JP2016118329A - Combustion burner and boiler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress corrosion of a furnace wall and further to suppress attachment of molten ash to the furnace wall with a simple constitution.SOLUTION: A combustion burner in which a fuel gas obtained by mixing a solid fuel and air is jetted into a furnace from a jetting port, includes: a fuel supply pipe disposed along a vertical direction and having a curved portion for curving a fuel gas flow in a horizontal direction; an upstream side plate disposed at a downstream side in the fuel gas flowing direction with respect to the curved portion and dividing a flow channel of a fuel supply pipe into two of an upper part and a lower part; and a downstream side plate disposed at a downstream side in the fuel gas flowing direction with respect to the upstream side plate, and dividing the flow channel into two of a furnace wall side close to a wall of the furnace and a furnace inner side close to the inside of the furnace. When the flow channel is observed from the jetting port, a cross-sectional area orthogonal to the fuel gas flowing direction of the flow channel is divided into four by a downstream end portion of the upstream side plate and an upstream end portion of the downstream side plate, and a ratio of a cross-sectional area of an upper and furnace wall side to the sum of the cross-sectional areas of the upper and lower furnace wall sides, is smaller than a ratio of a cross-sectional area of an upper and furnace inner side to the sum of the cross-sectional area of the upper and lower furnace inner sides.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a pulverized fuel combustion burner and a pulverized fuel burning boiler.

  A conventional coal-fired boiler has a furnace that has a hollow shape and is installed in a vertical direction, and a plurality of combustion burners are arranged on the furnace wall along the circumferential direction of the furnace. It is arranged over the steps. The combustion burner is supplied with pulverized coal obtained by pulverizing coal, that is, fuel gas that is a mixture of fuel and primary air that is carrier air, and is also supplied with high-temperature secondary air. Gas and secondary air are blown into the furnace to form a flame that can be combusted in the furnace. This furnace has a flue connected to the top, and this flue is provided with a superheater, reheater, economizer, etc. for recovering the heat of exhaust gas, and it was generated by combustion in the furnace. Heat exchange is performed between the exhaust gas and water, and steam can be generated.

  In such a coal fired boiler, in-furnace denitration technology is generally employed. That is, a plurality of combustion burners are provided on the furnace wall, and an additional air nozzle is provided above the combustion burner to perform two-stage combustion. Therefore, the combustion burner blows fuel gas into the furnace and blows secondary air as combustion air into the furnace and ignites it to form a flame. The additional combustion air nozzle blows additional combustion air into the furnace to perform combustion control. At this time, in the furnace, the supply amount of the secondary air is set so as to be less than the theoretical air amount with respect to the supply amount of the pulverized coal, so that the inside is maintained in a reducing atmosphere and is generated by the combustion of the pulverized coal. NOx is reduced, and then additional combustion air is additionally supplied to complete the oxidative combustion of the pulverized coal, and the amount of NOx generated by the combustion of the pulverized coal is reduced.

In such a furnace, in a region in a combustion atmosphere or a reducing atmosphere, it becomes a low oxygen region and a high temperature region, so that hydrogen sulfide (H ₂ S), which is a corrosive component, is likely to be generated. Corrosion may occur on the inner surface. In addition, adhesion of molten ash to the furnace wall or too little adhesion of molten ash to the furnace wall may cause heat transfer / combustion failure.

  Therefore, conventionally, by adjusting the direction of the burner body adjacent to the furnace wall or the fuel injection direction of the burner fuel nozzle so that the flame does not directly hit the furnace wall, the sulfur-containing fuel that prevents corrosion of the furnace wall is prevented. A combustion apparatus is known (for example, Patent Document 1). In addition, a twist plate is provided in the pulverized fuel pipe, and the pulverized fuel is biased toward the inside of the furnace, or by increasing the amount of air close to the furnace wall, the fine pulverized form prevents molten ash from adhering to the furnace wall. A fuel combustion burner is known (for example, Patent Document 2). Alternatively, the pulverized coal mixture nozzle is provided with a pulverized coal concentration distribution adjusting block and a pulverized coal mixture flux rotating plate on the downstream side thereof, and the distribution of the pulverized coal in the nozzle cross section is changed. There is known a pulverized coal burner that can control the place or amount of adhesion (for example, Patent Document 3).

Japanese Patent Laid-Open No. 11-22915 JP-A-10-274403 JP 2005-156015 A

  However, as in Patent Document 1, adjusting the orientation of the burner body or adjusting the fuel injection direction of the burner fuel nozzle may complicate the structure of the burner and increase the manufacturing cost. There is sex. Further, as in Patent Document 2 or Patent Document 3, a twist plate is provided in the pipe for supplying the fuel gas so as to prevent the molten ash from adhering to the furnace wall or to control the position or amount of the molten ash adhered. It is necessary to construct a plate having a twist three-dimensionally on the pipe by providing a rotating plate with a flow velocity. Therefore, the structure of the burner becomes complicated, construction becomes difficult, and the manufacturing cost may increase.

  The present invention has been made in view of the above, and a combustion burner and a boiler which improve durability by suppressing corrosion of the furnace wall with a simple configuration and suppressing adhesion of molten ash to the furnace wall. The purpose is to provide.

  In order to solve the above problems, a combustion burner according to one aspect of the present invention is a combustion burner that jets fuel gas, which is a mixture of solid fuel and air, into a furnace from a jet outlet, and is installed along a vertical direction. And a fuel supply pipe having a curved portion that bends the flow of the fuel gas in the horizontal direction, and is located downstream of the curved portion in the flow direction of the fuel gas, and flows upward and downward from the fuel supply pipe. An upstream plate that bisects the path; and the downstream side of the upstream side plate in the flow direction of the fuel gas, the flow to the furnace wall side closer to the furnace wall and to the furnace inner side closer to the furnace interior A cross section perpendicular to the flow direction of the fuel gas in the flow path when the flow path is viewed from the injection port, the downstream end of the upstream plate and the downstream plate The upper and lower furnace walls are divided by the upstream end of the side plate. The ratio of the cross-sectional area of the upper and furnace wall to the sum of the cross-sectional area of the may be smaller than the ratio of the cross-sectional area of the upper and furnace interior to the sum of the cross-sectional area of the furnace interior of the upper and lower.

  According to such a configuration, durability can be improved by suppressing corrosion of the furnace wall with a simple configuration and suppressing adhesion of molten ash to the furnace wall.

  Further, in the combustion burner according to another aspect of the present invention, the cross section perpendicular to the flow direction of the fuel gas in the flow path is provided with a circular portion or a curved portion at four corners at a position including the upstream end portion of the downstream side plate. It is a rectangle or a rectangle provided with curved portions at four corners at a position including the jet port, and an upstream end portion of the upstream plate is located below a downstream end portion of the upstream plate, The downstream end of the upstream plate is located above the central axis of the flow path, and the upstream end of the downstream plate is located on the road wall side of the central axis of the flow path.

  According to such a configuration, the cross section perpendicular to the flow direction of the fuel gas in the flow path is a circle or a rectangle provided with curved portions at the four corners at a position including the upstream end portion of the downstream side plate, In the case of a rectangular or rectangular fuel supply pipe with curved portions at the four corners at the included position, durability is improved by suppressing corrosion of the furnace wall with a simple configuration and suppressing adhesion of molten ash to the furnace wall Can be achieved.

  In the combustion burner according to another aspect of the present invention, the cross section of the flow path perpendicular to the flow direction of the fuel gas may include the fuel supply pipe from the downstream end of the curved portion to the jet outlet. The upstream end of the upstream side plate is located below the downstream end of the upstream side plate, and the downstream end of the upstream side plate is located above the central axis of the flow path. The upstream end of the downstream plate is located on the road wall side with respect to the central axis of the flow path.

  According to such a configuration, the fuel supply pipe whose cross section perpendicular to the flow direction of the fuel gas in the flow path is circular at any position including the fuel supply pipe from the downstream end portion of the curved portion to the jet port. In this case, it is possible to improve durability by suppressing corrosion of the furnace wall with a simple configuration and suppressing adhesion of molten ash to the furnace wall.

  Moreover, the combustion burner which concerns on the other aspect of this invention is equipped with the density separator provided inside the said fuel supply pipe | tube immediately before the said curved part.

  According to such a configuration, durability can be improved by suppressing corrosion of the furnace wall with a simple configuration and suppressing adhesion of molten ash to the furnace wall. Further, the flow path can be more reliably divided into a region where the fine fuel concentration is high and a region where the fine fuel concentration is low by the density separator.

  The combustion burner according to another aspect of the present invention is characterized in that the upstream side plate is a curved plate convex upward along the flow direction of the fuel gas.

  According to such a configuration, durability can be improved by suppressing corrosion of the furnace wall with a simple configuration and suppressing adhesion of molten ash to the furnace wall. Further, since the upstream side plate is a curved plate that protrudes upward along the fuel gas flow direction, the upstream side plate suppresses the separation of the fuel gas, and the upper pulverized fuel concentration region and the lower pulverized fuel The flow path can be divided into a region having a low concentration.

  Further, the combustion burner according to another aspect of the present invention is characterized in that the downstream end portion of the downstream side plate is positioned inside the furnace than the upstream end portion of the downstream side plate.

  According to such a configuration, durability can be improved by suppressing corrosion of the furnace wall with a simple configuration and suppressing adhesion of molten ash to the furnace wall. Further, the downstream side plate can bias the flow of the fuel gas having a high pulverized fuel concentration toward the inside of the furnace.

  Moreover, the combustion burner according to another aspect of the present invention is characterized in that the downstream side plate is a curved plate convex toward the furnace wall along the flow direction of the fuel gas.

  According to such a configuration, durability can be improved by suppressing corrosion of the furnace wall with a simple configuration and suppressing adhesion of molten ash to the furnace wall. Further, since the downstream side plate is a curved plate convex toward the furnace wall along the flow direction of the fuel gas, the downstream side plate suppresses the separation of the fuel gas and suppresses the flow of the fuel gas having a high pulverized fuel concentration. Can be biased inward.

  Moreover, the combustion burner according to another aspect of the present invention is characterized in that the downstream end portion of the downstream side plate is a deflecting portion that deflects toward the furnace in the middle of the flow direction of the fuel gas.

  According to such a configuration, durability can be improved by suppressing corrosion of the furnace wall with a simple configuration and suppressing adhesion of molten ash to the furnace wall. Further, the flow of the fuel gas having a high pulverized fuel concentration can be biased to the inside of the furnace by the deflecting unit.

  In addition, a combustion burner according to another aspect of the present invention includes a first deflector plate located downstream of the downstream plate, and an upstream end portion of the first deflector plate is a downstream end of the downstream plate. The downstream end portion of the downstream side plate is in contact with the portion, and is located on the inner side of the furnace than the downstream end portion of the first deflection plate.

  According to such a configuration, durability can be improved by suppressing corrosion of the furnace wall with a simple configuration and suppressing adhesion of molten ash to the furnace wall. Further, the flow of the fuel gas having a high pulverized fuel concentration can be biased to the inside of the furnace by the first deflecting plate.

  In addition, a combustion burner according to another aspect of the present invention includes a second deflection plate provided on the furnace wall side inside the fuel supply pipe in the vicinity of the jet port, and the fuel gas generated by the first deflection plate is provided. Along with the deflection toward the furnace inner side, the downstream end portion of the second deflection plate is located closer to the furnace inner side than the upstream end portion of the second deflection plate.

  According to such a configuration, durability can be improved by suppressing corrosion of the furnace wall with a simple configuration and suppressing adhesion of molten ash to the furnace wall. Further, the flow of the fuel gas having a high pulverized fuel concentration can be biased to the inside of the furnace by the first deflector, and the flow of the fuel gas having a low pulverized fuel concentration can also be biased to the inside of the furnace by the second deflector. The flame can be further away from the furnace wall.

  The combustion burner according to another aspect of the present invention is characterized in that a downstream end portion of the downstream side plate is located at the ejection port.

  According to such a configuration, durability can be improved by suppressing corrosion of the furnace wall with a simple configuration and suppressing adhesion of molten ash to the furnace wall. In addition, since the downstream end of the downstream side plate is positioned at the jet outlet, the flow path can be more reliably divided into a high-fine fuel concentration area and a low-area until the fuel gas is just jetted from the jet outlet. .

  Moreover, the boiler which concerns on 1 aspect of this invention makes the hollow furnace and is installed along a perpendicular direction, at least 1 combustion burner which concerns on 1 aspect of this invention, and the said combustion burner. And an additional air nozzle for blowing additional air into the furnace.

  According to such a configuration, durability can be improved by suppressing corrosion of the furnace wall with a simple configuration and suppressing adhesion of molten ash to the furnace wall.

  According to the combustion burner of the present invention and the boiler including the combustion burner, durability can be improved by suppressing corrosion of the furnace wall with a simple configuration and suppressing adhesion of molten ash to the furnace wall.

FIG. 1 is a schematic configuration diagram showing a pulverized fuel-fired boiler having a combustion burner. FIG. 2 is a plan view showing a combustion burner in a pulverized fuel-fired boiler. FIG. 3 is a schematic configuration diagram of the combustion burner according to the first embodiment of the present invention. FIG. 4 is a cross-sectional view of the fuel supply pipe according to the first embodiment of the present invention (A-A portion shown in FIG. 3). FIG. 5 is a cross-sectional view (BB portion shown in FIG. 3) of the fuel supply pipe according to the first embodiment of the present invention. FIG. 6 is a cross-sectional view (CC section shown in FIG. 3) of the fuel supply pipe according to the first embodiment of the present invention. FIG. 7 is a front view of the fuel supply pipe according to the first embodiment of the present invention. FIG. 8 is a cross-sectional view showing the arrangement of the upstream side plate in the fuel supply pipe according to the first embodiment of the present invention. FIG. 9 is a cross-sectional view showing the arrangement of the downstream side plate in the fuel supply pipe according to the first embodiment of the present invention. FIG. 10 is a plan view showing a combustion region in the pulverized fuel burning boiler having the combustion combustion burner according to the first embodiment of the present invention. FIG. 11 is a cross-sectional view (DD section shown in FIG. 3) of the fuel supply pipe including a first modification of the upstream plate according to the first embodiment of the present invention. FIG. 12 is a cross-sectional view of the fuel supply pipe (E-E portion shown in FIG. 3) including a first modification of the downstream side plate according to the first embodiment of the present invention. FIG. 13 is a cross-sectional view of the fuel supply pipe (the EE portion shown in FIG. 3) including a second modification of the downstream side plate according to the first embodiment of the present invention. FIG. 14 is a cross-sectional view (E-E portion shown in FIG. 3) of the fuel supply pipe including a third modification of the downstream side plate according to the first embodiment of the present invention. FIG. 15 is a cross-sectional view of the fuel supply pipe including the first deflecting plate according to the first embodiment of the present invention (EE section shown in FIG. 3). FIG. 16 is a cross-sectional view of the fuel supply pipe including the second deflecting plate according to the first embodiment of the present invention (EE section shown in FIG. 3).

  A mode for carrying out the present invention (hereinafter referred to as an embodiment) will be described in detail with reference to the drawings. It should be noted that the present invention is not limited to the embodiments described below, and when there are a plurality of embodiments, those configured by combining the embodiments are also included in the present invention. In this embodiment, the downward direction is the vertical direction, that is, the direction of gravity, and the upward direction is the direction opposite to the vertical direction, that is, the direction opposite to the direction of gravity.

(First embodiment)
FIG. 1 is a schematic configuration diagram illustrating a pulverized fuel-fired boiler. The pulverized fuel-fired boiler can pulverize the pulverized fuel with a combustion burner and recover heat generated by the combustion. As shown in FIG. 1, the pulverized fuel-fired boiler is a coal-fired boiler 10 that uses pulverized coal obtained by pulverizing coal such as bituminous coal and sub-bituminous coal as pulverized fuel. In the first embodiment, the coal-fired boiler 10 and the combustion burners 21, 22, 23, 24, and 25 are used. However, as the pulverized fuel, biomass, petroleum coke, or the like may be used in addition to the pulverized coal.

  The coal fired boiler 10 includes a furnace 11 and a combustion device 13. The furnace 11 is installed along the vertical direction with a hollow shape of a rectangular tube, and the furnace walls 11a, 11b, 11c, and 11d constituting the furnace 11 are constituted by heat transfer tubes.

  The combustion apparatus 13 is provided in the lower part of the furnace wall which comprises this furnace 11. FIG. This combustion apparatus 13 has a plurality of combustion burners 21, 22, 23, 24, 25 mounted on furnace walls 11a, 11b, 11c, 11d. And the combustion apparatus 13 makes 5 sets along the vertical direction, ie, 5 steps | paragraphs by making one set into which the four combustion burners were arrange | positioned along the circumferential direction of the furnace 11 at equal intervals. . The combustion burners 21, 22, 23, 24, and 25 are a CCF (Circular Corner Filling) combustion system, and the shape of the furnace 11, the number of combustion burners in one stage, and the number of stages are limited to this configuration. is not. In the first embodiment, the form of the combustion burner is the CCF combustion method, but it may be a CUF (Circular Ultra Fire) combustion method.

  Each combustion burner 21, 22, 23, 24, 25 is connected to a pulverized coal machine 31, 32, 33, 34, 35 such as a mill via fuel supply pipes 26, 27, 28, 29, 30. Although not shown, the pulverized coal machines 31, 32, 33, 34, and 35 are supported in a housing so that the pulverization table can be driven to rotate with a rotation axis along the vertical direction, and face the upper side of the pulverization table. A plurality of crushing rollers are rotatably supported in conjunction with rotation of the crushing table. Therefore, when coal is introduced between a plurality of crushing rollers and a crushing table, it is crushed to a predetermined size. The pulverized coal is classified by primary air that is air for conveyance. The classified pulverized coal is supplied to the combustion burners 21, 22, 23, 24, and 25 from the fuel supply pipes 26, 27, 28, 29, and 30 together with the primary air.

  In the furnace 11, a wind box 36 is provided at the mounting position of each combustion burner 21, 22, 23, 24, 25. One end of an air duct 37 is connected to the wind box 36. The air duct 37 has a blower 38 attached to the other end. Therefore, the combustion air sent by the blower 38 can be supplied from the air duct 37 to the wind box 36 and supplied from the wind box 36 to the combustion burners 21, 22, 23, 24, 25.

  Here, the combustion device 13 will be described in detail. FIG. 2 is a plan view showing a combustion region in the pulverized fuel-fired boiler. Since the combustion burners 21, 22, 23, 24, and 25 constituting the combustion device 13 have substantially the same configuration, only the combustion burner 21 located at the uppermost stage will be described.

  As shown in FIG. 2, the combustion burner 21 includes combustion burners 21a, 21b, 21c, and 21d provided at four corners 12a, 12b, 12c, and 12d in the furnace 11. Each combustion burner 21a, 21b, 21c, 21d is connected to each branch pipe 26a, 26b, 26c, 26d branched from the fuel supply pipe 26, and each branch pipe 37a, 37b, 37c, branched from the air duct 37. 37d is connected.

  Therefore, each combustion burner 21a, 21b, 21c, 21d at each corner of the furnace 11 is blown into the furnace 11 with fuel gas mixed with pulverized coal and primary air, and outside the fuel gas. Blow in secondary air. By igniting the fuel gas from each combustion burner 21a, 21b, 21c, 21d, four flames F1, F2, F3, F4 can be formed. As shown in FIG. 2, the flames F1, F2, F3, and F4 become a flame swirl flow that swirls counterclockwise as viewed from above the furnace 11. That is, in the flames F1, F2, F3, and F4, the fuel gas is injected from the combustion burners 21a, 21b, 21c, and 21d at positions that are biased toward the furnace walls 11a, 11b, 11c, and 11d from the center of the furnace 11, respectively. Is formed. At this time, the central axis of the fuel gas flow direction GF is biased toward the furnace walls 11 a, 11 b, 11 c, 11 d of the furnace 11. The furnace wall 11a, 11b, 11c, 11d side of the furnace 11 is the furnace wall side, and the inside side of the furnace 11 that is the opposite side is the furnace inner side. The turning direction of the flames F1, F2, F3, and F4 is not limited to the counterclockwise direction when viewed from above the furnace 11, and may be the clockwise direction.

  As shown in FIG. 1, the furnace 11 is provided with an additional combustion air supply device 41 at the upper stage of the combustion device 13. The additional combustion air supply device 41 has a plurality of additional combustion air nozzles 42 and 43 attached to the furnace walls 11a, 11b, 11c and 11d. The additional combustion air nozzles 42 and 43 are arranged in a set of four at equal intervals along the circumferential direction of the furnace 11, and two sets along the vertical direction, that is, two stages are arranged. Yes. That is, the additional combustion air nozzles 42 and 43 are disposed above the mounting position of the combustion burner 21 in the furnace 11. The additional combustion air supply device 41 blows in additional combustion air (Over Fire Air) into the furnace 11. That is, the additional combustion air nozzles 42 and 43 are provided with a plurality of additional combustion airs provided at the four corners 12a, 12b, 12c and 12d in the furnace 11 in the same manner as the combustion burners 21, 22, 23, 24 and 25. It consists of nozzles and forms an additional combustion air swirl similar to the flame swirl. The flow rate of the additional combustion air is adjusted in the additional air nozzles 42 and 43 by a damper of the wind box.

  Each additional combustion air nozzle 42, 43 can blow additional combustion air above the fuel gas blown by the combustion burners 21, 22, 23, 24, 25.

  The furnace 11 is provided with an additional air supply device 51 above the combustion device 13. The additional air supply device 51 has a plurality of additional air nozzles 52 attached to the furnace walls 11a, 11b, 11c, and 11d. One set of the additional air nozzles 52 arranged at equal intervals along the circumferential direction of the furnace 11, that is, one stage is arranged. That is, the additional air nozzle 52 is disposed above the mounting position of the combustion burner 21 in the furnace 11 by a predetermined distance. The additional air supply device 51 blows additional air (Additional Air) into the furnace 11. That is, the additional air nozzle 52 is composed of a plurality of additional air nozzles provided at the four corners 12a, 12b, 12c, and 12d in the furnace 11, like the combustion burners 21, 22, 23, 24, and 25. An additional air swirl similar to the flame swirl is formed. The additional air nozzle 52 is connected to the end of a branch air duct 53 branched from the air duct 37.

  Therefore, the combustion air sent by the blower 38 can be supplied from the branch air duct 53 to the additional air supply device 51. The additional air nozzle 52 blows additional air upward by a predetermined distance between the fuel gas blown by the combustion burners 21, 22, 23, 24, and 25 and the additional combustion air blown by the additional combustion air nozzles 42 and 43. be able to.

  In addition, although not shown in figure, each combustion burner 21,22,23,24,25 which comprises the combustion apparatus 13 of this embodiment is an oil nozzle which can inject oil fuel between upper and lower burners, and the outer side of this oil nozzle A fuel nozzle capable of injecting fuel gas, and a secondary air nozzle capable of injecting secondary air outside the fuel nozzle. Therefore, when the boiler is started, each combustion burner 21, 22, 23, 24, 25 injects oil fuel into the furnace 11 to form a flame, and then injects fuel gas and secondary air into the furnace 11. Thus, the flames F1, F2, F3, and F4 shown in FIG. 2 are formed.

  As shown in FIG. 1, a furnace 11 has a flue 70 connected to an upper portion thereof, and superheaters 71 and 72 for recovering the heat of combustion gas as a convection heat transfer section and reheat to the flue 70. Units 73 and 74 and economizers 75, 76, and 77 are provided. The convection heat transfer section exchanges heat between the exhaust gas generated by the combustion in the furnace 11 and water.

  The flue 70 is connected to an exhaust gas pipe 78 from which exhaust gas subjected to heat exchange is discharged downstream. The exhaust pipe 78 is provided with an air heater 79 between the air duct 37, and performs heat exchange between the combustion air flowing through the air duct 37 and the exhaust gas flowing through the exhaust pipe 78, and the combustion burners 21, 22, 22. The temperature of the combustion air supplied to 23, 24, 25 can be increased.

  And although the exhaust gas pipe 78 is not shown in figure, a denitration apparatus, an electrostatic precipitator, an induction blower, and a desulfurization apparatus are provided, and the chimney is provided in the downstream end part.

  When the pulverized coal machines 31, 32, 33, 34, and 35 are driven, the coal-fired boiler 10 configured in this way has the fuel supply pipes 26, 27, 28, 29, 30 are supplied to the combustion burners 21, 22, 23, 24, 25. Further, secondary air that is heated combustion air is supplied from the air duct 37 to the combustion burners 21, 22, 23, 24, and 25 via the wind box 36. The heated combustion air is supplied to the additional combustion air nozzle 43 and the additional air nozzle 52 by the branch air duct 53 branched from the air duct 37.

  Then, the combustion burners 21, 22, 23, 24, and 25 are ignited by the fuel gas and the secondary air mixed with the pulverized coal and the primary air being blown into the furnace 11 to be ignited. A flame swirl can be formed in A. At this time, the additional combustion air nozzles 42 and 43 can appropriately form the combustion region A by blowing the additional combustion air into the furnace 11. In the furnace 11, the fuel gas, the secondary air, and the additional combustion air are burned to generate a flame swirl flow. When a flame swirl is generated in the combustion region A, the combustion gas rises while swirling in the furnace 11 and reaches the reduction region B.

  At this time, the combustion burners 21, 22, 23, 24, and 25 included in the furnace 11 are set so that the supply amount of air is less than the theoretical air amount with respect to the supply amount of pulverized coal. The reduction region B above is maintained in a reducing atmosphere. Therefore, NOx generated by the combustion of pulverized coal is reduced in this reduction region B.

  The additional air nozzle 52 blows additional air above the reduction region B of the furnace 11. Then, in the combustion completion region C, the combustion gas and the additional air react to complete oxidation combustion of the pulverized coal, and the amount of NOx generated by the combustion of the pulverized coal is reduced.

Incidentally, in the combustion region A and the reduction region B, the oxygen concentration is low due to air shortage, and the distance between the flame and the furnace wall is close and high, so a low oxygen and high temperature region is formed. Therefore, hydrogen sulfide (H ₂ S), which is a corrosive component, is likely to be generated, and corrosion may occur on the inner surface of the furnace wall. Further, in the combustion region A and the reduction region B, fly ash melts in the vicinity of the furnace wall, and molten ash adheres to the furnace wall, which may cause heat transfer and combustion failure.

  Next, the combustion burner 21 according to the first embodiment will be described in more detail. In addition, each combustion burner 21a, 21b, 21c, 21d in each corner | angular part 12a, 12b, 12c, 12d of the furnace 11 is the same structure only in arrangement positions differing. Hereinafter, when the point not related to the arrangement is described, the combustion burner 21 will be described.

  FIG. 3 is a schematic configuration diagram of the combustion burner according to the first embodiment of the present invention. 4 to 7 are a cross-sectional view and a front view of the fuel supply pipe according to the first embodiment of the present invention. FIG. 8 is a cross-sectional view showing the arrangement of the upstream side plate in the fuel supply pipe according to the first embodiment of the present invention. FIG. 9 is a cross-sectional view showing the arrangement of the downstream side plate in the fuel supply pipe according to the first embodiment of the present invention. FIG. 10 is a plan view showing a combustion region in the pulverized fuel burning boiler having the combustion combustion burner according to the first embodiment of the present invention.

  As shown in FIG. 3, the combustion burner 21 according to the first embodiment includes a fuel supply pipe 26 installed along the vertical direction, a curved portion 82 that is a part of the fuel supply pipe 26, and a curved portion 82. Is located downstream of the fuel gas flow direction GF, and is located on the downstream side of the upstream side plate 83 in the fuel gas flow direction GF with respect to the upstream plate 83 disposed in the fuel supply pipe 26, and the fuel supply pipe 26, a downstream side plate 84 disposed in the inside.

  The fuel supply pipe 26 is installed along the vertical direction and has a curved portion 82 that bends the flow of the fuel gas in the horizontal direction. The bending portion 82 is bent approximately 90 degrees. The fuel supply pipe 26 has an outlet 81 at the downstream end in the fuel gas flow direction GF for blowing out fuel gas, which is a mixture of pulverized coal and primary air, into the furnace 11. In FIG. 3, the right side is a jet 81 that is an outlet to the furnace 11. Assuming that the horizontal axis X and the vertical axis Y are downstream of the curved portion 82 in the fuel gas flow direction GF, the central axis Z of the flow path GP of the fuel supply pipe 26 is the X axis and the Y axis. Pass the intersection with. That is, as shown in FIGS. 3 to 9, the X-axis positive direction is the inside of the furnace, the opposite X-axis negative direction is the furnace wall side, the Y-axis positive direction is upward, and the opposite Y-axis negative direction is downward. It is.

  The upstream plate 83 is disposed in the fuel supply pipe 26 and is located downstream of the curved portion 82 in the fuel gas flow direction GF. The upstream plate 83 bisects the flow path GP of the fuel supply pipe 26 into an upper part and a lower part. 4 to 6, the upstream side plate 83 is a horizontal plate that bisects the flow path GP of the fuel supply pipe 26 upward and downward, but is not limited to this configuration, and as shown in FIG. Alternatively, a plate inclined by a predetermined angle θ from the horizontal direction may be used. However, the angle θ indicating the inclination with respect to the horizontal direction is not less than −45 degrees or not more than 45 degrees.

  The downstream plate 84 is disposed in the fuel supply pipe 26 and is located downstream of the upstream plate 83 in the fuel gas flow direction GF. The downstream side plate 84 bisects the flow path GP of the fuel supply pipe 26 into a furnace wall side near the furnace walls 11 a, 11 b, 11 c, 11 d of the furnace 11 and a furnace inside near the inside of the furnace 11. 6 or 7, the downstream side plate 84 is a vertical plate that bisects the flow path GP of the fuel supply pipe 26 between the furnace wall side and the inside of the furnace, but is not limited to this configuration. As shown, a plate inclined by a predetermined angle φ from the vertical direction may be used. However, the angle φ indicating the inclination with respect to the vertical direction is not less than −45 degrees or not more than 45 degrees.

  When the flow path GP of the fuel supply pipe 26 is viewed from the injection port 81, the cross section perpendicular to the fuel gas flow direction GF of the flow path GP is the downstream end 83 b of the upstream plate 83 and the upstream end of the downstream plate 84. It is divided by 84a. The downstream end 83b of the upstream plate 83 and the upstream end 84a of the downstream plate 84 may be in contact with each other or may be separated from each other.

  In the combustion burner 21 according to the first embodiment, with respect to the cross section of the flow path GP divided by the downstream end portion 83b of the upstream plate 83 and the upstream end portion 84a of the downstream plate 84, the upper and lower furnace wall side breaks. The ratio of the cross-sectional area of the upper side and the furnace wall to the sum of the areas is smaller than the ratio of the cross-sectional area of the upper side and the inner side of the furnace to the sum of the cross-sectional areas of the upper and lower side of the furnace. That is, as shown in FIG. 6, when the cross-sectional area S1 on the upper side and the inner side of the furnace, the cross-sectional area S2 on the upper side and the furnace wall side, the cross-sectional area S3 on the lower side and the furnace wall side, The wall-side cross-sectional area ratio S2 / (S2 + S3) is smaller than the furnace-side cross-sectional area ratio S1 / (S1 + S4).

  The flow of the fuel gas in the vertical direction in the fuel supply pipe 26 exhibits a substantially uniform pulverized coal concentration distribution in front of the curved portion 82. Then, the flow of the fuel gas causes the pulverized coal particles to drift out of the curved portion, that is, above the curved portion due to the centrifugal force generated by the curved portion 82 being bent in the horizontal direction, and the pulverized coal concentration distribution is biased. Therefore, a region having a high upper pulverized coal concentration and a region having a lower pulverized coal concentration are generated in the flow path GP. However, in the conventional combustion burner, even if the pulverized coal concentration distribution is biased due to the drift in the curved portion 82, the bias is corrected before reaching the jet outlet 81, so the pulverized coal concentration distribution at the jet outlet is almost uniform. Met.

  On the other hand, as shown in FIG. 3 or FIG. 4, the combustion burner 21 according to the first embodiment is provided with the upstream plate 83 on the downstream side of the curved portion 82, so that the upstream plate 83 By utilizing the deviation of the pulverized coal concentration distribution caused by the uneven flow in the curved portion, the flow path GP is divided into two regions: the upper pulverized coal concentration region and the lower pulverized coal concentration region. Since the downstream side plate 84 is provided on the downstream side of the upstream side plate 83, the upstream end portion 84a of the downstream side plate 84 has an upper pulverized coal concentration region and a lower pulverized powder as shown in FIG. The flow path GP is divided into two parts, the region having a low charcoal concentration, and the furnace wall side and the furnace inner side, respectively. Thereafter, the fuel gas that has passed through the furnace wall side flow path GP or the furnace inner flow path GP separated by the downstream side plate 84 is jetted into the furnace 11 from the jet port 81. As described above, each of the combustion burners 21a, 21b, 21c, and 21d injects the combustion gas to positions that are biased toward the furnace walls 11a, 11b, 11c, and 11d with respect to the center portion of the furnace 11, respectively. F2, F3, and F4 are formed at positions that are biased toward the furnace wall side from the center of the furnace 11.

  At this time, considering the ratio of the cross-sectional area of the flow path GP, as shown in FIG. 6, the ratio S2 / (S2 + S3) of the cross-sectional area on the furnace wall side is larger than the ratio S1 / (S1 + S4) of the cross-sectional area inside the furnace. small. The upper region occupying the upper sectional area S1 and the upper sectional area S2 of the quartered flow path GP has the same pulverized coal concentration, and the pulverized coal concentration compared to the lower region. Is expensive. The lower region occupying the sectional area S3 on the lower and furnace wall side and the sectional area S4S4 on the lower and inner side of the divided flow path GP has the same concentration, and the pulverized coal concentration is lower than the upper region. . Therefore, since the ratio of the cross-sectional area on the furnace wall side is smaller than the ratio of the cross-sectional area on the furnace inner side, the pulverized coal concentration at the jet outlet 81 is smaller on the furnace wall side than on the furnace inner side. In other words, since the fuel gas ejected from the ejection port 81 has a smaller pulverized coal concentration on the furnace wall side than on the inside of the furnace, the flame contains more air on the furnace wall side than on the inside of the furnace.

  Therefore, as shown in FIG. 10, the high oxygen regions A1, A2, A3, A4 can be generated outside the flames F1, F2, F3, F4 approaching the furnace walls 11a, 11b, 11c, 11d. As a result, the vicinity of the furnace walls 11a, 11b, 11c, and 11d in the combustion region A and the reduction region B become the high oxygen regions A1, A2, A3, and A4, and the generation of hydrogen sulfide is suppressed. It is possible to suppress the occurrence of corrosion on the inner surfaces of the furnace walls 11a, 11b, 11c, and 11d. Further, the vicinity of the furnace walls 11a, 11b, 11c, and 11d in the combustion region A and the reduction region B becomes the high oxygen regions A1, A2, A3, and A4, so that the fly near the furnace walls 11a, 11b, 11c, and 11d. Since the ash can be prevented from melting and the molten ash can be prevented from adhering to the furnace walls 11a, 11b, 11c, and 11d, heat transfer and combustion failure can be suppressed.

  Further, in the conventional configuration in which a twist plate or a flow velocity rotating plate is provided in the fuel supply pipe in order to control the pulverized coal concentration distribution at the jet nozzle, the swirl is added to the flow of the fuel gas, so that the fear of ignition of the fuel gas is increased. Qualification may increase. On the other hand, since the combustion burner 21 according to the first embodiment of the present invention only provides two plates in the fuel supply pipe 26, the swirling of the flow of the fuel gas can be suppressed. Instability of ignition can be suppressed. In addition, the combustion burner 21 can easily apply two plates to the fuel supply pipe 26, compared to the conventional combustion burner configuration in which a plate having a twist needs to be applied three-dimensionally to the tube. Manufacturing cost can be reduced.

  Further, the combustion burner 21 is provided with curved portions 86 at round or four corners at a position where the cross section perpendicular to the fuel gas flow direction GF of the flow path GP of the fuel supply pipe 26 includes the upstream end portion 84a of the downstream side plate 84. A rectangular shape or a rectangular shape in which curved portions 86 are provided at four corners at a position including the ejection port 81 may be used. That is, as shown in FIGS. 4 to 7, the fuel supply pipe 26 is continuous with a rectangular pipe or a rectangular pipe provided with curved portions 86 at four corners from the circular pipe from the downstream end 82 b of the curved portion 82 to the jet outlet 81. 4 to 6, the upstream end 83a of the upstream plate 83 is positioned below the downstream end 83b of the upstream plate 83, and the downstream end of the upstream plate 83, as shown in FIGS. 83b is preferably located above the central axis Z of the flow path GP. Further, as shown in FIG. 6 or FIG. 7, the upstream end portion 84a of the downstream side plate 84 is preferably located on the road wall side with respect to the central axis Z of the flow path GP.

  Since the upstream end 83a of the upstream plate 83 is positioned below the downstream end 83b of the upstream plate 83, the upper cross section of the flow path GP divided into the upper side and the lower side by the upstream side plate 83 becomes downstream. The smaller the side. Thereby, the area | region where pulverized coal density | concentration is high is biased above the flow path GP toward the downstream side. The upstream end portion 84a of the downstream side plate 84 is located on the road wall side with respect to the central axis Z of the flow path GP, so that the ratio S2 / (S2 + S3) of the cross sectional area on the furnace wall side is equal to the cross sectional area on the inside of the furnace. It can be made smaller than the ratio S1 / (S1 + S4). Therefore, since the pulverized coal concentration at the jet outlet 81 can be smaller on the furnace wall side than on the furnace inner side, the high oxygen region is located outside the flames F1, F2, F3, and F4 approaching the furnace walls 11a, 11b, 11c, and 11d. A1, A2, A3, and A4 can be generated. As a result, the combustion burner 21 suppresses corrosion of the furnace walls 11a, 11b, 11c, and 11d, and improves durability by suppressing adhesion of molten ash to the furnace walls 11a, 11b, 11c, and 11d. be able to.

  Further, the combustion burner 21 has a cross section orthogonal to the flow direction of the fuel gas in the flow path GP of the fuel supply pipe 26 at any position including the fuel supply pipe 26 from the downstream end 82b of the curved portion 82 to the jet port 81. It may be circular. That is, although not shown, when the fuel supply pipe 26 is a circular pipe, the upstream end 83 a of the upstream plate 83 is located below the downstream end 83 b of the upstream plate 83, and the downstream end of the upstream plate 83. 83b is preferably positioned above the central axis Z of the flow path GP. In addition, the upstream end portion 84a of the downstream side plate 84 is preferably located on the road wall side with respect to the central axis Z of the flow path GP.

  Since the upstream end 83a of the upstream plate 83 is positioned below the downstream end 83b of the upstream plate 83, the upper cross section of the flow path GP divided into the upper side and the lower side by the upstream side plate 83 becomes downstream. The smaller the side. Thereby, the area | region where pulverized coal density | concentration is high is biased above the flow path GP toward the downstream side. The upstream end portion 84a of the downstream side plate 84 is located on the road wall side with respect to the central axis Z of the flow path GP, so that the ratio S2 / (S2 + S3) of the cross sectional area on the furnace wall side is equal to the cross sectional area on the inside of the furnace. It can be made smaller than the ratio S1 / (S1 + S4). Therefore, since the pulverized coal concentration at the jet outlet 81 can be made smaller on the furnace wall side than on the furnace inner side, the combustion burner 21 has the flames F1, F2, F3, F4 approaching the furnace walls 11a, 11b, 11c, 11d. High oxygen regions A1, A2, A3, A4 can be generated outside. As a result, the combustion burner 21 improves durability by suppressing corrosion of the furnace walls 11a, 11b, 11c, and 11d and suppressing adhesion of molten ash to the furnace walls 11a, 11b, 11c, and 11d. Can do.

  The combustion burner 21 may include a density separator 87 inside the fuel supply pipe 26 immediately before the curved portion 82. With such a configuration, as shown in FIG. 3, the fuel gas collides with the density separator 87, and the pulverized coal concentration on the opposite side to the density separator 87 becomes higher on the downstream side, and the downstream of the density separator 87. On the side, the pulverized coal concentration is low. That is, the pulverized coal concentration distribution can be biased downstream of the density separator 87. This deviation in the pulverized coal concentration distribution is further increased by the centrifugal force in the curved portion 82. Therefore, the upstream plate 83 and the downstream plate 84 on the downstream side of the density separator 87 make the flow path GP more surely between the region where the pulverized coal concentration inside the furnace is high and the region where the pulverized coal concentration is low on the furnace wall side. Can be divided. As a result, the combustion burner 21 generates high oxygen regions A1, A2, A3, A4 outside the flames F1, F2, F3, F4 approaching the furnace walls 11a, 11b, 11c, 11d, and the furnace walls 11a, 11b. , 11c, 11d and the adhesion of the molten ash to the furnace walls 11a, 11b, 11c, 11d can be suppressed and durability can be improved.

  Next, with reference to FIG. 11 to FIG. 16, the upstream side plate modification 101, the downstream side plate modifications 102 and 103, the deflection unit 104, the first deflection plate 105, and the second plate according to the first embodiment of the present invention. The deflection plate 106 will be described.

  FIG. 11 is a cross-sectional view (DD section shown in FIG. 3) of the fuel supply pipe including a first modification of the upstream plate according to the first embodiment of the present invention. The upstream side plate 101 shown in FIG. 11 is a curved plate convex upward along the fuel gas flow direction GF. With such a configuration, the flow path GP can be divided into a region where the upper pulverized coal concentration is high and a region where the lower pulverized coal concentration is low while suppressing separation of the fuel gas by the upstream side plate. As a result, the combustion burner 21 generates high oxygen regions A1, A2, A3, A4 outside the flames F1, F2, F3, F4 approaching the furnace walls 11a, 11b, 11c, 11d, and the furnace walls 11a, 11b. , 11c, 11d and the adhesion of the molten ash to the furnace walls 11a, 11b, 11c, 11d can be suppressed and durability can be improved.

  FIG. 12 is a cross-sectional view of the fuel supply pipe (E-E portion shown in FIG. 3) including a first modification of the downstream side plate according to the first embodiment of the present invention. In the downstream plate 102 shown in FIG. 12, the downstream end portion 102b is located inside the furnace with respect to the upstream end portion 102a. With such a configuration, the cross section inside the furnace including the downstream end portion 102b and orthogonal to the flow direction of the fuel gas in the flow path GP includes the upstream end portion 102a and the flow direction of the fuel gas in the flow path GP. Is smaller than the cross section inside the furnace. Thereby, the flow of the fuel gas having a high pulverized coal concentration in the vicinity of the jet port 81 can be biased further to the furnace inner side by the downstream side plate 102. As a result, the combustion burner 21 more reliably generates the high oxygen regions A1, A2, A3, and A4 outside the flames F1, F2, F3, and F4 approaching the furnace walls 11a, 11b, 11c, and 11d. It is possible to improve durability by suppressing corrosion of 11a, 11b, 11c, and 11d and suppressing adhesion of molten ash to the furnace walls 11a, 11b, 11c, and 11d.

  FIG. 13 is a cross-sectional view of the fuel supply pipe (the EE portion shown in FIG. 3) including a second modification of the downstream side plate according to the first embodiment of the present invention. The downstream side plate 103 shown in FIG. 13 is a curved plate that protrudes toward the furnace wall along the fuel gas flow direction GF. In the downstream side plate 103, the downstream end portion 103b is located on the inner side of the furnace than the upstream end portion 103a. With such a configuration, the cross section inside the furnace, including the downstream end portion 103b and orthogonal to the flow direction of the fuel gas in the flow path GP, includes the upstream end portion 103a and the flow direction of the fuel gas in the flow path GP. Is smaller than the cross section inside the furnace. At the same time, since the downstream side plate is a curved plate convex toward the furnace wall along the fuel gas flow direction GF, the downstream side plate 103 suppresses the separation of the fuel gas, and the pulverized coal near the outlet 81. The flow of the fuel gas having a high concentration can be more biased toward the inside of the furnace. As a result, the combustion burner 21 more reliably generates the high oxygen regions A1, A2, A3, and A4 outside the flames F1, F2, F3, and F4 approaching the furnace walls 11a, 11b, 11c, and 11d. It is possible to improve durability by suppressing corrosion of 11a, 11b, 11c, and 11d and suppressing adhesion of molten ash to the furnace walls 11a, 11b, 11c, and 11d.

  FIG. 14 is a cross-sectional view (E-E portion shown in FIG. 3) of the fuel supply pipe including a third modification of the downstream side plate according to the first embodiment of the present invention. The downstream side plate 104 in FIG. 14 has a deflecting portion 104b that deflects toward the inside of the furnace in the middle of the fuel gas flow direction GF. The deflection unit 104 b provided at the downstream end of the downstream side plate 104 is located inside the furnace with respect to the upstream end 104 a of the downstream side plate 104. With such a configuration, the cross section inside the furnace including the downstream end 104b and orthogonal to the flow direction of the fuel gas in the flow path GP includes the upstream end 104a and the flow direction of the fuel gas in the flow path GP. Is smaller than the cross section inside the furnace. Thereby, the flow of the fuel gas having a high pulverized fuel concentration in the vicinity of the jet nozzle 81 can be biased further to the furnace inner side by the deflecting unit 104b. As a result, the combustion burner 21 more reliably generates the high oxygen regions A1, A2, A3, and A4 outside the flames F1, F2, F3, and F4 approaching the furnace walls 11a, 11b, 11c, and 11d. It is possible to improve durability by suppressing corrosion of 11a, 11b, 11c, and 11d and suppressing adhesion of molten ash to the furnace walls 11a, 11b, 11c, and 11d.

  FIG. 15 is a cross-sectional view of the fuel supply pipe including the first deflecting plate according to the first embodiment of the present invention (EE section shown in FIG. 3). As shown in FIG. 15, the first deflection plate 105 is provided on the downstream side of the downstream side plate 84, and the upstream end portion 105 a of the first deflection plate 105 is in contact with the downstream end portion 84 b of the downstream side plate 84, The downstream end portion 105 b of the first deflecting plate 105 is located inside the furnace with respect to the downstream end portion 84 b of the downstream side plate 84. With such a configuration, the cross section inside the furnace, including the downstream end portion 105b of the first deflection plate 105 and orthogonal to the flow direction of the fuel gas in the flow path GP, has the upstream end portion 84a of the downstream side plate 84. The cross section perpendicular to the flow direction of the fuel gas in the flow path GP is smaller than the cross section inside the furnace. Thereby, the flow of the fuel gas having a high pulverized fuel concentration in the vicinity of the jet nozzle 81 can be biased further to the furnace inner side by the first deflector plate 105. As a result, the combustion burner 21 more reliably generates the high oxygen regions A1, A2, A3, and A4 outside the flames F1, F2, F3, and F4 approaching the furnace walls 11a, 11b, 11c, and 11d. It is possible to improve durability by suppressing corrosion of 11a, 11b, 11c, and 11d and suppressing adhesion of molten ash to the furnace walls 11a, 11b, 11c, and 11d.

  FIG. 16 is a cross-sectional view of the fuel supply pipe including the second deflecting plate according to the first embodiment of the present invention (EE section shown in FIG. 3). As shown in FIG. 16, a second deflecting plate 106 provided on the furnace wall side in the fuel supply pipe 26 near the jet port 81 is provided, and the first deflecting plate 105 deflects the fuel gas to the inside of the furnace. The downstream end portion 106b of the second deflecting plate 106 is positioned inside the furnace with respect to the upstream end portion 106a of the second deflecting plate 106. With such a configuration, the cross section inside the furnace, including the downstream end portion 105b of the first deflection plate 105 and orthogonal to the flow direction of the fuel gas in the flow path GP, has the upstream end portion 84a of the downstream side plate 84. The cross section perpendicular to the flow direction of the fuel gas in the flow path GP is smaller than the cross section inside the furnace. Accordingly, the flow of the fuel gas having a high pulverized fuel concentration is biased to the inside of the furnace by the first deflector plate 105, and the flow of the fuel gas having a low pulverized fuel concentration is also moved to the inside of the furnace by the second deflector plate 106. Can be biased. As a result, the combustion burner 21 more reliably generates the high oxygen regions A1, A2, A3, and A4 outside the flames F1, F2, F3, and F4 approaching the furnace walls 11a, 11b, 11c, and 11d. , F2, F3, and F4 can be further away from the furnace walls 11a, 11b, 11c, and 11d, the corrosion of the furnace walls 11a, 11b, 11c, and 11d is suppressed, and the furnace walls 11a, 11b, 11c, and 11d are melted. Durability can be improved by suppressing adhesion of ash.

  Further, in the combustion burner according to another aspect of the present invention, the downstream end portion of the downstream side plate 84 is located at the ejection port 81. With such a configuration, the flow path GP can be more reliably divided into a region where the pulverized coal concentration is high and a region where the pulverized coal concentration is low until the fuel gas is just ejected from the ejection port 81. As a result, the combustion burner 21 generates high oxygen regions A1, A2, A3, A4 outside the flames F1, F2, F3, F4 approaching the furnace walls 11a, 11b, 11c, 11d, and the furnace walls 11a, 11b. , 11c, 11d and the adhesion of the molten ash to the furnace walls 11a, 11b, 11c, 11d can be suppressed and durability can be improved.

DESCRIPTION OF SYMBOLS 10 Coal-fired boiler 11 Furnace 11a, 11b, 11c, 11d Furnace wall 12a, 12b, 12c, 12d Corner 13 Combustion device 21, 22, 23, 24, 25 Combustion burner 26, 27, 28, 29, 30 Fuel supply pipe 26a, 26b, 26c, 26d Branch pipes branched from the fuel supply pipe 26 31, 32, 33, 34, 35 Pulverized coal machine 36 Wind box 37 Air duct 37a, 37b, 37c, 37d Branch pipes branched from the air duct 37 Blower 41 Additional combustion air supply device 42, 43 Additional combustion air nozzle 51 Additional air supply device 52 Additional air nozzle 53 Branch air duct 70 Chimney 71, 72 Superheater 73, 74 Reheater 75, 76, 77 Device 78 exhaust gas pipe 79 air heater 81 spout 82 curved portion 82a upstream end 82b of curved portion 82 curved Downstream end portion 83, 101 Upstream side plate 83a, 101a Upstream end portion of upstream side plate 83b, 101b Downstream end portion of upstream side plate 84 Downstream side plate 84a, 102a, 103a, 104a Upstream end portion of downstream side plate 84b, 102b, 103b , Downstream end 86 of the downstream plate 86 curved portion 87 density separator 104b deflection unit 105 first deflection plate 106 second deflection plate A1, A2, A3, A4 high oxygen region F1, F2, F3, F4 F1, F2, F3, F4 Flame GF Flow direction of fuel gas GP Flow path S1 Cross-sectional area above and inside the furnace S2 Cross-sectional area above and the furnace wall side S3 Cross-sectional area below and the furnace wall side S4 Cross-sectional area below and inside the furnace X Horizontal axis Y Vertical axis Z Center axis of flow path GP θ, φ Angle

Claims (12)

A combustion burner for injecting fuel gas, which is a mixture of solid fuel and air, into a furnace from an outlet,
A fuel supply pipe installed along a vertical direction and having a curved portion that bends the flow of the fuel gas in a horizontal direction;
An upstream plate located downstream of the curved portion in the flow direction of the fuel gas and dividing the flow path of the fuel supply pipe into upper and lower portions;
A downstream plate that is located downstream of the upstream plate in the flow direction of the fuel gas and bisects the flow path to a furnace wall side that is closer to the furnace wall and a furnace inner side that is closer to the interior of the furnace;
With
When the flow path is viewed from the injection port, a cross section perpendicular to the flow direction of the fuel gas in the flow path is divided into a downstream end portion of the upstream side plate and an upstream end portion of the downstream side plate, The ratio of the upper and lower furnace wall side cross-sectional area to the sum of the upper and lower furnace wall side cross-sectional areas is smaller than the ratio of the upper and inner furnace cross-sectional area to the sum of the upper and lower furnace inner cross-sectional areas. Combustion burner characterized by. The cross section perpendicular to the flow direction of the fuel gas in the flow path is a circle or a rectangle provided with curved portions at four corners at a position including the upstream end portion of the downstream side plate, and four corners at a position including the jet port. Is a rectangle or a rectangle with a curved portion,
The upstream end of the upstream plate is located below the downstream end of the upstream plate,
The downstream end of the upstream plate is located above the central axis of the flow path,
2. The combustion burner according to claim 1, wherein an upstream end portion of the downstream side plate is located closer to a road wall than a central axis of the flow path. The cross section perpendicular to the flow direction of the fuel gas in the flow path is circular at any position including the fuel supply pipe from the downstream end of the curved portion to the jet port,
The upstream end of the upstream plate is located below the downstream end of the upstream plate,
The downstream end of the upstream plate is located above the central axis of the flow path,
2. The combustion burner according to claim 1, wherein an upstream end portion of the downstream side plate is located closer to a road wall than a central axis of the flow path. The combustion burner according to any one of claims 1 to 3, further comprising a density separator provided inside the fuel supply pipe immediately before the curved portion. The combustion burner according to any one of claims 1 to 4, wherein the upstream side plate is a curved plate protruding upward along the flow direction of the fuel gas. The combustion burner according to any one of claims 1 to 5, wherein a downstream end portion of the downstream plate is located inside the furnace with respect to an upstream end portion of the downstream plate. The combustion burner according to claim 6, wherein the downstream side plate is a curved plate convex toward the furnace wall along the flow direction of the fuel gas. The combustion burner according to claim 6, wherein the downstream end portion of the downstream side plate is a deflecting portion that deflects toward the inside of the furnace in the middle of the flow direction of the fuel gas. A first deflector plate positioned downstream of the downstream plate;
The upstream end of the first deflection plate is in contact with the downstream end of the downstream plate,
The combustion burner according to claim 6, wherein the downstream end portion of the first deflecting plate is located inside the furnace with respect to the downstream end portion of the downstream side plate. A second deflecting plate provided on the furnace wall side in the fuel supply pipe near the jet port, and along the deflection of the fuel gas into the furnace by the deflecting unit or the first deflecting plate, The combustion burner according to claim 9, wherein a downstream end portion of the second deflection plate is located inside the furnace with respect to an upstream end portion of the second deflection plate. The combustion burner according to any one of claims 1 to 8, wherein a downstream end portion of the downstream side plate is located at the ejection port. A furnace that is hollow and installed along the vertical direction;
At least one combustion burner according to any one of claims 1 to 11;
An additional air nozzle that blows additional air into the furnace above the combustion burner;
The boiler characterized by having.

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