JP2017142041A - Combustion burner, combustor, and boiler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a combustion burner, a combustor and a boiler that increase jet force of secondary air to suppress attenuation due to peripheral flame flow, and thereby surely supply secondary air to a combustion burner to secure excellent combustion situation.SOLUTION: A combustion burner includes: a fuel nozzle 51 configured to jet out combustion gas, obtained by mixing fuel and air, along a horizontal direction; and a secondary air nozzle 53 (53A, 53B) configured to jet out air along the horizontal direction on an upper side and a lower side in a vertical direction of the fuel nozzle 51. The secondary air nozzle 53 (53A, 53B) includes an air passage 53Aa, 53Ba, and a jet openings 53Ab, 53Bb provided on a downstream side in a flow direction of secondary air in the air passage 53Aa, 53Ba. The jet opening 53Ab, 53Bb is formed into such a shape different from a passage cross sectional shape of the air passage 53Aa, 53Ba.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a combustion burner that mixes and burns fuel and air, a combustion device that forms a flame flow with the combustion burner, and a boiler that generates steam from combustion gas generated by the combustion device.

  A conventional boiler has a furnace that is hollow and is installed in a vertical direction, and a plurality of combustion burners are arranged on the furnace wall in the circumferential direction and the vertical direction. In this furnace, a flue is connected to the upper part, and a heat exchanger for collecting the heat of the exhaust gas to generate steam is disposed in the flue. The combustion burner is supplied with a mixture of finely pulverized fuel obtained by pulverizing a fuel such as coal and primary air, and is supplied with high-temperature secondary air, and blows the mixture and secondary air into the furnace. To form a flame.

  As a combustion burner applied to such a boiler, for example, there is one described in Patent Document 1 below.

Japanese Patent No. 3674003 Japanese Patent No. 5629901

  A plurality of combustion burners are arranged at predetermined intervals along the circumferential direction on the furnace wall. The plurality of combustion burners eject a mixture of fuel and air into the furnace and eject secondary air to the outside thereof. At this time, by igniting the air-fuel mixture ejected from each combustion burner, a flame swirl flow is formed in the furnace, and the combustion gas rises while swirling. Therefore, the combustion burner is affected by the flow of the flame flow from below in the horizontal direction or the vertical direction at the air outlet of the air-fuel mixture or secondary air. The secondary air ejected from the outer peripheral side of the combustion burner is attenuated by the influence of the flow of the flame flow from the horizontal direction, and flows into the flame flow. Then, secondary air is not supplied to the air-fuel mixture ejected from the combustion burner, and combustion is inhibited.

  The present invention solves the above-described problem, and by suppressing the attenuation by the surrounding flame flow by increasing the jet power of the secondary air, the secondary air is reliably supplied to the combustion burner, and the good combustion state An object of the present invention is to provide a combustion burner, a combustion apparatus, and a boiler that ensure the above.

  In order to achieve the above object, a combustion burner according to the present invention includes a fuel nozzle that jets a fuel gas mixed with fuel and air along a horizontal direction, and air on an upper side and a lower side in the vertical direction of the fuel nozzle. A secondary air nozzle that jets along the horizontal direction, the secondary air nozzle having an air passage and a jet opening provided on the downstream side of the air passage in the air passage, The ejection opening has a shape in which the opening area in the vertical direction is different from the cross-sectional shape of the air passage.

  Therefore, the jet opening has a shape in which the opening area in the vertical direction is different from the cross-sectional shape of the air passage, so that the air jet in a region where the opening area of the jet opening is more square or closer to a circle is horizontal due to the flame flow. It becomes difficult to flow in the direction, and the secondary air can be reliably mixed with the fuel gas by maintaining the jet of air from the jet opening. As a result, the secondary air is reliably supplied to the combustion burner by increasing the jet power of the secondary air to suppress the attenuation due to the surrounding flame flow, and a good combustion state can be ensured.

  The combustion burner according to the present invention is characterized in that the ejection opening has a plurality of divided openings provided at predetermined intervals along a horizontal direction intersecting an air ejection direction.

  Therefore, by providing a plurality of divided openings at predetermined intervals along the horizontal direction intersecting the air ejection direction as the ejection openings, the vertical opening area of each divided opening is secured in a shape close to a square or a circle. The jet of air at each divided opening is less susceptible to the influence of the flame flow, and the mixing of fuel gas and secondary air can be ensured by maintaining the jet of air from the jet opening. .

  The combustion burner according to the present invention is characterized in that the plurality of divided openings communicate with each other through a connecting opening having a smaller opening area in the vertical direction than the divided openings.

  Therefore, by connecting the plurality of divided openings to each other through the connecting openings having a small opening area, it is possible to cool by flowing air over the entire area of the ejection openings, and it is possible to prevent seizure due to the flame.

  In the combustion burner of the present invention, the plurality of divided openings are arranged so as to be shifted in the vertical direction.

  Therefore, since the plurality of divided openings are arranged so as to be shifted in the vertical direction, the air ejected from the divided openings close to the fuel nozzle side is mixed with the fuel gas from the fuel nozzle and burned, so Generation of fuel can be suppressed. On the other hand, the air ejected from the divided opening separated from the fuel nozzle is ejected away from the fuel gas from the fuel nozzle, so that excess air can be suppressed and generation of NOx can be suppressed.

  In the combustion burner of the present invention, the divided opening arranged away from the fuel nozzle ejects air in a direction away from the fuel nozzle, and the divided opening arranged close to the fuel nozzle includes: Air is ejected in a direction approaching the fuel nozzle.

  Therefore, the air from the split opening spaced from the fuel nozzle is ejected in the direction away from the fuel nozzle, and the air from the split opening approaching the fuel nozzle is ejected in the direction approaching the fuel nozzle. By regulating the direction in which the air is ejected, the secondary air can be reliably supplied while the generation of unburned matter can be prevented while further suppressing the generation of NOx due to excess air.

  In the combustion burner of the present invention, the ejection opening is provided on one side in the horizontal direction intersecting the air ejection direction and on the other side in the horizontal direction intersecting the air ejection direction. And a second opening having a larger opening area in the vertical direction than one opening.

  Therefore, the second opening having a large opening area is provided by providing a first opening on one side in the horizontal direction and a second opening having a larger opening area in the vertical direction than the first opening on the other side in the horizontal direction. For example, by providing a second opening on the side where the flame flow is likely to act, the air jet from the jet opening in this region is maintained and early mixing with the fuel gas is suppressed. can do.

  The combustion burner according to the present invention is characterized in that the ejection opening is arranged to be shifted to one side in the horizontal direction intersecting the air ejection direction.

  Therefore, by disposing the jet opening on one side in the horizontal direction, for example, by providing the jet opening on the side where the flame flow is likely to act, the air jet from the jet opening in this region is maintained. Thus, early mixing with fuel gas can be suppressed.

In the combustion burner according to the present invention, the ejection openings are arranged on one side in the horizontal direction and have a large opening area in the vertical direction, and on the other side in the horizontal direction and have a small opening area in the vertical direction. And having two openings.
Therefore, for example, by providing the first opening on the side where the flame flow is likely to act, it is possible to maintain the jet of air from the ejection opening in this region and suppress early mixing with the fuel gas.

  The combustion burner of the present invention is characterized in that a flame holder is provided at the tip of the fuel nozzle.

  Accordingly, the penetrating force of the secondary air ejected through the ejection opening is improved by the shape of the ejection opening, so that the surrounding flames are prevented from reaching the tip of the fuel nozzle and prevent external ignition of the fuel gas. In addition, the flame holding performance of the internal flame holding by the flame holder can be improved.

  Moreover, the combustion apparatus of the present invention is characterized in that a plurality of the combustion burners are arranged at predetermined intervals in the circumferential direction to form a flame swirl flow.

  Therefore, a flame swirl flow is formed by ejecting fuel gas and secondary air from a plurality of combustion burners. Here, the jet opening has a shape in which the opening area in the vertical direction is different from the passage cross-sectional shape of the air passage, so that the jet of air in the region where the opening area of the jet opening is more square or closer to the circle is caused by the flame flow. It becomes difficult to flow in the horizontal direction, and the secondary air can be reliably mixed with the fuel gas by maintaining the jet of air from the jet opening. As a result, the secondary air is reliably supplied to the combustion burner by increasing the jet power of the secondary air to suppress the attenuation due to the surrounding flame flow, and a good combustion state can be ensured.

  Moreover, the boiler of this invention is equipped with the furnace which makes | forms a hollow shape and is installed along a perpendicular direction, and the said combustion apparatus, It is characterized by the above-mentioned.

  Accordingly, a plurality of combustion burners are arranged along the circumferential direction on the furnace wall, and a flame swirl flow is formed in the furnace by the fuel gas and air injected from each combustion burner. Here, the jet opening of the combustion burner has a shape in which the opening area in the vertical direction is different from the passage cross-sectional shape of the air passage, so that the jet of air in a region where the opening area of the jet opening is closer to a square or a circle is generated. It becomes difficult to flow in the horizontal direction due to the flame flow, and the secondary air can be reliably mixed with the fuel gas while maintaining the jet of air from the jet opening. As a result, the secondary air is reliably supplied to the combustion burner by increasing the jet power of the secondary air to suppress the attenuation due to the surrounding flame flow, and a good combustion state can be ensured.

  According to the combustion burner, the combustion apparatus, and the boiler of the present invention, a combustion burner is constituted by a fuel nozzle and a secondary air nozzle, an air passage and a jet opening are provided as the secondary air nozzle, and the jet opening is a passage cross-sectional shape of the air passage. Therefore, the secondary air is reliably supplied to the combustion burner by increasing the jet output of the secondary air and suppressing the attenuation due to the surrounding flame flow. The combustion status can be ensured.

FIG. 1 is a front view illustrating a combustion burner according to the first embodiment. FIG. 2 is a longitudinal sectional view of the combustion burner. 3 is a cross-sectional view taken along the line III-III in FIG. 4 is a cross-sectional view taken along the line IV-IV in FIG. FIG. 5 is a schematic configuration diagram illustrating the boiler according to the first embodiment. FIG. 6 is a plan view showing the arrangement configuration of the combustion burners. FIG. 7 is a front view showing the combustion burner of the second embodiment. FIG. 8 is a front view showing the combustion burner of the third embodiment. 9 is a cross-sectional view taken along the line IX-IX in FIG. 10 is a cross-sectional view taken along the line XX in FIG.

  Exemplary embodiments of a combustion burner, a combustion apparatus, and a boiler according to the present invention will be described below in detail with reference to the accompanying drawings. In addition, this invention is not limited by this embodiment, and when there are two or more embodiments, what comprises combining each embodiment is also included.

[First Embodiment]
FIG. 5 is a schematic configuration diagram showing the boiler of the first embodiment, and FIG. 6 is a plan view showing the arrangement configuration of the combustion burners.

  The boiler according to the first embodiment is a boiler that uses pulverized coal obtained by pulverizing coal as pulverized fuel (solid fuel), burns the pulverized fuel with a combustion burner, and recovers heat generated by the combustion. .

  In the first embodiment, as shown in FIG. 5, the boiler 10 includes a furnace 11, a combustion device 12, and a flue 13. The furnace 11 has a rectangular hollow shape and is installed along the vertical direction. The furnace wall constituting the furnace 11 is constituted by a heat transfer tube.

  The combustion device 12 is provided in a lower part of a furnace wall (heat transfer tube) constituting the furnace 11. This combustion apparatus 12 has a plurality of combustion burners 21, 22, 23, 24, 25 mounted on the furnace wall. In this embodiment, the combustion burners 21, 22, 23, 24, and 25 are arranged as four sets at equal intervals along the circumferential direction, and five sets along the vertical direction. Five stages are arranged. However, the shape of the furnace, the number of combustion burners in one stage, and the number of stages are not limited to this embodiment.

  The combustion burners 21, 22, 23, 24, 25 are connected to pulverizers (mills) 31, 32, 33, 34, 35 via fine fuel supply pipes 26, 27, 28, 29, 30. . In the furnace 11, a wind box 36 is provided at a mounting position of each combustion burner 21, 22, 23, 24, 25, and one end portion of an air duct 37 is connected to the wind box 36. A blower 38 is connected to the other end of the fan. Further, the furnace 11 is provided with an additional air nozzle 39 located above the mounting position of the combustion burners 21, 22, 23, 24, 25, and an additional air duct 40 branched from the air duct 37 is connected. Yes.

  The flue 13 is connected to the upper part of the furnace 11 and is provided with superheaters 41, 42, 43, reheaters 44, 45, and economizers 46, 47 as heat exchangers for recovering the heat of the combustion gas. It has been. The gas duct 48 of the flue 13 is provided with an air heater 49, which can raise the temperature of combustion air supplied to the combustion burners 21, 22, 23, 24, 25.

  Here, although the combustion apparatus 12 is demonstrated in detail, since the combustion burners 21, 22, 23, 24, and 25 which comprise this combustion apparatus 12 have comprised the substantially the same structure, respectively, the combustion burner 21 is represented. The arrangement configuration will be described.

  As shown in FIG. 6, the combustion burner 21 includes combustion burners 21 a, 21 b, 21 c, and 21 d provided on four wall portions in the furnace 11. Each combustion burner 21a, 21b, 21c, 21d is connected to each branch pipe 26a, 26b, 26c, 26d branched from the pulverized fuel supply pipe 26, and each branch pipe 37a, 37b, 37c branched from the air duct 37. , 37d are connected.

  Therefore, each combustion burner 21a, 21b, 21c, 21d blows a pulverized fuel mixture, which is a mixture of pulverized fuel and carrier air, into the furnace 11, and also provides combustion air around the pulverized fuel mixture. Infuse. Then, by igniting this pulverized fuel mixture, four flames F1, F2, F3, and F4 can be formed, and these flames F1, F2, F3, and F4 are viewed from vertically above the furnace 11 ( In FIG. 6), the flame swirl C swirls counterclockwise.

  Hereinafter, a specific configuration of each combustion burner 21 will be described in detail. 1 is a front view showing a combustion burner according to the first embodiment, FIG. 2 is a longitudinal sectional view of the combustion burner, FIG. 3 is a sectional view taken along line III-III in FIG. 1, and FIG. It is sectional drawing.

  As shown in FIGS. 1 and 2, the combustion burner 21 is provided with a fuel nozzle 51, a combustion air nozzle 52, and a secondary air nozzle 53 in order from the center O side, and a flame holder 54 in the fuel nozzle 51. It is provided and configured.

  The fuel nozzle 51 can eject a pulverized fuel mixture (hereinafter referred to as fuel gas) F obtained by mixing pulverized fuel (solid fuel) and carrier air (primary air) along the horizontal direction. The combustion air nozzle 52 is disposed outside the fuel nozzle 51, and a part of the combustion air (hereinafter referred to as fuel gas combustion air) A1 is horizontally disposed on the outer peripheral side of the fuel gas F injected from the fuel nozzle 51. Can erupt along. The secondary air nozzle 53 is disposed outside the combustion air nozzle 52, and a part of the combustion air (hereinafter referred to as secondary air) on the outer peripheral side of the fuel gas combustion air A1 ejected from the combustion air nozzle 52. A2 can be ejected along the horizontal direction. In the present embodiment, the secondary air nozzle 53 is disposed on the upper side in the vertical direction of the combustion air nozzle 52 and on the lower side in the vertical direction of the combustion air nozzle 52. It is comprised from the secondary air nozzle 53B.

  Here, the fuel nozzle 51 has a rectangular tube shape, and a concentric outer ring-shaped combustion air nozzle 52 is disposed on the outer side of the fuel nozzle 51, and a substantially rectangular shape is formed above and below the combustion air nozzle 52, respectively. Secondary air nozzles 53 (53A, 53B) are arranged. The fuel gas F from the fuel nozzle 51, the fuel gas combustion air A1 from the combustion air nozzle 52, and the secondary air A2 from the secondary air nozzle 53 are jetted in parallel along the horizontal direction. .

  Note that the above-described vertical direction includes a direction shifted by a minute angle with respect to the vertical direction. The secondary air nozzle 53 is disposed outside the combustion air nozzle 52 and at a position adjacent in the vertical direction, but may be disposed at a position adjacent in the horizontal direction or provided around the entire circumference. Good. Further, the secondary air nozzle 53 may be capable of adjusting the ejection amount of the secondary air by providing a damper opening adjustment mechanism or the like.

  The base end of the fuel nozzle 51 is connected to the tip of the pulverized fuel supply pipe 26, and the tip is exposed in the furnace 11. Combustion air nozzle 52 and secondary air nozzle 53 have base ends connected to wind box 36 (see FIG. 5) via connecting portions 71 and 72, and tip portions are exposed in furnace 11. . The combustion burner 21 has a nozzle portion 75 composed of a fuel nozzle 51, a combustion air nozzle 52 and a secondary air nozzle 53, and a conduit portion 76 composed of a pulverized fuel supply pipe 26 and connecting portions 71 and 72. . The angle of the nozzle portion 75 can be adjusted along the vertical direction by a support shaft (not shown) along the horizontal direction with respect to the duct portion 76 and the wind box 36. That is, the fuel nozzle 51, the combustion air nozzle 52, and the secondary air nozzle 53 can be adjusted so that the ejection direction is along the vertical direction. The nozzle portion 75 may be movable in the horizontal direction by a support shaft extending in the vertical direction with respect to the duct portion 76 and the wind box 36.

  The fuel nozzle 51 is a straight pipe and has a constant cross-sectional area (passage area) (passage area) perpendicular to the direction in which the fuel gas is ejected. The combustion air nozzle 52 has a shape that is narrowed toward the tip side, that is, toward the downstream end in the flow direction of the fuel gas combustion air. Therefore, in the combustion air nozzle 52, the area (passage area) of the cross section (passage) orthogonal to the direction in which the fuel gas combustion air is ejected becomes smaller toward the tip. The secondary air nozzle 53 has a shape that is narrowed toward the tip side, that is, toward the downstream end of the secondary air flow direction. Therefore, in the secondary air nozzle 53, the area (passage area) of the cross section (passage) orthogonal to the direction in which the secondary air is ejected becomes smaller toward the tip.

  The shapes of the openings of the fuel nozzle 51 and the combustion air nozzle 52 are not limited to a rectangle, and may be a square, a circle, or an ellipse. Further, when the combustion air nozzle 52 is rectangular, it may have a shape with a curved corner. By using a tubular structure with a curved corner, the strength of the nozzle can be improved.

  The flame holder 54 is disposed in the fuel nozzle 51 on the downstream side in the fuel gas ejection direction and on the center O side, and functions as an ignition and flame holding fuel gas. . The flame holder 54 is a so-called double cross in which first flame holding members 61 and 62 along the horizontal direction and second flame holding members 63 and 64 along the vertical direction are arranged so as to intersect in a cross shape. It has a split structure. Each of the first flame holding members 61 and 62 has a flat portion 61a and 62a having a flat plate shape with a constant thickness, and tip portions of the flat portions 61a and 62a (downstream end portions in the fuel gas flow direction). Are provided with widened portions 61b and 62b which are integrally provided. The widened portions 61b and 62b have an isosceles triangular cross section, the width is widened toward the downstream side in the fuel gas flow direction, and the tip is a plane perpendicular to the fuel gas flow direction. Although not shown, the second flame holding members 63 and 64 have the same structure.

  Therefore, the fuel nozzle 51 and the combustion air nozzle 52 have a long tubular structure, and the fuel nozzle 51 and the combustion air nozzle 52 have a double pipe structure. The fuel nozzle 51 has a fuel passage 51a through which fuel gas flows, and an ejection opening 51b having a rectangular shape provided at the downstream end of the fuel passage 51a in the fuel gas flow direction. The combustion air nozzle 52 has an air passage 52a through which fuel gas combustion air flows, and an ejection opening 52b that is provided on the downstream side in the flow direction of the air passage 52a and forms a rectangular ring shape. As for the fuel nozzle 51 and the combustion air nozzle 52, the secondary air nozzle 53A is arrange | positioned at the upper side of the outer side, and the secondary air nozzle 53B is arrange | positioned at the downward side. Each of the secondary air nozzles 53A and 53B has a long tubular structure, and includes air passages 53Aa and 53Ba through which the secondary air flows, and ejection openings 53Ab and 53Bb provided on the downstream side in the flow direction of the air passages 53Aa and 53Ba. Have.

  These nozzles 51, 52, and 53 are arranged such that the ejection openings 51b, 52b, 53Ab, and 53Bb are aligned on the same plane. The flame holder 54 is supported by a plate material (not shown) from the inner wall surface of the fuel nozzle 51 or the upstream side of the passage through which the fuel gas flows. Further, the fuel nozzle 51 has a plurality of flame holding members 61, 62, 63, 64 as flame holders 54 disposed therein, so that the fuel gas flow path is divided into nine. The flame holder 54 has widened portions 61b and 62b whose widths are widened at the front end portions, and the widened portions 61b and 62b have the front end surfaces aligned with the ejection opening 51b.

  In the present embodiment, the secondary air nozzle 53 (53A, 53B) has the ejection openings 53Ab, 53Bb having a different shape along the horizontal direction. Hereinafter, the secondary air nozzle 53 will be described in detail. Since the secondary air nozzle 53A on the upper side and the secondary air nozzle 53B on the lower side have a line-symmetric configuration, the secondary air nozzle 53A on the upper side. Only will be described.

  As shown in FIGS. 1, 3 and 4, the secondary air nozzle 53A has an air passage 53Aa and a jet opening 53Ab provided on the downstream side of the air passage 53Aa in the air flow direction. This ejection opening 53Ab has a shape different from the passage cross-sectional shape of the air passage 53Aa. That is, in the secondary air nozzle 53A, the air passage 53Aa has a rectangular cross-sectional shape that is long in the horizontal direction, but the ejection opening 53Ab has a shape in which the opening area in the vertical direction differs along the horizontal direction.

  More specifically, the ejection opening 53Ab is composed of a plurality (five in the present embodiment) of divided openings 81 and a plurality (four in the present embodiment) of connecting openings 82. The plurality of divided openings 81 form a quadrangle (square) and are provided at predetermined intervals along a horizontal direction intersecting with the secondary air ejection direction. The plurality of connection openings 82 have a quadrangular (rectangular) shape whose opening area in the vertical direction is smaller than that of each of the divided openings 81, and is provided so that the connection openings 81 communicate with each other between the plurality of divided openings 81. In other words, a part of the rectangular air passage 53Aa is closed to form an irregular ejection opening 53Ab. Here, the width (length in the horizontal direction) of each divided opening 82 is larger than the width (length in the horizontal direction) of each connection opening 82. The width of the ejection opening 53Ab in the secondary air nozzle 53A is the same as the width of the ejection opening 52b in the combustion air nozzle 52.

  In addition, although the division | segmentation opening 81 was made into square at ejection opening 53Ab, it may be a rectangle, a polygon, and it is good also as a circle, an ellipse, etc. In this case, by making the divided opening 81 circular, manufacturability is facilitated. Further, the number of the divided openings 81 and the connecting openings 82 is not limited to those described above, and may be set as appropriate. By reducing the number of the divided openings 81, one divided opening 81 can be enlarged, and the secondary air jet power can be increased. Furthermore, although the plurality of divided openings 81 are configured to communicate with each other through the plurality of connection openings 82, the connection openings 82 may be omitted and the ejection openings 853Ab may be configured with only the plurality of division openings 81.

  Similar to the secondary air nozzle 53A, the secondary air nozzle 53B has an air passage 53Ba (see FIG. 2) and a plurality of ejection openings 53Bb, and there are a plurality of ejection openings 53Bb (five in this embodiment). Divided openings 83 and a plurality (four in this embodiment) of connecting openings 84.

  In the combustion burner 21 configured in this manner, as shown in FIG. 2, the fuel gas F flows from the fine fuel supply pipe 26 to the fuel passage 51a of the fuel nozzle 51 and is ejected into the furnace from the ejection opening 51b. . The fuel gas combustion air A1 flows from the wind box 36 (see FIG. 1) through the connecting portion 71 to the air passage 52a of the combustion air nozzle 52, and is ejected to the outside of the fuel gas F from the ejection opening 51b. The secondary air A2 flows from the wind box 36 (see FIG. 1) through the connecting portion 72 to the air passages 53Aa and 53Ba of the secondary air nozzles 53A and 53B, and from the ejection openings 53Ab and 53Bb to the outside of the fuel gas combustion air A1. Is erupted. At this time, it is desirable that the fuel gas F, the fuel gas combustion air A1, and the secondary air A2 be ejected as a straight flow along the burner axial direction (center O) without turning.

  At this time, in the secondary air nozzles 53A and 53B, the ejection openings 53Ab and 53Bb have shapes different from the passage cross-sectional shapes of the air passages 53Aa and 53Ba. Therefore, when the secondary air flowing through the air passages 53Aa and 53Ba is ejected into the furnace through the ejection openings 53Ab and 53Bb, the secondary air at the ejection openings 53Ab and 53Bb is close to a square, so that the penetration force is improved. That is, since the ejection openings 53Aa and 53Bb have a large opening area in the vertical direction at each divided opening 81, the jet of secondary air at each divided opening 81 becomes strong, and the secondary air from each divided opening 81 becomes stronger. Early mixing with the fuel gas is suppressed by properly maintaining the air jet.

  The secondary air ejected from the outer peripheral side of the combustion burner 21 is easily affected by the flow of the flame swirl flow C (see FIG. 6) from the horizontal direction. However, in this embodiment, due to the shape of the secondary air nozzles 53A and 53B, the penetrating force is particularly strong because the secondary air in each of the divided openings 81 is nearly square. Therefore, the secondary air ejected from the secondary air nozzles 53A and 53B is difficult to flow in the direction of the flame flow, that is, the left side in FIG. Secondary air ejected from the secondary air nozzles 53A and 53B flows to an appropriate vertical position with respect to the fuel gas, and combustion is stabilized.

  Further, the fuel gas F branches and flows by the first flame holding members 61 and 62 and the second flame holding members 63 and 64 at the ejection opening 51b of the fuel nozzle 51, and is ignited and burned here, and the combustion gas It becomes. Further, the fuel gas F is promoted to burn the fuel gas F by ejecting the fuel gas combustion air A1 to the outer periphery. Further, the secondary air A2 is ejected to the outer periphery of the combustion flame, so that the ratio of the fuel gas combustion air A1 and the secondary air A2 can be adjusted, and optimal combustion without generating NOx can be obtained.

  In the flame holder 54, since the first flame holding members 61 and 62 and the second flame holding members 63 and 64 have a split shape, the fuel gas F flows along the widened portions 61b and 62b, and the front end surface. A recirculation region is formed forward by wrapping around. Therefore, the fuel gas F is ignited and held in this recirculation region, and internal combustion holding of the combustion flame (flaming holding in the center region on the center O side in the fuel nozzle 51) is realized. Then, the outer peripheral part of the combustion flame becomes a low temperature, and the temperature of the outer peripheral part of the combustion flame in a high oxygen atmosphere can be lowered by the secondary air A2, and the amount of NOx generated in the outer peripheral part of the combustion flame is reduced.

  As described above, in the combustion burner according to the first embodiment, the fuel nozzle 51 that ejects the fuel gas mixed with fuel and air along the horizontal direction, and the upper and lower sides of the fuel nozzle 51 in the vertical direction. A secondary air nozzle 53 (53A, 53B) for ejecting air along the horizontal direction is provided, and the secondary air nozzle 53 (53A, 53B) is secondary in the air passages 53Aa, 53Ba and the air passages 53Aa, 53Ba. It has ejection openings 53Ab and 53Bb provided on the downstream side in the air flow direction, and the ejection openings 53Ab and 53Bb have a shape in which the opening area in the vertical direction is different from the passage sectional shape of the air passages 53Aa and 53Ba. .

  Accordingly, since the vertical opening areas of the ejection openings 53Ab and 53Bb of the secondary air nozzle 53 (53A and 53B) have different shapes, the secondary air flowing through the air passages 53Aa and 53Ba is ejected through the ejection openings 53Ab and 53Bb. The air jets in the area where the opening areas of the jet openings 53Ab and 53Bb are more square or nearly circular are less likely to flow in the horizontal direction due to the flame flow swirl, and the jet of air from the jet openings 53Ab and 53Bb is maintained. Thus, the secondary air can be reliably mixed with the fuel gas. As a result, the secondary air is reliably supplied to the combustion burners 21, 22, 23, 24, and 25 by increasing the jet power of the secondary air and suppressing the attenuation caused by the surrounding flame swirl flow. Can be secured.

  In the combustion burner of the first embodiment, the ejection openings 53Ab, 53Bb have a plurality of divided openings 81, 83 provided at predetermined intervals along a horizontal direction intersecting the secondary air ejection direction. Therefore, the opening area in the vertical direction of each of the divided openings 81 and 83 can be secured in a square or a shape close to a circle, and the jet of air at each of the divided openings 81 and 83 is less affected by the flame swirl flow. It is possible to reliably ensure the mixing of the fuel gas and the secondary air by maintaining the jet of the secondary air from the ejection openings 53Ab and 53Bb.

  In the combustion burner according to the first embodiment, the plurality of divided openings 81 and 83 communicate with each other through connection openings 82 and 84 having a smaller opening area in the vertical direction than the divided openings 81 and 83. Accordingly, the plurality of divided openings 81 and 83 and the plurality of connection openings 82 and 84 communicate with each other as one opening, so that the secondary air can be flowed and cooled in the entire region of the ejection openings 53Ab and 53Bb, and the Burn-in can be prevented.

  In the combustion burner of the first embodiment, a flame holder 54 is provided at the tip of the fuel nozzle 51. Accordingly, the fuel gas ejected from the fuel nozzle 51 is branched and flows by the flame holder 54, and is ignited and burned therein to become combustion gas. On the other hand, the secondary air ejected from the secondary air nozzle 53 is less affected by the swirl of the flame because its penetration force is improved when passing through the ejection openings 53Ab and 53Bb. Therefore, external ignition by the flame swirl flow is prevented for the fuel gas from the fuel nozzle 51, and the flame holding performance of the internal flame holding by the flame holder 54 can be improved.

  Further, in the combustion apparatus of the first embodiment, a flame swirl flow can be formed by arranging a plurality of combustion burners 21, 22, 23, 24, 25 at predetermined intervals in the circumferential direction of the furnace 11. Yes. Accordingly, the fuel gas and the secondary air are ejected from the plurality of combustion burners 21, 22, 23, 24, 25, thereby forming a flame swirl flow. Here, since the opening areas in the vertical direction of the ejection openings 53Ab and 53Bb of the secondary air nozzle 53 (53A and 53B) are different, the opening areas of the ejection openings 53Ab and 53Bb are more square or in a region closer to a circle. The jet of air is less likely to flow in the horizontal direction due to the swirling of the flame flow, and the air jet from the jet openings 53Ab and 53Bb is maintained, so that the secondary air can be reliably mixed with the fuel gas. As a result, the secondary air is reliably supplied to the combustion burners 21, 22, 23, 24, and 25 by increasing the jet power of the secondary air and suppressing the attenuation caused by the surrounding flame swirl flow. Can be secured.

  Moreover, in the boiler of 1st Embodiment, the furnace 11 which makes | forms a hollow shape and is installed along a perpendicular direction, and the combustion apparatus 12 comprised from the combustion burners 21, 22, 23, 24, 25 are provided. I have. Therefore, a flame swirl flow can be formed in the furnace 11 by arranging the plurality of combustion burners 21, 22, 23, 24, 25 along the circumferential direction on the furnace wall. At this time, since the opening areas in the vertical direction of the ejection openings 53Ab and 53Bb of the secondary air nozzle 53 (53A and 53B) are different, the opening areas of the ejection openings 53Ab and 53Bb are more square or in a region closer to a circle. The jet of air is less likely to flow in the horizontal direction due to the swirling of the flame flow, and the air jet from the jet openings 53Ab and 53Bb is maintained, so that the secondary air can be reliably mixed with the fuel gas. As a result, the secondary air is reliably supplied to the combustion burners 21, 22, 23, 24, and 25 by increasing the jet power of the secondary air and suppressing the attenuation caused by the surrounding flame swirl flow. Can be secured.

[Second Embodiment]
FIG. 7 is a front view showing the combustion burner of the second embodiment. In addition, the same code | symbol is attached | subjected to the member which has the same function as embodiment mentioned above, and detailed description is abbreviate | omitted.

  In the second embodiment, as shown in FIG. 7, the combustion burner 21 is provided with a fuel nozzle 51, a combustion air nozzle 52, and a secondary air nozzle 91 in this order from the center O side. A device 54 is provided.

  The fuel nozzle 51 can eject the fuel gas along the horizontal direction. The combustion air nozzle 52 is arranged outside the fuel nozzle 51 and can eject the fuel gas combustion air along the horizontal direction to the outer peripheral side of the fuel gas. The secondary air nozzle 91 can inject secondary air along the horizontal direction above and below the fuel gas combustion air outside the combustion air nozzle 52. In the present embodiment, the secondary air nozzle 91 is disposed on the lower side in the vertical direction of the combustion air nozzle 52 and the secondary air nozzle 91 </ b> A disposed on the upper side in the vertical direction of the combustion air nozzle 52. And a secondary air nozzle 91B.

  In the secondary air nozzle 91 (91A, 91B), the ejection openings 91Ab, 91Bb have irregular shapes along the horizontal direction. The secondary air nozzles 91A and 91B have an air passage (not shown) and ejection openings 91Ab and 91Bb provided on the downstream side of the air passage in the air flow direction. The ejection openings 91Ab and 91Bb have different shapes with respect to the passage cross-sectional shape of the air passage. That is, in the secondary air nozzles 91A and 91B, the air passage has a rectangular cross-sectional shape that is long in the horizontal direction, but the ejection openings 91Ab and 91Bb have shapes that have different opening areas in the vertical direction along the horizontal direction. Yes.

  Specifically, the ejection openings 91Ab and 91Bb are provided with first openings 92 and 94 provided on one side (left side in FIG. 7) in the horizontal direction intersecting the ejection direction of the secondary air, and It has the 2nd opening 93,95 provided in the other side (right side in FIG. 7) in the horizontal direction which cross | intersects an ejection direction, and the opening area of a perpendicular direction is larger than the 1st opening 92,94. The first openings 92 and 94 and the second openings 93 and 95 each have a quadrangular shape (rectangular shape) and communicate with each other at the horizontal center position. For this reason, the first openings 92 and 94 and the second openings 93 and 95 have the same width (length in the horizontal direction). That is, odd-shaped ejection openings 91Ab and 91Bb are formed by blocking a part of the rectangular air passage.

  In this case, the arrangement relationship between the first openings 92 and 94 and the second openings 93 and 95 is such that the opening area in the vertical direction is on the upstream side (right side in FIG. 7) of the flame swirl flow formed by the four combustion burners 21. It is desirable to arrange the second openings 93 and 95 having a large.

  Although the first openings 92 and 94 and the second openings 93 and 95 divided openings 81 are rectangular in the ejection openings 91Ab and 91Bb, they may be polygonal, circular, elliptical, or the like. In addition, the jet openings 91Ab and 91Bb are configured by the two first openings 92 and 94 and the second openings 93 and 95, but may be configured by three or more openings having different opening areas in the vertical direction. Furthermore, although the first openings 92 and 94 and the second openings 93 and 95 communicate with each other at the center position in the horizontal direction, the communication positions may be shifted in the horizontal direction, and the first openings 92 and 94 and the second openings 93 and 95 may be displaced. Need not be communicated.

  Further, in the above-described embodiment, the ejection openings 91Ab and 91Bb are provided with the first openings 92 and 94 provided on one side in the horizontal direction, and the opening area in the vertical direction is provided on the other side with respect to the first openings 92 and 94. Although it comprised from the large 2nd opening 93,95, it is not limited to this structure. For example, the ejection opening may be provided by being shifted to one side in the horizontal direction intersecting the ejection direction of the secondary air. That is, the ejection opening may be configured by only the second openings 93 and 95, and in this case, the horizontal length of the ejection opening may be longer than that of the second openings 93 and 95.

  Therefore, the fuel gas is ejected from the fuel nozzle 51 into the furnace, the fuel gas combustion air is ejected from the combustion air nozzle 52 to the outside of the fuel gas, and the secondary air is ejected from the secondary air nozzles 91A and 91B. It is ejected outside the fuel gas combustion air. At this time, in the secondary air nozzles 91A and 91B, the ejection openings 91Ab and 91Bb have shapes different from the passage cross-sectional shape of the air passage. Therefore, when the secondary air flowing through the air passages 91Aa and 91Ba is ejected into the furnace through the ejection openings 91Ab and 91Bb, the secondary air at the ejection openings 91Ab and 91Bb is close to a square, so that the penetration force is improved. That is, since the ejection openings 91Ab and 91Bb are configured by the first openings 92 and 94 and the second openings 93 and 95 having different opening areas in the vertical direction, the jet of secondary air in the second openings 93 and 95 is generated. It becomes stronger, and the jet of the secondary air from the second openings 93 and 95 is properly maintained to ensure the mixing with the fuel gas.

  The secondary air ejected from the outer peripheral side of the combustion burner 21 is easily affected by the flow of the flame swirl flow C (see FIG. 6) from the horizontal direction. However, in this embodiment, the opening area in the vertical direction of the second openings 93 and 95 positioned on the upstream side of the flame swirl flow is set particularly large due to the shape of the secondary air nozzles 91A and 91B. Therefore, since the secondary air in the second openings 93 and 95 is almost square, the penetrating force is strong, and the secondary air ejected from the secondary air nozzles 91A and 91B is affected by the flame swirl flow. It becomes difficult to flow in the direction of the flame flow, and the secondary air ejected from the secondary air nozzles 91A and 91B flows to an appropriate vertical position with respect to the fuel gas ejected from the fuel nozzle 51, and the combustion is stabilized.

  Thus, in the combustion burner of 2nd Embodiment, the 1st opening provided in one side in the horizontal direction which cross | intersects the ejection direction of secondary air as ejection opening 91Ab, 91Bb of secondary air nozzle 91A, 91B. 92, 94 and second openings 93, 95 provided on the other side in the horizontal direction intersecting the secondary air ejection direction and having a larger opening area in the vertical direction than the first openings 92, 94.

  Accordingly, the jet of the secondary air from the second openings 93 and 95 having a large opening area in the vertical direction is strengthened, and the second openings 93 and 95 are arranged on the side where the flame swirl tends to act. The secondary air jet flow from the jet openings 91Ab and 91Bb can be maintained and the mixing of the fuel gas and the secondary air can be reliably ensured.

[Third Embodiment]
8 is a front view showing the combustion burner of the third embodiment, FIG. 9 is a cross-sectional view taken along the line IX-IX in FIG. 8, and FIG. In addition, the same code | symbol is attached | subjected to the member which has the same function as embodiment mentioned above, and detailed description is abbreviate | omitted.

  In the third embodiment, as shown in FIGS. 8 to 10, the combustion burner 21 is provided with a fuel nozzle 51, a combustion air nozzle 52, and a secondary air nozzle 101 in order from the center O side. A flame holder 54 is provided.

  The fuel nozzle 51 can eject the fuel gas along the horizontal direction. The combustion air nozzle 52 is arranged outside the fuel nozzle 51 and can eject the fuel gas combustion air along the horizontal direction to the outer peripheral side of the fuel gas. The secondary air nozzle 101 can eject secondary air along the horizontal direction above and below the fuel gas combustion air outside the combustion air nozzle 52. In the present embodiment, the secondary air nozzle 101 is disposed on the lower side in the vertical direction of the combustion air nozzle 52 and the secondary air nozzle 101 </ b> A disposed on the upper side in the vertical direction of the combustion air nozzle 52. It is comprised from the secondary air nozzle 101B.

  In the secondary air nozzle 101 (101A, 101B), the ejection openings 101Ab, 101Bb have irregular shapes along the horizontal direction. The secondary air nozzles 101A and 101B have an air passage 101Aa and ejection openings 101Ab and 101Bb provided on the downstream side of the air passage 101Aa in the air flow direction. The ejection openings 101Ab and 101Bb have different shapes from the passage cross-sectional shape of the air passage 101Aa. That is, in the secondary air nozzles 101A and 101B, the air passage 101Aa has a rectangular cross-sectional shape that is long in the horizontal direction, but the ejection openings 101Ab and 101Bb have shapes in which the opening positions in the vertical direction are different along the horizontal direction. ing.

  Specifically, the ejection opening 101Ab is configured by a plurality (five in this embodiment) of divided openings 102 and 103, and the ejection opening 101Bb is a plurality of (five in the present embodiment) divided openings 104. , 105. The plurality of divided openings 102, 103, 104, 105 form a quadrilateral (rectangular shape) and are provided side by side along a horizontal direction that intersects the secondary air ejection direction. In the ejection opening 101Ab, the divided openings 102 and 103 are shifted in the vertical direction, and in the ejection opening 101Bb, the divided openings 104 and 105 are shifted in the vertical direction. That is, when the air passages 101Aa and 101Ba having a rectangular shape are partially closed, the odd-shaped ejection openings 101Ab and 101Bb are formed.

  Further, the divided openings 103 and 105 arranged away from the fuel nozzle 51 eject secondary air in a direction away from the fuel nozzle 51, and the divided openings 102 and 104 arranged close to the fuel nozzle 51 are arranged. Secondary air is ejected in a direction approaching the fuel nozzle 51. That is, in the ejection opening 101Ab, each of the divided openings 102 arranged on the lower side in the vertical direction faces downward in the vertical direction, that is, toward the fuel nozzle 51, so that the secondary air approaches the fuel gas. Each of the divided openings 103 ejected toward the upper side in the vertical direction faces upward in the vertical direction, that is, the side away from the fuel nozzle 51, and in the direction away from the fuel gas. It spouts towards. Further, in the ejection opening 101Bb, each divided opening 104 disposed on the upper side in the vertical direction faces the upper side in the vertical direction, that is, the fuel nozzle 51 side, so that the secondary air approaches the fuel gas. Each of the divided openings 105 that are ejected toward the lower side in the vertical direction faces the lower side in the vertical direction, that is, the side away from the fuel nozzle 51, and in the direction in which the secondary air is separated from the fuel gas. It spouts towards.

  Each of the divided openings 102 and 104 is configured to jet the secondary air toward the fuel nozzle 51 in a direction approaching the fuel gas, but the secondary air is parallel to the jet direction of the fuel gas. You may comprise so that it may eject.

  In addition, although the divided openings 102, 103, 104, 105 are rectangular in the ejection openings 101Ab, 101Bb, they may be squares, polygons, circles, ellipses, or the like. Further, the number of the divided openings 102, 103, 104, 105 is not limited to that described above, and may be set as appropriate. Furthermore, although the plurality of divided openings 102, 103, 104, 105 are arranged in the horizontal direction, they may be connected directly or by connecting openings, or may be separated in the horizontal direction. Further, the divided openings 102, 103, 104, 105 may be arranged so as to overlap in the horizontal direction.

  Therefore, the fuel gas is ejected from the fuel nozzle 51 into the furnace, the fuel gas combustion air is ejected from the combustion air nozzle 52 to the outside of the fuel gas, that is, around the fuel gas, and the secondary air is 2 The secondary air nozzles 101A and 101B are ejected to the outside of the fuel gas combustion air. At this time, in the secondary air nozzles 101A and 101B, the ejection openings 101Ab and 101Bb have shapes different from the passage cross-sectional shapes of the air passages 101Aa and 101Ba. Therefore, when the secondary air flowing through the air passages 101Aa and 101Ba is ejected into the furnace through the ejection openings 101Ab and 101Bb, the secondary air at the ejection openings 91Ab and 91Bb is close to a square, so that the penetration force is improved. That is, since the ejection openings 101Ab and 101Bb are composed of a plurality of divided openings 102, 103, 104, and 105 that are shifted in the vertical direction, the secondary air jet becomes strong, and the secondary air jet is properly maintained. As a result, mixing with the fuel gas is ensured.

  The secondary air ejected from the outer peripheral side of the combustion burner 21 is easily affected by the flow of the flame swirl flow C (see FIG. 6) from the horizontal direction. However, in the present embodiment, due to the shape of the secondary air nozzles 101A and 101B, the secondary air is ejected in the direction in which the divided openings 102 and 104 approach the fuel gas, and the divided openings 103 and 105 are fuel gas. Secondary air is ejected in a direction away from the air. For this reason, the secondary air ejected from each of the divided openings 102 and 104 is mixed with the fuel gas and burned, thereby suppressing the generation of unburned fuel. On the other hand, the secondary air ejected from each of the divided openings 103 and 105 moves away from the fuel gas, thereby suppressing excess air and suppressing the generation of NOx. Then, the secondary air ejected from the secondary air nozzles 101A and 101B flows to an appropriate vertical position with respect to the fuel gas ejected from the fuel nozzle 51, and the combustion is stabilized.

  As described above, in the combustion burner of the third embodiment, the divided openings 102, 103, 104, 105 of the secondary air nozzles 101A, 101B are shifted in the vertical direction.

  Therefore, by supplying the secondary air jets from the secondary air nozzles 101A and 101B to the appropriate positions, it is possible to suppress the generation of unburned fuel, and to suppress the excess air and reduce the generation of NOx. Can be suppressed.

  In the combustion burner of the third embodiment, the secondary air from each of the divided openings 102 and 104 is ejected in a direction approaching the fuel gas, and the secondary air from each of the divided openings 103 and 105 is separated from the fuel gas. Spouts in the direction. Therefore, generation | occurrence | production of the unburned part in fuel and generation | occurrence | production of NOx by excess air can be suppressed further.

  In the above-described embodiment, the boiler of the present invention is a coal-fired boiler, but the solid fuel may be a boiler using biomass, petroleum coke, petroleum residue, or the like in addition to coal. Further, the fuel is not limited to a solid fuel, and can be used for an oil-fired boiler such as heavy oil. Furthermore, the present invention can be applied to mixed combustion of these fuels.

10 Boiler 11 Furnace 12 Combustion device 13 Flue 21, 22, 23, 24, 25 Combustion burner 26, 27, 28, 29, 30 Pulverized fuel supply pipe 31, 32, 33, 34, 35 Crusher 36 Wind box 39 Addition Air nozzle 41, 42, 43 Superheater (heat exchanger)
44, 45 Reheater (heat exchanger)
46, 47 economizer (heat exchanger)
51 Fuel nozzle 52 Combustion air nozzle 53, 53A, 53B, 91, 91A, 91B, 101, 101A, 101B Secondary air nozzle 53Aa, 53Ba, 101Aa, 101Ba Air passage 53Ab, 53Bb, 91Ab, 91Bb, 101Ab, 101Bb Opening 54 Flame holder 61, 62, 63, 64 Flame holding member 81, 83, 102, 103, 104, 105 Divided opening 82, 84 Connection opening 92, 94 First opening 93, 95 Second opening

Claims (11)

A fuel nozzle that jets fuel gas mixed with fuel and air along a horizontal direction;
A secondary air nozzle that ejects air along a horizontal direction on an upper side and a lower side in the vertical direction of the fuel nozzle;
With
The secondary air nozzle has an air passage and an ejection opening provided on the downstream side of the air passage in the air flow direction,
The ejection opening has a shape in which an opening area in a vertical direction is different from a passage cross-sectional shape of the air passage.
Combustion burner characterized by that.   2. The combustion burner according to claim 1, wherein the ejection opening has a plurality of divided openings provided at predetermined intervals along a horizontal direction intersecting an air ejection direction.   The combustion burner according to claim 2, wherein the plurality of divided openings are connected to each other by a connecting opening having a smaller opening area in the vertical direction than the divided openings.   The combustion burner according to claim 3, wherein the plurality of divided openings are arranged so as to be shifted in the vertical direction.   The divided opening disposed away from the fuel nozzle ejects air in a direction away from the fuel nozzle, and the divided opening disposed close to the fuel nozzle approaches air toward the fuel nozzle. The combustion burner according to claim 4, wherein the combustion burner is ejected in a direction in which the fuel is burned.   The ejection opening is provided on one side in the horizontal direction intersecting the air ejection direction, and on the other side in the horizontal direction intersecting the air ejection direction, and is more vertically open than the first opening. The combustion burner according to claim 1, further comprising a second opening having a large area.   2. The combustion burner according to claim 1, wherein the ejection opening is arranged so as to be shifted to one side in a horizontal direction intersecting an air ejection direction.   The ejection opening has a first opening arranged on one side in the horizontal direction and having a large opening area in the vertical direction, and a second opening arranged on the other side in the horizontal direction and having a small opening area in the vertical direction. 8. A combustion burner according to claim 7, characterized in that   The combustion burner according to any one of claims 1 to 8, wherein a flame holder is provided at a tip portion of the fuel nozzle. A plurality of combustion burners according to any one of claims 1 to 9 are arranged at predetermined intervals in the circumferential direction to form a flame swirl flow.
Combustion device characterized by that. A furnace that is hollow and installed along the vertical direction;
A combustion apparatus according to claim 10;
A boiler characterized by comprising.

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