnace 11. The secondary air supply port 130 B is disposed below the secondary air nozzle 120 in the vertical direction, and supplies secondary air to the furnace 11. The secondary air supply ports 130A and 130B supply the furnace 11 with the secondary air supplied from the air box 36. The heights of the secondary air supply ports 130A and 130B are fixed at H4 on the base end side and are lowered from H4 to H5 at the front end side.

Next, the flow passage width of the opening of the secondary air flow passage 121 to the furnace 11 will be described. FIG. 5 is a front view showing the flow passage width of the opening to the furnace 11 of the secondary air flow passage 121 of the combustion burner 100A shown in FIG. Here, W 1 is the horizontal width of the opening of the fuel nozzle 110, and W 2 is the horizontal width of the opening of the secondary air nozzle 120.

Here, the channel width of the opening to the furnace 11 of the secondary air channel 121 located to the right of the fuel gas channel 111 is Wr, and the secondary air stream located to the left of the fuel gas channel 111 The channel width of the opening to the furnace 11 of the channel 121 is W1. In addition, the channel width of the opening to the furnace 11 of the secondary air channel 121 located above the fuel gas channel 111 is taken as Hu, and the secondary air channel 121 located below the fuel gas channel 111 is Hu. The channel width of the opening to the furnace 11 is Hd.

Then, in the present embodiment, the fuel gas channel 111 and the secondary air channel 121 are formed so that the following conditional expression (1) holds between Wr, Wl, Hu, and Hd.
Hu + Hd <Wr + Wl (1)
In this condition, the sum of the channel widths of the openings to the furnace 11 of the secondary air channel 121 located on the right and left of the fuel gas channel 111 is located above and below the fuel gas channel 111. It is the condition that it is larger than the sum total of the channel width of the opening to furnace 11 of secondary air channel 121 which carries out. By satisfying the conditional expression (1), the flow rate of the secondary air supplied to the furnace from the right side and the left side of the fuel gas flow path 111 where the secondary air supply ports 130A and 130B are not disposed is increased.

Here, the fuel gas channel 111 and the secondary air channel 121 may be formed such that Wr and Wl have the same channel width. The flow channel width Wr of the secondary air flow channel 121 located on the right of the fuel gas flow channel 111 and the flow channel width Wl of the secondary air flow channel 121 located on the left of the fuel gas flow channel 111 are made to coincide with each other. Thus, the corrosion of the furnace wall due to the generation of hydrogen sulfide in the area adjacent to the furnace wall and the interference by the flame of the other adjacent combustion burner can be appropriately suppressed.

Further, the fuel gas channel 111 and the secondary air channel 121 may be formed such that Wr and Wl have different channel widths. As shown in FIG. 2, in the combustion burner 100A of the present embodiment, when the combustion burner 100A is viewed from the furnace 11, the furnace wall is disposed on the left of the fuel gas passage 111, and from the right of the fuel gas passage 111 Interference from the flame of the other combustion burner 100A on the upstream side of the swirling flow is received.

Therefore, if the influence of the corrosion of the furnace wall due to the generation of hydrogen sulfide is greater than the interference of the flame, it is desirable to make Wl wider than Wr. By increasing the secondary air supplied from the secondary air flow passage 121 located to the left of the fuel gas flow passage 111, it is possible to suppress the corrosion of the furnace wall due to the generation of hydrogen sulfide.

Also, if the influence of the flame interference is greater than the corrosion of the furnace wall due to the generation of hydrogen sulfide, it is desirable to make Wr wider than Wl. By increasing secondary air supplied from the secondary air flow passage 121 located to the right of the fuel gas flow passage 111, it is possible to suppress the interference by the flame of the other combustion burner 100A on the upstream side of the swirling flow. it can.

Further, in the present embodiment, it is desirable to form the fuel gas channel 111 and the secondary air channel 121 so that the following conditional expression (2) is satisfied.
1.5 ≦ (Wr + Wl) / (Hu + Hd) ≦ 6 (2)
Under these conditions, the channel width of the opening to the furnace 11 of the secondary air channel 121 located to the right and left of the fuel gas channel 111 is located above and below the fuel gas channel 111 2 The condition is that it is 1.5 times or more and 6 times or less the channel width of the opening of the next air channel 121 to the furnace 11. By satisfying conditional expression (2), the channel width of the opening of the secondary air channel 121 located on the right and left of the fuel gas channel 111 is set to the upper and lower sides of the fuel gas channel 111. It can be made sufficiently larger than the flow passage width of the opening of the secondary air flow passage 121 located at

Here, the combustion burner of the comparative example will be described. FIG. 6 is a front view showing the channel width of the opening of the secondary air channel of the combustion burner of the comparative example.
The shape of the fuel nozzle 110 is the same in both the combustion burner 100A of the present embodiment and the combustion burner of the comparative example. The shape of the opening where the fuel nozzle 110 faces the furnace 11 is a rectangular shape having a width W1 and a height H1.

In the combustion burner 100A of the present embodiment and the combustion burner of the comparative example, the shape of the secondary air nozzle 120 is different. The heights of the openings of the secondary air nozzle 120 of the present embodiment and the opening of the secondary air nozzle 120a of the comparative example are the same at H3. On the other hand, the width W3 of the secondary air nozzle 120a of the comparative example is narrower than the width W2 of the secondary air nozzle 120 of the present embodiment. In the comparative example, the passage width Wra of the opening to the furnace 11 of the secondary air passage 121 a located on the right of the fuel gas passage 111 and the secondary air flow located on the left of the fuel gas passage 111 The sum of the passage width Wla of the opening to the furnace 11 of the passage 121a and the passage width Hu of the opening to the furnace 11 of the secondary air passage 121 located above the fuel gas passage 111 and the fuel gas flow The sum of the flow passage widths Hd of the openings to the furnace 11 of the secondary air flow passage 121 located below the passage 111 is equal.

Thus, the sum (Wr + Wl) of the channel widths of the openings to the furnace 11 of the secondary air channel 121 located on the right and left of the fuel gas channel 111 of the present embodiment is the fuel of the comparative example. It is larger than the total (Wra + Wla) of the flow passage width of the opening to the furnace 11 of the secondary air flow passage 121a located on the right and left of the gas flow passage 111.

Here, assuming that the total area of the opening for blowing the secondary air blown by the blower 38 to the furnace 11 is S, the fuel gas passage 111 and the fuel gas passage 111 of the present embodiment so that the following conditional expression (3) holds. It is desirable to form the secondary air flow passage 121.
2 ≦ [(Wr + Wl−Wra−Wla) · H3 / S] · 100 ≦ 10 (3)
This condition is the sum of the area of the opening to the furnace 11 of the secondary air flow passage 121 located on the right and left of the fuel gas flow passage 111 of this embodiment (Wr + Wl) · H3 from the fuel gas of the comparative example An opening for blowing secondary air to the furnace 11 with a value obtained by subtracting the sum (Wra + Wla) · H3 of the area of the opening to the furnace 11 of the secondary air flow path 121a located on the right and left of the flow path 111 2% or more and 10% or less of the total area of the part.

When the total area S of the openings for blowing the secondary air blown by the blower 38 to the furnace 11 is constant, the flow rate of the secondary air supplied to the secondary air passage 121 is increased. The same amount of secondary air as the flow rate is reduced from the secondary air supply ports 130A and 130B. This is because the secondary air supplied to the secondary air flow path 121 and the secondary air supplied to the secondary air supply ports 130A and 130B are connected to the air box 36 which is the same supply source. It is.

The operation and effect of the combustion burner 100A of the present embodiment described above will be described.

According to the combustion burner 100A of the present embodiment, the flow of the opening to the furnace 11 of the secondary air flow path 121 located on the right and left of the fuel gas flow path 111 for supplying the pulverized fuel mixture to the furnace 11 The total of the channel widths is larger than the total of the channel widths of the openings to the furnace 11 of the secondary air channels 121 located above and below the fuel gas channel 111. Therefore, the flow rate of the secondary air supplied to the furnace 11 from the right side and the left side of the fuel gas flow path 111 where the secondary air supply ports 130A and 130B are not disposed is increased, and the right or left side of the combustion burner 100A. Hydrogen sulfide (H ₂ S) produced in the area adjacent to the furnace wall is reduced. This suppresses the corrosion of the furnace wall due to the generation of hydrogen sulfide. Further, according to the combustion burner 100A of the present embodiment, the flow rate of the secondary air supplied to the furnace 11 from the right side and the left side of the fuel gas flow path 111 where the secondary air supply ports 130A and 130B are not disposed is increased. It is possible to suppress the interference of flames of other adjacent combustion burners.

Further, in the combustion burner 100A of the present embodiment, the sum of the flow passage widths of the openings to the furnace 11 of the secondary air flow passage 121 located on the right and left of the fuel gas flow passage 111 is the fuel gas flow It is desirable that the total width of the flow passage width of the opening to the furnace 11 of the secondary air flow passage 121 located above and below the passage 111 be 1.5 times or more and 6 times or less.

The total of the channel widths of the openings of the secondary air channel 121 located to the right and left of the fuel gas channel 111 is the opening of the secondary air channel 121 located above and below the fuel gas channel 111 By making it sufficiently larger than the sum of the flow path width of the part, corrosion of the furnace wall due to generation of hydrogen sulfide in the area adjacent to the furnace wall and interference by flames of other adjacent combustion burners can be made more surely. It can be suppressed.

Other Embodiments
In the combustion burner 100A of the present embodiment, a flame holder may be disposed inside the tip of the fuel nozzle 110 facing the furnace 11. The flame holder is formed of, for example, one or more plate-like members extending along the vertical direction. By arranging the flame holder, the ignition performance and flame holding performance of the pulverized fuel mixture can be enhanced. The combustion burner 100A shown in FIGS. 7 and 8 is a modification in which three flame stabilizers 112 are disposed inside the tip of the fuel nozzle 110. The flame holder 112 is provided with an expanding member whose width in the horizontal direction is gradually expanded toward the furnace on the tip side (furnace side) of the plate member extending in the vertical direction.

When the flame stabilizer 112 is disposed inside the fuel nozzle 110, the ignition position is near the flame center of the combustion burner, so generation of NOx can be suppressed even if the amount of air in the secondary air flow passage 121 is increased. it can. In addition, consumption of oxygen in the secondary air supplied from the secondary air flow path 121 is also gradual, and corrosion suppression of the furnace wall due to the generation of hydrogen sulfide in the region adjacent to the furnace wall can be maintained.

DESCRIPTION OF SYMBOLS 10 pulverized coal burning boiler 11 furnace 12 combustion apparatus 26, 27, 28, 29, 30 pulverized coal supply pipe (fuel supply pipe)
31, 32, 33, 34, 35 Pulverized coal machine (crusher)
36 air box 37 air duct (secondary air supply pipe)
38 Blower 49 air heater (heat exchanger)
100A, 100B, 100C, 100D, 100E combustion burner 110 fuel nozzle 111 fuel gas passage 112 flame holder 120 secondary air nozzle 121 secondary air passage 130A, 130B secondary air supply port

Claims (4)

A fuel nozzle that forms a fuel gas flow path that extends in a cylindrical shape along an axis and supplies a fuel gas obtained by mixing a fuel obtained by grinding a carbon-containing solid fuel and primary air to a furnace;
A secondary air nozzle extending in a cylindrical shape along the axis and forming a secondary air flow path for supplying secondary air to the furnace from the outside of the fuel nozzle;
And a pair of secondary air supply ports disposed above and below the secondary air nozzle and supplying secondary air to the furnace.
The fuel gas flow channel and the secondary air flow channel are flow channels each having a rectangular cross section orthogonal to the axis,
The sum of the channel widths of the opening to the furnace of the secondary air channel located on the right and left of the fuel gas channel is the secondary located above and below the fuel gas channel A combustion burner which is larger than the sum of the flow passage widths of the openings to the furnace of the air flow passage. The channel width of the opening to the furnace of the secondary air channel located to the right of the fuel gas channel is the furnace of the secondary air channel located to the left of the fuel gas channel A combustion burner as claimed in claim 1, equal to the flow passage width of the opening to the combustion chamber. The sum of the channel widths of the opening to the furnace of the secondary air channel located on the right and left of the fuel gas channel is the secondary located above and below the fuel gas channel The combustion burner according to claim 1 or 2, which is not less than 1.5 times and not more than 6 times the total of the flow passage width of the opening to the furnace of the air flow passage. A furnace installed along the vertical direction and formed by four wall surfaces,
The combustion burner according to claim 1 or 2, installed for each of the four wall surfaces of the furnace.
A boiler, wherein the combustion burner blows the fuel gas at an angle with respect to the center of the furnace to form a swirling flow that swirls around the center of the furnace.

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