JP7139095B2 - boiler - Google Patents

Description

TECHNICAL FIELD The present invention relates to a boiler for generating steam for power generation, factories, or the like.

Conventionally, a solid fuel-fired burner is known which includes a fuel burner for charging pulverized coal and primary air into the furnace and a secondary port for the fuel burner for injecting secondary air from the outer periphery of the fuel burner (for example, patent Reference 1). The solid fuel-fired burner of Patent Literature 1 has a pair of secondary air injection ports arranged 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 the secondary port for the fuel burner. Therefore, the areas above and below the flame formed by the fuel burner have a relatively large amount of air relative to the fuel.
On the other hand, the solid fuel-fired burner of Patent Document 1 does not have secondary air input ports on the left and right sides of the secondary port for the fuel burner. Therefore, the right and left sides of the flame formed by the fuel burner are areas where the amount of air relative to the fuel is relatively small.

Japanese Patent Application Laid-Open No. 2015-200500

In the solid fuel-fired burner of Patent Document 1, when the right and left sides of the flame formed by the fuel burner become regions of a reducing atmosphere with a relatively small amount of air relative to the fuel, the adjacent furnace walls are likely to be corroded. There is a problem. 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 region of the reducing atmosphere.

In addition, the boiler equipped with solid fuel-fired burners disclosed in Patent Document 1 employs a swirling combustion system in which solid fuel-fired burners are arranged at four corner portions. Therefore, there is a possibility that the flame of the solid fuel-fired burner on the upstream side in the turning direction interferes with the flame of the solid fuel-fired burner on the downstream side, hindering combustion and deteriorating the combustion characteristics.

An object of the present invention is to solve the above-described problems, and to provide a boiler equipped with a combustion burner capable of suppressing corrosion of the furnace wall due to the generation of hydrogen sulfide and interference by flames of other adjacent combustion burners. With the goal.

The combustion burner provided in the boiler of the present invention for achieving the above object extends cylindrically along the axis and supplies fuel gas obtained by mixing fuel obtained by pulverizing carbon-containing solid fuel and primary air to the furnace. a fuel nozzle forming a fuel gas flow path; a secondary air nozzle extending cylindrically along the axis and forming a secondary air flow path for supplying secondary air from the outside of the fuel nozzle to the furnace; a pair of secondary air supply ports disposed above and below the secondary air nozzle for supplying secondary air to the furnace, wherein the fuel gas flow path and the secondary air flow path extend along the axis; The cross section perpendicular to the is a rectangular channel, and the sum of the channel widths of the openings to the furnace of the secondary air channels located to the right and left of the fuel gas channel is the fuel To the right and left of the secondary air nozzles, which are larger than the sum of the channel widths of the openings to the furnace of the secondary air channels located above and below the gas channel, and to the furnace No other secondary air supply port is provided to supply secondary air.

According to the boiler of the present invention, the sum of the channel widths of the openings to the furnace of the secondary air channels located to the right and left of the fuel gas channel for supplying the fuel gas to the furnace is equal to the fuel gas flow. greater than the sum of the channel widths of the openings to the furnace of the secondary air channels located above and below the channel. Therefore, the flow rate of the secondary air supplied to the furnace from the right and left sides of the fuel gas passage where the secondary air input port is not arranged increases, and the area adjacent to the furnace wall on the right or left side of the combustion burner Hydrogen sulfide (H2S) produced at is reduced. This suppresses corrosion of the furnace wall due to generation of hydrogen sulfide. Further, according to the boiler of the present invention, the flow rate of the secondary air supplied to the furnace from the right and left sides of the fuel gas passage where the secondary air input port is not arranged is increased, and the flow rate of the other adjacent combustion burners is increased. Flame interference can be suppressed.

In the boiler of the present invention, the passage width of the opening of the secondary air passage located on the right side of the fuel gas passage to the furnace is equal to the width of the second air passage located on the left side of the fuel gas passage. It may be equal to the channel width of the opening of the secondary air channel to the furnace.
The channel width of the opening of the secondary air channel located on the right side of the fuel gas channel and the channel width of the opening of the secondary air channel located on the left side of the fuel gas channel should be matched. As a result, corrosion of the furnace wall due to generation of hydrogen sulfide in the region adjacent to the furnace wall and interference due to flames of other adjacent combustion burners can be appropriately suppressed.

In the boiler of the present invention, the total channel width of the openings to the furnace of the secondary air channels positioned to the right and left of the fuel gas channel is above and below the fuel gas channel. not less than 1.5 times and not more than 6 times the total width of the passages of the openings to the furnace of the secondary air passages located at .

The boiler of the present invention comprises a furnace installed along the vertical direction and formed by four wall surfaces, and any one of the above combustion burners installed on each of the four wall surfaces of the furnace. The combustion burner blows the fuel gas at an angle with respect to the center of the furnace to form a swirling flow swirling around the center of the furnace.

According to the boiler of the present invention, in each of the combustion burners installed on each of the four wall surfaces of the furnace so as to form a swirl flow, the fuel gas flow path for supplying the fuel gas to the furnace The sum of the flow channel widths of the openings to the furnace of the secondary air flow channels positioned toward the front is the sum of the flow channel widths of the openings to the furnace of the secondary air flow channels positioned above and below the fuel gas flow channel. Greater than sum. Therefore, the flow rate of the secondary air supplied to the furnace from the right and left sides of the fuel gas passage where the secondary air input port is not arranged increases, and the area adjacent to the furnace wall on the right or left side of the combustion burner The hydrogen sulfide (H ₂ S) produced at is reduced. This suppresses corrosion of the furnace wall due to generation of hydrogen sulfide. Further, according to the boiler of the present invention, the flow rate of the secondary air supplied to the furnace from the right and left sides of the fuel gas passage where the secondary air input port is not arranged is increased, and the flow rate of the other adjacent combustion burners is increased. Flame interference can be suppressed.

ADVANTAGE OF THE INVENTION According to this invention, the boiler provided with the combustion burner which can suppress the corrosion of the furnace wall by generation of hydrogen sulfide, and interference by the flame of another adjacent combustion burner can be provided.

1 is a schematic configuration diagram showing a pulverized coal-fired boiler to which a combustion burner of one embodiment of the present invention is applied; FIG. Fig. 2 is a plan view showing a combustion burner in the pulverized coal-fired boiler shown in Fig. 1; 2 is a partial longitudinal sectional view of the combustion burner shown in FIG. 1; FIG. 3 is a front view of the combustion burner shown in FIG. 2 as seen from the furnace; FIG. 5 is a front view showing the channel width of the opening of the secondary air channel of the combustion burner shown in FIG. 4; FIG. FIG. 5 is a front view showing the channel width of the opening of the secondary air channel of the combustion burner of the comparative example;

Preferred embodiments of the combustion burner of the present invention will be described in detail below with reference to the accompanying drawings. It should be noted that the present invention is not limited by this embodiment, and when there are a plurality of embodiments, the invention also includes a configuration in which each embodiment is combined.

A pulverized coal-fired boiler to which a combustion burner of one embodiment of the present invention is applied uses pulverized coal as a carbon-containing solid fuel, burns this pulverized coal with a combustion burner, and dissipates the heat generated by this combustion. It is a boiler that can be recovered.

As shown in FIG. 1 , a pulverized coal-fired boiler 10 of this embodiment is a conventional boiler and has a furnace 11 , a combustion device 12 and a flue 13 . The furnace 11 has a hollow rectangular tubular shape and is installed along the vertical direction.

Combustion device 12 has a plurality of combustion burners 100A, 100B, 100C, 100D, 100E mounted on the furnace wall. In this embodiment, four combustion burners 100A, 100B, 100C, 100D, and 100E are arranged at equal intervals along the circumferential direction with the vertical direction in which the furnace 11 extends as one set. , are arranged in five sets (five stages) along the vertical direction. Although five sets are used here, six sets or any other number of sets may be used.

Each of the combustion burners 100A, 100B, 100C, 100D, and 100E feeds coal pulverizers (mills; pulverizers) 31, 32, 33, 34, and 35 via pulverized coal supply pipes 26, 27, 28, 29, and 30. connected to Although not shown, the coal pulverizers 31, 32, 33, 34, and 35 have a grinding table rotatably supported in a housing with an axis of rotation along the vertical direction. A plurality of crushing rollers are rotatably supported in conjunction with the rotation of the crushing table. Therefore, when coal is put between the pulverizing rollers and the pulverizing table, pulverized coal is pulverized to a predetermined size here, and the pulverized coal classified by the conveying air (primary air) is fed to the pulverized coal supply pipe 26, 27, 28, 29, 30 to combustion burners 100A, 100B, 100C, 100D, 100E.

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

Therefore, in the combustion device 12, each of the combustion burners 100A, 100B, 100C, 100D, and 100E feeds a pulverized fuel mixture (fuel gas), which is a mixture of pulverized coal and carrier air (primary air), into the furnace 11. In addition to being able to blow in, combustion air can be blown into the furnace 11 . Combustion device 12 may form a flame by igniting the pulverized fuel mixture with an ignition torch (not shown).

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

The flue 13 is connected to an exhaust gas pipe 48 through which combustion gas that has undergone heat exchange is discharged as exhaust gas on the downstream side of the gas flow. An air heater 49 is provided between the exhaust gas pipe 48 and the air duct 37, and heat exchange is performed 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 combustion air supplied to 100D and 100E can be heated. Although not shown, the exhaust gas pipe 48 is provided with a denitration device, an electric dust collector, an induced draft fan, and a desulfurization device, and a chimney is provided at the downstream end.

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

Then, the combustion burners 100A, 100B, 100C, 100D, and 100E blow a pulverized fuel mixture (fuel gas) in which pulverized coal and carrier air are mixed into the furnace 11, and blow combustion air into the furnace 11. At this time, A flame can be formed by igniting the Further, the additional air nozzle 39 blows additional air into the furnace 11 to perform combustion control to optimize the amount of air relative to the pulverized coal. In the furnace 11, the pulverized fuel mixture and the combustion air are combusted to generate a flame, and when the flame is generated in the vertically lower region of the furnace 11, combustion gas (exhaust gas) rises within the furnace 11. and discharged into the flue 13.

That is, the combustion burners 100A, 100B, 100C, 100D, and 100E blow a pulverized coal mixture and combustion air (secondary air) into the combustion area in the furnace 11, and ignite at this time to create a flame swirling flow in the combustion area. is formed. Then, this flame swirling flow rises while swirling and reaches the reduction region. Additional air nozzles 39 blow additional air vertically above the reduction zone in furnace 11 . In the furnace 11, the amount of air supplied is set to be less than the theoretical amount of air with respect to the amount of pulverized coal supplied, so that the inside is maintained in a reducing atmosphere. Then, the NOx generated by the combustion of the pulverized coal is reduced in the furnace 11, and then 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. reduced.

At this time, the water supplied from the feed water pump (not shown) is preheated by the economizers 45, 46, 47, then supplied to the steam drum (not shown) and supplied to each water pipe (not shown) on the furnace wall. While being heated, it becomes saturated steam and is sent to the steam drum. Further, the saturated steam in the steam drum is introduced into superheaters 41, 42 and superheated 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. Also, the steam extracted in the middle of the expansion process of the supplied steam in the turbine is introduced into the reheaters 43 and 44, heated again, returned to the turbine and expanded, and the turbine is driven to rotate. Although the furnace 11 has been described 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, and 47 in the flue 13 passes through an exhaust gas pipe 48, and a denitrification device (not shown) removes harmful substances such as NOx with supplied ammonia and a catalyst. Particulate matter is removed by an electrostatic precipitator, sulfur content is removed by a desulfurizer, and then discharged into the atmosphere through a chimney.

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

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

Therefore, the combustion burners 100Aa, 100Ab, 100Ac, and 100Ad on each wall surface of the furnace 11 supply the furnace 11 with a pulverized fuel mixture, which is a mixture of pulverized coal and carrier air (primary air). The combustion air (secondary air) is blown to the outside of the pulverized fuel mixture while providing a slight declination to the air. By igniting the pulverized fuel mixture from each of the combustion burners 100Aa, 100Ab, 100Ac, and 100Ad, four flames F1, F2, F3, and F4 can be formed. becomes a flame swirling flow swirling counterclockwise when viewed from above the furnace 11 (in FIG. 2). Here, the combustion burners 100Aa, 100Ab, 100Ac, and 100Ad may be arranged so that the flame swirls in the clockwise direction, although the flame swirls in the counterclockwise direction.

Next, the combustion burner 100A will be explained 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. , provided. In addition, the vertical cross-sectional view of FIG. 3 is a cross-sectional view of the combustion burner 100A shown in FIG.

Fuel nozzle 110 is a member formed to extend cylindrically along axis X1. The fuel nozzle 110 forms therein a fuel gas flow path 111 for supplying the pulverized fuel mixture supplied from the pulverized coal supply pipe 26 to the furnace 11 . The fuel gas channel 111 has a rectangular cross section perpendicular to the axis X1.

The opening of the fuel nozzle 110 facing the furnace 11 has a shape extending straight in the same direction as the gas flow direction of the pulverized fuel mixture. As shown in FIG. 3, the vertical height 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 X1) of the fuel gas flow path 111 .

The secondary air nozzle 120 is a member that is formed to extend cylindrically along the axis X1 and that surrounds the outside of the fuel nozzle 110 with respect to the axis X1. The secondary air nozzle 120 forms an annular secondary air flow path 121 for supplying secondary air to the furnace 11 between its inner peripheral surface and the outer peripheral surface of the fuel nozzle 110 . The secondary air flow path 121 has a rectangular cross section perpendicular to the axis X1.

The secondary air nozzle 120 supplies the secondary air supplied from the wind box 36 to the furnace 11 through the secondary air flow path 121 . The vertical height of the secondary air nozzle 120 is constant at H2 on the base end side, and decreases from H2 to H3 on the tip end side.

The secondary air supply port 130</b>A is arranged vertically above the secondary air nozzle 120 and supplies secondary air to the furnace 11 . The secondary air supply port 130</b>B is arranged vertically below the secondary air nozzle 120 and supplies secondary air to the furnace 11 . The secondary air supply ports 130A, 130B supply the secondary air supplied from the wind box 36 to the furnace 11. The height of the secondary air supply ports 130A and 130B is constant at H4 on the base end side and decreases from H4 to H5 on the tip end side.

Next, the channel width of the opening of the secondary air channel 121 to the furnace 11 will be described. FIG. 5 is a front view showing the channel width of the opening of the secondary air channel 121 of the combustion burner 100A shown in FIG. where W1 is the horizontal width of the fuel nozzle 110 opening and W2 is the horizontal width of the secondary air nozzle 120 opening.

Here, the channel width of the opening of the secondary air channel 121 located on the right side of the fuel gas channel 111 to the furnace 11 is Wr, and the secondary air channel located on the left side of the fuel gas channel 111 is Wr. Let Wl be the channel width of the opening of the channel 121 to the furnace 11 . Further, the width of the opening of the secondary air flow path 121 located above the fuel gas flow path 111 to the furnace 11 is Hu, and the width of the secondary air flow path 121 located below the fuel gas flow path 111 is Hu. Let Hd be the channel width of the opening to the furnace 11 .

In this 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)
This condition is that the sum of the channel widths of the openings to the furnace 11 of the secondary air channels 121 positioned to the right and left of the fuel gas channel 111 is positioned above and below the fuel gas channel 111. is larger than the sum of the channel widths of the openings of the secondary air channels 121 to the furnace 11 . By satisfying conditional expression (1), the flow rate of the secondary air supplied to the furnace from the right and left sides of the fuel gas passage 111 where the secondary air supply ports 130A and 130B are not arranged increases.

Here, the fuel gas channel 111 and the secondary air channel 121 may be formed so that Wr and Wl have the same channel width. Match the channel width Wr of the secondary air channel 121 located on the right side of the fuel gas channel 111 with the channel width Wl of the secondary air channel 121 located on the left side of the fuel gas channel 111 As a result, corrosion of the furnace wall due to generation of hydrogen sulfide in the region adjacent to the furnace wall and interference due to flames of other adjacent combustion burners can be appropriately suppressed.

Further, the fuel gas channel 111 and the secondary air channel 121 may be formed so that the channel widths Wr and Wl are different. 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 arranged on the left side of the fuel gas flow path 111, and the furnace wall is arranged from the right side of the fuel gas flow path 111. Interference by the flame of another combustion burner 100A on the upstream side of the swirling flow is received.

Therefore, when the influence of corrosion of the furnace wall due to the generation of hydrogen sulfide is greater than the flame interference, it is desirable to make Wl wider than Wr. By increasing the amount of secondary air supplied from the secondary air flow path 121 located on the left side of the fuel gas flow path 111, corrosion of the furnace wall due to generation of hydrogen sulfide can be suppressed.

Further, when the influence of 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 the secondary air supplied from the secondary air flow path 121 located on the right side of the fuel gas flow path 111, it is possible to suppress the interference of the flames of the other combustion burners 100A on the upstream side of the swirling flow. can.

Further, in this embodiment, it is desirable to form the fuel gas channel 111 and the secondary air channel 121 so that the following conditional expression (2) holds.
1.5≦(Wr+Wl)/(Hu+Hd)≦6 (2)
This condition is that the width of the openings of the secondary air flow paths 121 located to the right and left of the fuel gas flow path 111 to the furnace 11 is positioned above and below the fuel gas flow path 111. The condition is that it is 1.5 times or more and 6 times or less of the channel width of the opening of the secondary air channel 121 to the furnace 11 . By setting the conditional expression (2) to hold, the width of the openings of the secondary air flow path 121 located on the right and left sides of the fuel gas flow path 111 can be adjusted to be above and below the fuel gas flow path 111. can be sufficiently larger than the channel width of the opening of the secondary air channel 121 located at .

Here, a combustion burner of a 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 opening of the fuel nozzle 110 facing the furnace 11 has a rectangular shape with a width W1 and a height H1.

The combustion burner 100A of the present embodiment differs from the combustion burner of the comparative example in the shape of the secondary air nozzle 120 . The secondary air nozzle 120 of the present embodiment and the secondary air nozzle 120a of the comparative example have the same opening height 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 this embodiment. In the comparative example, the channel width Wra of the opening of the secondary air channel 121 a located on the right side of the fuel gas channel 111 to the furnace 11 and the secondary air channel located on the left side of the fuel gas channel 111 The sum of the channel width Wla of the opening of the passage 121a to the furnace 11, the channel width Hu of the opening of the secondary air channel 121 located above the fuel gas channel 111 to the furnace 11, and the fuel gas flow It is equal to the total channel width Hd of the opening of the secondary air channel 121 located below the channel 111 to the furnace 11 .

In this way, the total channel width (Wr+Wl) of the openings to the furnace 11 of the secondary air channels 121 located on the right and left sides of the fuel gas channel 111 of the present embodiment is the fuel of the comparative example. It is larger than the total channel width (Wra+Wla) of the openings to the furnace 11 of the secondary air channels 121 a positioned to the right and left of the gas channel 111 .

Here, when the total area of the openings for blowing the secondary air blown by the blower 38 to the furnace 11 is S, the fuel gas flow path 111 and It is desirable to form a secondary air flow path 121 .
2≦[(Wr+Wl−Wra−Wla)・H3/S]・100≦10 (3)
This condition is obtained from the total area (Wr+Wl)·H3 of the openings to the furnace 11 of the secondary air flow paths 121 located on the right and left sides of the fuel gas flow path 111 of the present embodiment, and the fuel gas of the comparative example. The value obtained by subtracting the sum of the areas of the openings to the furnace 11 (Wra + Wla) H3 of the secondary air flow paths 121a located on the right and left sides of the flow path 111 is the opening for blowing the secondary air to the furnace 11. 2% or more and 10% or less of the total area of the part.

In addition, when the total area S of the openings for blowing the secondary air blown by the blower 38 to the furnace 11 is constant, if the flow rate of the secondary air supplied to the secondary air flow path 121 is increased, The same amount of secondary air as the increased 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 same supply source, the wind box 36. is.

The operation and effects of the combustion burner 100A of this embodiment described above will be described.

According to the combustion burner 100A of the present embodiment, the openings of the secondary air flow paths 121 located to the right and left of the fuel gas flow path 111 that supplies the pulverized fuel mixture to the furnace 11 flow into the furnace 11. The total passage width is greater than the total passage width of the openings of the secondary air passages 121 located above and below the fuel gas passage 111 to the furnace 11 . Therefore, the flow rate of the secondary air supplied to the furnace 11 from the right and left sides of the fuel gas flow path 111, where the secondary air supply ports 130A and 130B are not arranged, increases. Less hydrogen sulfide ( _H2S ) is produced in the area adjacent to the furnace wall. This suppresses corrosion of the furnace wall due to 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 and left sides of the fuel gas flow path 111 where the secondary air supply ports 130A and 130B are not arranged increases. , the interference by the flames of other adjacent combustion burners can be suppressed.

Further, in the combustion burner 100A of the present embodiment, the total channel width of the openings to the furnace 11 of the secondary air channels 121 located on the right and left sides of the fuel gas channel 111 is equal to the fuel gas flow. It is desirable to set the width to 1.5 times or more and 6 times or less of the total width of the openings of the secondary air passages 121 located above and below the passage 111 to the furnace 11 .

The sum of the channel widths of the openings of the secondary air flow channels 121 positioned to the right and left of the fuel gas flow channel 111 is equal to the openings of the secondary air flow channels 121 positioned above and below the fuel gas flow channel 111. By making it sufficiently larger than the sum of the widths of the passages of the parts, corrosion of the furnace wall due to generation of hydrogen sulfide in the area adjacent to the furnace wall and interference by the flames of other adjacent combustion burners are more reliably prevented. can be suppressed.

<Other embodiments>
In the combustion burner 100A of this embodiment, a flame stabilizer may be arranged inside the tip of the fuel nozzle 110 facing the furnace 11 . The flame stabilizer is formed of, for example, one or more plate-like members extending in the vertical direction. By arranging the flame stabilizer, the ignition performance and flame holding performance of the pulverized fuel mixture can be enhanced.

10 pulverized coal-fired boiler 11 furnace 12 combustion device 26, 27, 28, 29, 30 pulverized coal supply pipe (fuel supply pipe)
31, 32, 33, 34, 35 Coal pulverizer (pulverizer)
36 wind 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 channel 120 Secondary air nozzle 121 Secondary air channel 130A, 130B Secondary air supply port

Claims (2)

a furnace installed along the vertical direction and formed by four wall surfaces;
a combustion burner installed against each of the four walls of the furnace;
A boiler in which the combustion burner blows fuel gas at an angle to the center of the furnace to form a swirling flow that swirls around the center of the furnace,
The combustion burner is
a fuel nozzle extending cylindrically along an axis and forming a fuel gas flow path for supplying the fuel gas, which is a mixture of fuel obtained by pulverizing carbon-containing solid fuel and primary air, to the furnace;
a secondary air nozzle extending cylindrically along the axis and forming a secondary air flow path for supplying secondary air from the outside of the fuel nozzle to the furnace;
a pair of secondary air supply ports disposed above and below the secondary air nozzle to supply secondary air to the furnace;
the fuel gas channel and the secondary air channel are channels having a rectangular cross section orthogonal to the axis;
The sum of the channel widths of the openings of the secondary air channels located to the right and left of the fuel gas channel to the furnace is equal to the secondary air channel located above and below the fuel gas channel. 1.5 times or more and 6 times or less of the total width of the opening of the air flow path to the furnace,
A boiler in which no other secondary air supply ports for supplying secondary air to the furnace are arranged to the right and left of the secondary air nozzles. The furnace of the secondary air flow path positioned to the left of the fuel gas flow path, wherein the flow path width of the opening of the secondary air flow path to the furnace positioned to the right of the fuel gas flow path 2. A boiler according to claim 1, equal to the channel width of the opening to the.

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