JP2015117862A - Boiler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve durability of a boiler by preventing corrosion of a furnace wall with a simple configuration.SOLUTION: A boiler includes: a furnace 11 formed into a hollow shape and installed vertically; combustion burners 21, 22, 23, 24, and 25 that can produce flame swirl flows by injecting pulverized fuel-air mixture into the furnace 11; additional combustion air nozzles 42 and 43 injecting additional combustion air into the furnace 11 above the combustion burners 21, 22, 23, 24, and 25; and an additional air nozzle 52 that includes first nozzles 54a, 54b, 54c, and 54d injecting additional air into the furnace 11 above the additional combustion air nozzles 42 and 43, and second nozzles 55a, 55b, 55c, and 55d injecting additional air along an inner wall surface of the furnace 11.

Description

  The present invention relates to a boiler that generates steam by mixing and burning solid fuel and air.

  Conventional coal-fired boilers have a hollow furnace that is installed in a vertical direction, and a plurality of combustion burners are arranged on the furnace wall along the circumferential direction and arranged in multiple stages in the vertical direction. ing. The combustion burner is supplied with a mixture of pulverized coal (fuel) obtained by pulverizing coal and primary air (carrier air), and also supplied with high-temperature secondary air. The mixture and secondary air are supplied to the combustion burner. Is blown into the furnace to form a flame that can be burned 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. Accordingly, the combustion burner forms a flame by blowing a pulverized fuel mixture in which pulverized coal and carrier air are mixed into the furnace and blowing combustion air into the furnace and igniting. The additional air nozzle blows additional 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 air is additionally supplied to complete the oxidative combustion of the pulverized coal, thereby reducing the amount of NOx generated by the combustion of the pulverized coal.

By the way, in such a furnace, in a reducing atmosphere region, a low oxygen region and a high temperature region, hydrogen sulfide (H ₂ S), which is a corrosive component, is likely to be generated, and the inner surface of the furnace wall There is a risk of corrosion. Therefore, as a solution to such a problem, for example, there is one described in the following patent document.

  The combustion apparatus of the pulverized coal burning boiler described in the following Patent Document 1 is provided with a nozzle for introducing a part of combustion air or combustion gas between adjacent burners. The boiler structure described in the following Patent Document 2 is provided with an air input part that forms a region having a higher air concentration than the surroundings in the vicinity of the flame affected part of the furnace wall where the flame formed for each burner approaches or contacts. is there.

Japanese Patent Laid-Open No. 07-119923 JP 2009-174751 A

  As described in the above-mentioned patent documents, when a nozzle for injecting combustion air and an air input unit are provided separately from the burner, there is a problem that the structure of the boiler becomes complicated and the manufacturing cost increases.

  The present invention solves the above-described problems, and an object of the present invention is to provide a boiler that improves durability by preventing corrosion of a furnace wall with a simple configuration.

  In order to achieve the above object, a boiler according to the present invention has a hollow furnace that is installed along a vertical direction, and a fuel gas mixed with solid fuel and combustion air is blown into the furnace. A combustion burner capable of forming a flame swirl flow, an additional combustion air nozzle for blowing additional combustion air into the furnace above the combustion burner, and an additional air above the additional combustion air nozzle. And an additional air nozzle having a first nozzle that blows into the furnace and a second nozzle that blows additional air along the inner wall surface of the furnace.

  Accordingly, the combustion burner blows fuel gas into the furnace, and the first nozzle of the additional combustion air nozzle blows combustion air into the furnace to form a flame swirl, and the generated combustion gas swirls from the combustion region. While rising. The fuel gas is set so that the amount of air is less than the theoretical amount of air with respect to the solid fuel, so that a reduction region is formed above the combustion region. Here, harmful substances generated by the combustion of the solid fuel are generated. Reduced. Thereafter, the additional air nozzle blows the additional air into the furnace, whereby the oxidative combustion of the solid fuel is completed. At this time, since the second nozzle of the additional air nozzle blows air along the inner wall surface of the furnace, direct contact between the combustion gas and the inner wall surface of the furnace is suppressed, and corrosion of the furnace wall is prevented and durable. Can be improved.

  In the boiler according to the present invention, the furnace has a rectangular cross-sectional shape, and the additional air nozzle is arranged at a corner of the furnace.

  Therefore, the raised combustion gas can be properly discharged to the downstream side without staying in the corner of the furnace.

  In the boiler according to the present invention, the combustion burner is disposed at a corner portion of the furnace, and the additional air nozzle is disposed at a corner portion of the furnace above the combustion burner, so that the fuel gas from the combustion burner is horizontally disposed. The blowing angle in the direction and the blowing angle in the horizontal direction of the additional air from the first nozzle are set to be substantially the same angle.

  Therefore, the first nozzle blows air to an appropriate position with respect to the flame swirl flow formed and raised by the combustion burner, and the combustion gas can be properly discharged downstream.

  The boiler according to the present invention is characterized in that an air injection amount adjusting device is provided for adjusting a ratio between an injection amount of the additional air from the first nozzle and an injection amount of the additional air from the second nozzle.

  Therefore, the optimal combustion state is obtained by increasing or decreasing the injection amount of the additional air from the first nozzle and the injection amount of the additional air from the second nozzle by the air injection amount adjusting device according to the combustion state of the combustion gas in the furnace. Can be maintained.

  In the boiler according to the present invention, the first nozzle and the second nozzle are arranged so as to be shifted in the vertical direction.

  Therefore, by arranging the first nozzle and the second nozzle so as to be shifted in the vertical direction, the region of air blown into the furnace and the region of air blown along the inner wall surface of the furnace are made to be different regions in the upper and lower sides. Thus, an optimum flame swirl flow can be formed, and the high temperature of the furnace wall can be appropriately suppressed.

  The boiler according to the present invention is characterized in that an air injection direction up / down adjustment device capable of adjusting the injection direction of at least the additional air from the second nozzle up and down is provided.

  Therefore, by adjusting the injection direction of the additional air from the second nozzle up and down by the air injection direction up-and-down adjustment device, it is possible to appropriately inject air into a region where corrosion on the inner wall surface of the furnace is likely to occur.

  The boiler according to the present invention is characterized in that an air injection direction left / right adjustment device capable of adjusting at least the injection direction of the additional air from the second nozzle to the left and right is provided.

  Therefore, by adjusting the injection direction of the additional air from the second nozzle to the left and right by the air injection direction left / right adjustment device, it is possible to properly inject air into a region where corrosion on the inner wall surface of the furnace is likely to occur.

  In the boiler according to the present invention, the additional air nozzle has a third nozzle that blows in additional air along an inner wall surface different from the second nozzle in the furnace.

  Therefore, by blowing air along all the inner wall surfaces in the furnace, it is possible to effectively suppress the temperature rise of the furnace wall.

  The boiler according to the present invention is characterized in that a blower for increasing a flow rate of the additional air ejected by the second nozzle is provided.

  Therefore, by increasing the flow rate of the additional air that is ejected by the second nozzle by the blower, it is possible to effectively suppress the temperature increase of the furnace wall by spreading more air on the inner wall surface of the furnace.

  In the boiler according to the present invention, the additional air nozzle can blow at least a part of the exhaust gas discharged from the furnace into the furnace.

  Therefore, the additional air nozzle can suppress the temperature reduction of the inner wall surface of the furnace by supplying at least a part of the exhaust gas as additional air to the furnace.

  According to the boiler of the present invention, since the additional air nozzle for blowing additional air along the inner wall surface of the furnace is provided above the combustion burner, direct contact between the combustion gas and the inner wall surface of the furnace is suppressed, and the furnace wall The corrosion can be prevented and the durability can be improved.

Drawing 1 is a schematic structure figure showing a coal burning boiler of a 1st embodiment. FIG. 2 is a plan view of a combustion burner in a coal fired boiler. FIG. 3 is a plan view of the additional air nozzle in the coal fired boiler. FIG. 4 is a plan view showing a NOx reduction region in a coal fired boiler. FIG. 5 is a plan view of an additional air nozzle in the coal fired boiler according to the second embodiment. FIG. 6 is a plan view of an additional air nozzle in the coal fired boiler according to the third embodiment. FIG. 7 is a perspective view of the additional air nozzle. FIG. 8 is a plan view of an additional air nozzle in the coal fired boiler according to the fourth embodiment. FIG. 9 is a plan view of an additional air nozzle in the coal fired boiler according to the fifth embodiment. FIG. 10 is a schematic configuration diagram illustrating a coal fired boiler according to a sixth embodiment.

  Hereinafter, preferred embodiments of a boiler according to the present invention will be described 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. 1 is a schematic configuration diagram illustrating a coal-fired boiler according to the first embodiment, FIG. 2 is a plan view of a combustion burner in the coal-fired boiler, and FIG. 3 is a plan view of an additional combustion air nozzle in the coal-fired boiler. 4 is a plan view showing a NOx reduction region in a coal fired boiler.

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

  In this 1st Embodiment, as shown in FIG. 1, the coal burning boiler 10 is a conventional boiler, Comprising: The furnace 11 and the combustion apparatus 12 are provided. 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. And the combustion apparatus 12 is arrange | positioned as 5 sets along the vertical direction, ie, 5 steps | paragraphs, as one set in which the four combustion burners were arrange | positioned at equal intervals along the circumferential direction. 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 embodiment. It is not a thing.

  Each combustion burner 21, 22, 23, 24, 25 is connected to a pulverized coal machine (mill) 31, 32, 33, 34, 35 via a pulverized coal supply pipe 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 configured to be rotatably supported in conjunction with the rotation of the crushing table. Accordingly, when coal is introduced between a plurality of crushing rollers and a crushing table, the pulverized coal supplied to the pulverized coal supply pipe 26 is pulverized to a predetermined size and classified by transporting air (primary air). 27, 28, 29, 30 can be supplied to the combustion burners 21, 22, 23, 24, 25.

  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. Is equipped with a blower 38 at the other end. Therefore, the combustion air (secondary air) sent by the blower 38 is supplied from the air duct 37 to the wind box 36 and supplied from the wind box 36 to the combustion burners 21, 22, 23, 24, 25. it can.

  Here, although the combustion apparatus 12 is demonstrated in detail, since each combustion burner 21, 22, 23, 24, 25 which comprises this combustion apparatus 12 has comprised the substantially the same structure, it is located in the uppermost stage. Only the combustion burner 21 will be described.

  As shown in FIG. 2, the combustion burner 21 includes combustion burners 21 a, 21 b, 21 c, and 21 d provided at four corners 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 coal 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 at each corner of the furnace 11 blows into the furnace 11 a pulverized fuel mixture (fuel gas) in which pulverized coal and carrier air are mixed, Combustion air is blown outside the pulverized fuel mixture. Then, by igniting the pulverized fuel mixture from each combustion burner 21a, 21b, 21c, 21d, four flames F1, F2, F3, F4 can be formed, and this flame F1, F2, F3, F4. Is a flame swirl flow swirling counterclockwise as viewed from above the furnace 11 (in FIG. 2).

  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 12. The additional combustion air supply device 41 has a plurality of additional combustion air nozzles 42 and 43 attached to the furnace wall 11a. The additional combustion air nozzles 42, 43 are arranged in a set of four at regular intervals along the circumferential direction, and two sets, that is, two stages, are arranged along the vertical direction. That is, the additional combustion air supply device 41 (additional combustion air nozzles 42, 43) is 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. The additional combustion air nozzles 42 and 43 are connected to the ends of the first branch air duct 44 branched from the air duct 37.

  Therefore, the combustion air sent by the blower 38 can be supplied from the first branch air duct 44 to the additional combustion air nozzles 42 and 43. Further, the additional combustion air nozzles 42 and 43 can blow additional combustion air above the pulverized fuel mixture blown by the combustion burners 21, 22, 23, 24 and 25.

  The furnace 11 is provided with an additional air supply device 51 above the combustion device 12 and the additional combustion air supply device 41. The additional air supply device 51 has a plurality of additional air nozzles 52 mounted on the furnace wall 11a. One set of the additional air nozzles 52 arranged at equal intervals along the circumferential direction, that is, one stage is arranged. In other words, the additional air supply device 51 (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 four corners in the furnace 11, similar to the combustion burners 21, 22, 23, 24, 25, and is similar to the flame swirl flow. An additional air swirl is formed. The additional air nozzle 52 is connected to the end of a second branch air duct 53 branched from the air duct 37.

  Here, the additional air supply device 51 will be described in detail.

  As shown in FIG. 3, the additional air nozzle 52 is composed of additional air nozzles 52a, 52b, 52c, and 52d provided at four corners in the furnace 11, as with the combustion burners 21, 22, 23, 24, and 25. Has been. Each additional air nozzle 52a, 52b, 52c, 52d includes a first nozzle 54a, 54b, 54c, 54d for blowing additional air into the furnace 11, and a second nozzle for blowing additional air along the inner wall surface of the furnace 11. 55a, 55b, 55c, and 55d, and can inject air in two different horizontal directions. The second nozzles 55 a, 55 b, 55 c, and 55 d are preferably blown downward along the inner wall surface of the furnace 11.

  The horizontal blowing angle of the additional air from the first nozzles 54a, 54b, 54c, 54d is substantially the same as the horizontal blowing angle of the pulverized fuel mixture from the combustion burners 21a, 21b, 21c, 21d. Is set. On the other hand, the second nozzles 55a, 55b, 55c, and 55d can inject additional air in the horizontal direction along the inner wall surface of the furnace wall 11a. Each additional air nozzle 52a, 52b, 52c, 52d is connected to each branch pipe 53a, 53b, 53c, 53d branched from the second branch air duct 53.

  Therefore, the combustion air sent by the blower 38 can be supplied from the second branch air duct 53 to the additional air nozzles 52a, 52b, 52c, 52d via the branch pipes 53a, 53b, 53c, 53d. The first nozzles 54a, 54b, 54c, 54d can inject the air streams A1, A2, A3, A4 above the pulverized fuel mixture blown by the combustion burners 21a, 21b, 21c, 21d. The two nozzles 55a, 55b, 55c, and 55d can inject the air flows A11, A12, A13, and A14 along the inner wall surface of the furnace wall 11a.

  As described above, the combustion burners 21, 22, 23, 24, and 25 are flames by blowing pulverized fuel mixture (fuel gas) mixed with pulverized coal and carrier air and secondary air into the furnace 11. A swirling flow can be formed. Further, the additional combustion air nozzles 42, 43 can blow additional combustion air into the furnace 11 at the upper stage of the combustion burners 21, 22, 23, 24, 25. Further, the additional air nozzle 52 can blow additional air into the furnace 11 above the combustion burners 21, 22, 23, 24, 25.

  Then, as shown in FIG. 4, the first nozzles 54a, 54b, 54c, 54d of the additional air nozzle 52 are placed above the air swirl flow F formed by the combustion burners 21a, 21b, 21c, 21d. A2, A3 and A4 are formed. On the other hand, the second nozzles 55a, 55b, 55c, and 55d form air flows A11, A12, A13, and A14 between the flame swirl flow F and the inner wall surface of the furnace wall 11a. Therefore, direct contact of the flame swirl flow F with the inner wall surface of the furnace wall 11a is suppressed by the air flows A11, A12, A13, and A14, and heating of the inner wall surface of the furnace wall 11a is prevented.

  In addition, each combustion burner 21, 22, 23, 24, 25 which constitutes the combustion apparatus 12 of the present embodiment has an oil nozzle capable of injecting oil fuel at the center and a fine fuel mixture outside the oil nozzle. An injectable fuel nozzle and a secondary air nozzle capable of injecting secondary air outside the fuel nozzle are provided. 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 the fine fuel mixture and secondary air are introduced into the furnace 11. A flame is formed by spraying.

  As shown in FIG. 1, the furnace 11 has a flue 70 connected to the upper portion thereof, and a superheater (superheater) 71 for recovering the heat of exhaust gas as a convection heat transfer section to the flue 70. , 72, reheaters (reheaters) 73, 74, and economizers 75, 76, 77 are provided, and heat exchange is performed between the exhaust gas generated by 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 gas pipe 78 is provided with an air heater 79 between the air duct 37 and performs heat exchange between the air flowing through the air duct 37 and the exhaust gas flowing through the exhaust gas pipe 78, and the combustion burners 21, 22, 23, The temperature of the combustion air supplied to 24 and 25 can be raised.

  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 in the coal-fired boiler 10 configured as described above, the generated pulverized coal together with the air for conveyance is pulverized coal supply pipes 26, 27, 28, and 29. , 30 to the combustion burners 21, 22, 23, 24, 25. Also, heated combustion air is supplied from the air duct 37 to the combustion burners 21, 22, 23, 24, 25 via the wind box 36. The heated combustion air is supplied to the additional combustion air nozzles 42 and 43 and the additional air nozzle 52 by the branched air ducts 44 and 53 branched from the air duct 37.

  Then, the combustion burners 21, 22, 23, 24, 25 blow the pulverized fuel mixture mixture of pulverized coal and carrier air and the secondary air into the furnace 11, and ignite at this time to enter the combustion region A. A flame swirl can be formed. Further, 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, when the pulverized fuel mixture, the secondary air, and the additional combustion air are burned to generate a flame swirl, and a flame swirl is generated in the combustion region A, the combustion gas (exhaust gas) swirls in the furnace 11. It rises while reaching the reduction region B.

  At this time, in the furnace 11, the combustion burners 21, 22, 23, 24, and 25 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 A 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 (first nozzle) blows additional air above the reduction region B of the furnace 11. Then, in the combustion completion region C, the exhaust gas reacts with the additional air, whereby the oxidative combustion of the pulverized coal is completed, and the amount of NOx generated by the combustion of the pulverized coal is reduced.

By the way, in the reduction region B of the furnace 11, since it is a low-oxygen atmosphere and a high-temperature atmosphere, hydrogen sulfide (H ₂ S), which is a corrosive component, is easily generated, and corrosion occurs on the inner surface of the furnace wall 11a. There is a fear. Therefore, in the present embodiment, in the furnace 11, the additional air nozzle 52 (second nozzle) blows in additional air along the inner wall surface of the furnace wall 11a in the reduction region B. Since this additional air is blown outward from the flame swirl flow, the flame does not directly contact the inner wall surface of the furnace wall 11a, and the occurrence of corrosion is suppressed by lowering the temperature of the furnace wall 11a.

  In addition, since air is blown between the additional air nozzle 52 (second nozzle) between the inner wall surface of the furnace wall 11a and the flame swirl flow, this region becomes a high oxygen region, and generation of hydrogen sulfide is suppressed. Therefore, corrosion of the furnace wall 11a is suppressed. Furthermore, the furnace 11 can suppress the melting of fly ash and prevent slagging because the reduction region B is suppressed to a high oxygen atmosphere and a low temperature atmosphere.

  The additional air nozzle 52 (second nozzle) may disturb the reduction region B by blowing air into the reduction region B. However, the air from the additional air nozzle 52 (second nozzle) is swirled by flame. Since it is outside the flow, this air hardly affects the NOx reduction action.

  The water supplied from a water supply pump (not shown) is preheated by the economizers 75, 76, and 77, then supplied to a steam drum (not shown) and supplied to each water pipe (not shown) on the furnace wall. It is heated to become saturated steam and fed into a steam drum (not shown). Further, saturated steam of a steam drum (not shown) is introduced into the superheaters 71 and 72 and is heated by the combustion gas. The superheated steam generated by the superheaters 71 and 72 is supplied to a power plant (not shown) (for example, a turbine). Further, the steam taken out in the middle of the expansion process in the turbine is introduced into the reheaters 73 and 74, overheated again, and returned to the turbine. In addition, although the furnace 11 was demonstrated as a drum type | mold (steam drum), it is not limited to this structure.

  Thereafter, the exhaust gas that has passed through the economizers 75, 76, and 77 of the flue 70 is subjected to removal of harmful substances such as NOx by a catalyst in a denitration device (not shown) in the exhaust gas pipe 78, and the particulate matter is collected by an electric dust collector. Is removed, and after the sulfur content is removed by the desulfurizer, it is discharged from the chimney into the atmosphere.

  As described above, in the boiler according to the first embodiment, a flame swirl flow is formed by blowing the pulverized fuel mixture into the furnace 11 and the furnace 11 installed along the vertical direction in a hollow shape. Possible combustion burners 21, 22, 23, 24, 25, and additional combustion air nozzles 42, 43 for blowing additional combustion air into the furnace 11 above the combustion burners 21, 22, 23, 24, 25; The first nozzles 54a, 54b, 54c and 54d for blowing additional air into the furnace 11 above the additional combustion air nozzles 42 and 43, and the second nozzle 55a for blowing additional air along the inner wall surface of the furnace 11. An additional air nozzle 52 having 55b, 55c and 55d is provided.

  Accordingly, the combustion burners 21, 22, 23, 24, and 25 blow the pulverized fuel mixture into the furnace 11, and the additional combustion air nozzles 42 and 43 blow the combustion air into the furnace 11, thereby generating a flame swirl. The formed and generated combustion gas rises while swirling from the combustion region A. The pulverized fuel mixture is set so that the amount of air is less than the theoretical amount of air with respect to the pulverized coal fuel, so that a reduction region B is formed above the combustion region A. Here, the combustion of the pulverized coal fuel NOx generated by the above is reduced. Thereafter, the first nozzles 54a, 54b, 54c, 54d of the additional air nozzle 52 blow in additional air into the furnace 11, whereby the oxidative combustion of the pulverized coal is completed. At this time, the second nozzles 55a, 55b, 55c, 55d of the additional air nozzle 52 blows air along the inner wall surface of the furnace wall 11a between the combustion area A and the reduction area B, so that the combustion gas and the furnace Direct contact with the inner wall surface of the wall 11a is suppressed, and corrosion of the furnace wall 11a can be prevented and durability can be improved.

  In this case, the second nozzle 55a that blows additional air along the inner wall surface of the furnace 11 with respect to the first nozzles 54a, 54b, 54c, and 54d that blows additional air into the furnace 11 at the additional air nozzle 52. , 55b, 55c, and 55d only need to be added, and the manufacturing cost can be reduced by reducing the number of modifications to the existing boiler.

  In the boiler according to the first embodiment, the furnace 11 has a rectangular cross-sectional shape, and the additional air nozzle 52 is arranged at the corners above the combustion burners 21, 22, 23, 24, 25 in the furnace 11. Therefore, the first nozzles 54 a, 54 b, 54 c, 54 d of the additional air nozzle 52 appropriately inject additional air with respect to the flame swirl flow that has risen in the furnace 11, so that the combustion gas is directed to the corners of the furnace 11. Without staying, it can be properly discharged downstream.

  In the boiler according to the first embodiment, the combustion burners 21, 22, 23, 24, 25 are arranged at the corners of the furnace 11, and the additional air nozzle 52 is located above the combustion burners 21, 22, 23, 24, 25 in the furnace 11. Of the pulverized coal mixture from the combustion burners 21, 22, 23, 24, 25 in the horizontal direction and the horizontal direction of the additional combustion air from the first nozzles 54a, 54b, 54c, 54d. The blowing angle in the direction is set to substantially the same angle. Therefore, the first nozzles 54a, 54b, 54c, 54d blow air into the proper position with respect to the flame swirl flow formed by the combustion burners 21, 22, 23, 24, 25, and the optimum flame swirl. A flow can be formed.

[Second Embodiment]
FIG. 5 is a plan view of an additional combustion air nozzle in the coal fired boiler according to the second embodiment. Note that the basic configuration of the boiler of the present embodiment is substantially the same as that of the first embodiment described above, and will be described with reference to FIG. The same reference numerals are attached and detailed description is omitted.

  In the second embodiment, as shown in FIG. 1, the coal fired boiler 10 includes a furnace 11 and a combustion device 12, and the combustion device 12 includes a plurality of combustion burners 21, 22, 23, 24, 25. have. The combustion apparatus 12 includes five combustion burners arranged at equal intervals along the circumferential direction as one set, and five sets along the vertical direction, that is, five stages. Each combustion burner 21, 22, 23, 24, 25 is connected to a pulverized coal machine 31, 32, 33, 34, 35 via a pulverized coal supply pipe 26, 27, 28, 29, 30.

  As shown in FIGS. 1 and 5, the furnace 11 is provided with an additional combustion air supply device 41 above the combustion device 12. The additional combustion air supply device 41 includes additional combustion air nozzles 42 and 43 attached to the furnace wall 11 a, and the end of the first branch air duct 44 branched from the air duct 37 is connected. Yes. The furnace 11 is provided with an additional air supply device 81 above the additional combustion air supply device 41. This additional air supply device 81 has a plurality of additional air nozzles 82 mounted on the furnace wall 11 a, and the end of the second branch air duct 53 branched from the air duct 37 is connected.

  Here, the additional air supply device 81 will be described in detail. As shown in FIG. 5, the additional air nozzle 82 includes additional air nozzles 82 a, 82 b, 82 c, and 82 d provided at four corners in the furnace 11. Each additional air nozzle 82a, 82b, 82c, 82d includes a first nozzle 83a, 83b, 83c, 83d that blows additional air into the furnace 11, and a second nozzle that blows additional air along the inner wall surface of the furnace 11. 84a, 84b, 84c, 84d, and can inject air in two different horizontal directions.

  Here, the horizontal blowing angle of the additional air from the first nozzles 83a, 83b, 83c, 83d is the horizontal blowing direction of the pulverized coal mixture from the combustion burners 21a, 21b, 21c, 21d (see FIG. 2). It is set to the same angle as the angle. On the other hand, the second nozzles 84a, 84b, 84c, 84d can inject additional air in the horizontal direction along the inner wall surface of the furnace wall 11a. Each additional air nozzle 82a, 82b, 82c, 82d is connected to each branch pipe 53a, 53b, 53c, 53d branched from the second branch air duct 53.

  The additional air nozzle 82 adjusts the ratio of the additional air injection amount from the first nozzles 83a, 83b, 83c, 83d and the additional air injection amount from the second nozzles 84a, 84b, 84c, 84d. An air injection amount adjusting device is provided. That is, the first nozzles 83a, 83b, 83c, and 83d are connected to the branch pipes 53a, 53b, 53c, and 53d via the pipes 85a, 85b, 85c, and 85d, and the flow paths are connected to the pipes 85a, 85b, 85c, and 85d. Dampers 86a, 86b, 86c, 86d having adjustable areas are provided. On the other hand, the second nozzles 84a, 84b, 84c, and 84d are connected to the branch pipes 53a, 53b, 53c, and 53d through the pipes 87a, 87b, 87c, and 87d, and the flow paths are connected to the pipes 87a, 87b, 87c, and 87d. Dampers 88a, 88b, 88c, and 88d having adjustable areas are provided.

  Further, the additional air supply device 81 is provided with an air injection direction up / down adjustment device that can adjust the injection direction of the additional air from the second nozzles 84a, 84b, 84c, 84d up and down. That is, the second nozzles 84a, 84b, 84c, and 84d are rotatable in the horizontal direction by the support shafts 89a, 89b, 89c, and 89d along the horizontal direction, and can be driven by the driving devices 90a, 90b, 90c, and 90d. It has become.

  Therefore, the additional air can be supplied from the second branch air duct 53 to the additional air nozzles 82a, 82b, 82c, and 82d via the branch pipes 53a, 53b, 53c, and 53d. The first nozzles 83a, 83b, 83c, 83d can inject the airflows A1, A2, A3, A4, and the second nozzles 84a, 84b, 84c, 84d are along the inner wall surface of the furnace wall 11a. Thus, the air flows A12, A12, A13, A14 can be injected.

  Further, by changing the opening degree of the dampers 86a, 86b, 86c, 86d and the dampers 88a, 88b, 88c, 88d, the first nozzles 83a, 83b, 83c, 83d and the second nozzles 84a, 84b, 84c, 84d are changed. The additional air injection amount (injection ratio) can be adjusted. For example, when a NOx sensor is provided in the flue 70 of the furnace 11 and the amount of NOx in the combustion gas increases, the injection amount (injection ratio) of additional air from the second nozzles 84a, 84b, 84c, 84d is increased. In addition, when an unburned component sensor is provided in the flue 70 of the furnace 11 and the amount of unburned component in the combustion gas increases, the injection amount (injection ratio) of additional air from the first nozzles 83a, 83b, 83c, 83d increases. To do.

  Furthermore, by driving the driving devices 90a, 90b, 90c, and 90d, it is possible to adjust the injection direction of the additional air by the second nozzles 84a, 84b, 84c, and 84d. For example, a temperature sensor that measures the temperature of the furnace wall 11a is provided in the furnace 11, and the driving devices 90a, 90b, 90c, and 90d are configured to inject additional air toward a region where the temperature of the furnace wall 11a is high. The two nozzles 84a, 84b, 84c, 84d are rotated by the support shafts 89a, 89b, 89c, 89d to adjust the positions.

  As shown in FIGS. 1 and 5, the combustion burners 21, 22, 23, 24, and 25 are provided with pulverized fuel mixture (fuel gas) in which pulverized coal and carrier air are mixed, and secondary air in the furnace 11. A flame swirl can be formed by blowing toward The additional combustion air nozzles 42 and 43 can blow additional air into the furnace 11 above the combustion burners 21, 22, 23, 24, and 25. Further, the additional air nozzle 82 can blow additional air into the furnace 11 above the combustion burners 21, 22, 23, 24, 25.

  Here, the additional air nozzle 82 blows in additional air along the inner wall surface of the furnace wall 11a in which the second nozzles 84a, 84b, 84c, and 84d are in the reduction region B. Since this additional air is blown outward from the flame swirl flow, the flame does not directly contact the inner wall surface of the furnace wall 11a, and the occurrence of corrosion is suppressed by lowering the temperature of the furnace wall 11a.

  As described above, the boiler according to the second embodiment is additionally provided with the first nozzles 83a, 83b, 83c, 83d for blowing additional air into the furnace 11 above the combustion burners 21, 22, 23, 24, 25. An additional air nozzle 82 having second nozzles 84a, 84b, 84c, and 84d for blowing air along the inner wall surface of the furnace 11 is provided, and the amount of additional air injected from the first nozzles 83a, 83b, 83c, and 83d, and Dampers 86a, 86b, 86c, 86d, 88a, 88b, 88c, and 88d are provided as an air injection amount adjusting device that adjusts the ratio of the additional air from the second nozzles 84a, 84b, 84c, and 84d. .

  Therefore, the second nozzles 84a, 84b, 84c, 84d of the additional air nozzle 82 blows air along the inner wall surface of the furnace wall 11a, thereby suppressing direct contact between the combustion gas and the inner wall surface of the furnace wall 11a. As a result, corrosion of the furnace wall can be prevented and durability can be improved. Further, the air injection amount adjusting device increases or decreases the injection amount of additional air from the first nozzles 83a, 83b, 83c, 83d and the injection amount of additional air from the second nozzles 84a, 84b, 84c, 84d. A stable combustion state can be maintained.

  In the boiler according to the second embodiment, the second nozzles 84a, 84b, 84c, and 84d are used as an air injection direction vertical adjustment device that can adjust the injection direction of the additional air from the second nozzles 84a, 84b, 84c, and 84d up and down. Support shafts 89a, 89b, 89c, 89d and driving devices 90a, 90b, 90c, 90d are provided. Therefore, it is possible to properly inject air into a region where corrosion on the inner wall surface of the furnace 11 is likely to occur.

  In the second embodiment, the second nozzles 84a, 84b, 84c, 84d are adjustable in the vertical direction, but the first nozzles 83a, 83b, 83c, 83d may be adjustable in the vertical direction.

[Third Embodiment]
FIG. 6 is a plan view of an additional air nozzle in the coal fired boiler according to the third embodiment, and FIG. 7 is a perspective view of the additional air nozzle. Note that the basic configuration of the boiler of the present embodiment is substantially the same as that of the first embodiment described above, and will be described with reference to FIG. The same reference numerals are attached and detailed description is omitted.

  In 3rd Embodiment, as shown in FIG. 1, the coal burning boiler 10 has the furnace 11 and the combustion apparatus 12, and the combustion apparatus 12 is the some combustion burner 21,22,23,24,25. have. The combustion apparatus 12 includes five combustion burners arranged at equal intervals along the circumferential direction as one set, and five sets along the vertical direction, that is, five stages. Each combustion burner 21, 22, 23, 24, 25 is connected to a pulverized coal machine 31, 32, 33, 34, 35 via a pulverized coal supply pipe 26, 27, 28, 29, 30.

  As shown in FIGS. 1 and 6, the furnace 11 is provided with an additional combustion air supply device 41 above the combustion device 12. The additional combustion air supply device 41 includes additional combustion air nozzles 42 and 43 attached to the furnace wall 11 a, and the end of the first branch air duct 44 branched from the air duct 37 is connected. Yes. The furnace 11 is provided with an additional air supply device 91 above the additional combustion air supply device 41. The additional air supply device 91 has a plurality of additional air nozzles 92 mounted on the furnace wall 11 a and is connected to the end of a second branch air duct 53 branched from the air duct 37.

  Here, the additional air supply device 91 will be described in detail. As shown in FIG. 6, the additional air nozzle 92 includes additional air nozzles 92 a, 92 b, 92 c, and 92 d provided at four corners of the furnace 11. Each additional air nozzle 92a, 92b, 92c, 92d includes a first nozzle 93a, 93b, 93c, 93d for blowing additional air into the furnace 11, and a second nozzle for blowing additional air along the inner wall surface of the furnace 11. 94a, 94b, 94c, 94d, and can inject air in two different horizontal directions.

  The first nozzles 93 a, 93 b, 93 c, 93 d and the second nozzles 94 a, 94 b, 94 c, 94 d are arranged in the furnace 11 so as to be shifted in the vertical direction. In the present embodiment, the first nozzles 93a, 93b, 93c, and 93d are located on the upper side, and the second nozzles 94a, 94b, 94c, and 94d are located on the lower side. However, the first nozzles 93a, 93b, 93c, and 93d may be positioned on the lower side, and the second nozzles 94a, 94b, 94c, and 94d may be positioned on the upper side.

  Further, the additional air supply device 91 is provided with an air injection direction left / right adjustment device capable of adjusting the injection direction of the additional air from the second nozzles 94a, 94b, 94c, 94d to the left and right. That is, as shown in detail in FIG. 7, the second nozzles 94a, 94b, 94c, and 94d are rotatable in the horizontal direction by the support shafts 95a, 95b, 95c, and 95d along the vertical direction, and the driving devices 96a, Driven by 96b, 96c, 96d. For example, a temperature sensor that measures the temperature of the furnace wall 11a is provided in the furnace 11, and the driving devices 96a, 96b, 96c, and 96d are configured to inject additional air toward a region where the temperature of the furnace wall 11a is high. The two nozzles 94a, 94b, 94c, 94d are rotated by the support shafts 95a, 95b, 95c, 95d to adjust their positions.

  Therefore, the combustion air can be supplied from the second branch air duct 53 to the additional air nozzles 92a, 92b, 92c, and 92d via the branch pipes 53a, 53b, 53c, and 53d. The first nozzles 93a, 93b, 93c, and 93d can inject the air flows A1, A2, A3, and A4, and the second nozzles 94a, 94b, 94c, and 94d are along the inner wall surface of the furnace wall 11a. Thus, the air flows A12, A12, A13, A14 can be injected.

  As shown in FIGS. 1 and 6, the combustion burners 21, 22, 23, 24, and 25 are provided with pulverized fuel mixture (fuel gas) in which pulverized coal and carrier air are mixed, and secondary air in the furnace 11. A flame swirl can be formed by blowing toward Further, the additional combustion air nozzles 42, 43 can blow additional combustion air into the furnace 11 above the combustion burners 21, 22, 23, 24, 25. Further, the additional air nozzle 92 can blow additional air into the furnace 11 above the combustion burners 21, 22, 23, 24, 25.

  Further, by driving the driving devices 96a, 96b, 96c, and 96d, it is possible to adjust the injection direction of the additional air by the second nozzles 94a, 94b, 94c, and 94d. For example, a temperature sensor that measures the temperature of the furnace wall 11a is provided in the furnace 11, and the driving devices 96a, 96b, 96c, and 96d are configured to inject additional air toward a region where the temperature of the furnace wall 11a is high. The two nozzles 94a, 94b, 94c, 94d are rotated by the support shafts 95a, 95b, 95c, 95d to adjust their positions.

  Here, in the additional air nozzle 92, the second nozzles 94a, 94b, 94c, and 94d blow in additional air along the inner wall surface of the furnace wall 11a in the reduction region B. Since this additional air is blown outward from the flame swirl flow, the flame does not directly contact the inner wall surface of the furnace wall 11a, and the occurrence of corrosion is suppressed by lowering the temperature of the furnace wall 11a.

  As described above, in the boiler according to the third embodiment, the first nozzles 93a, 93b, 93c, and 93d for blowing additional air into the furnace 11 above the combustion burners 21, 22, 23, 24, and 25 are added. An additional air nozzle 92 having second nozzles 94a, 94b, 94c, 94d for blowing air along the inner wall surface of the furnace 11 is provided, and the first nozzles 93a, 93b, 93c, 93d and the second nozzles 94a, 94b, 94c are provided. 94d are arranged in the furnace 11 so as to be shifted in the vertical direction.

  Therefore, the second nozzles 94a, 94b, 94c, 94d of the additional air nozzle 92 blows air along the inner wall surface of the furnace wall 11a, thereby suppressing direct contact between the combustion gas and the inner wall surface of the furnace wall 11a. As a result, corrosion of the furnace wall can be prevented and durability can be improved. In addition, by disposing the first nozzles 93a, 93b, 93c, 93d and the second nozzles 94a, 94b, 94c, 94d in the vertical direction, the region of the air blown into the furnace 11 and the inner wall surface of the furnace By making the area of the air blown along the upper and lower areas different from each other, it is possible to form an optimum flame swirl flow and to appropriately suppress the high temperature of the furnace wall 11a.

  In the boiler according to the third embodiment, the second nozzles 94a, 94b, 94c, 94d are used as an air injection direction left / right adjustment device that can adjust the injection direction of the additional air from the second nozzles 94a, 94b, 94c, 94d to the left and right. Support shafts 95a, 95b, 95c, and 95d and driving devices 96a, 96b, 96c, and 96d are provided. Therefore, it is possible to properly inject air into a region where corrosion on the inner wall surface of the furnace 11 is likely to occur.

  In the third embodiment, the second nozzles 94a, 94b, 94c, 94d are adjustable in the left-right direction, but the first nozzles 93a, 93b, 93c, 93d may be adjustable in the left-right direction.

[Fourth Embodiment]
FIG. 8 is a plan view of an additional air nozzle in the coal fired boiler according to the fourth embodiment. Note that the basic configuration of the boiler of the present embodiment is substantially the same as that of the first embodiment described above, and will be described with reference to FIG. The same reference numerals are attached and detailed description is omitted.

  In 4th Embodiment, as shown in FIG. 1, the coal burning boiler 10 has the furnace 11 and the combustion apparatus 12, and the combustion apparatus 12 is the some combustion burner 21,22,23,24,25. have. The combustion apparatus 12 includes five combustion burners arranged at equal intervals along the circumferential direction as one set, and five sets along the vertical direction, that is, five stages. Each combustion burner 21, 22, 23, 24, 25 is connected to a pulverized coal machine 31, 32, 33, 34, 35 via a pulverized coal supply pipe 26, 27, 28, 29, 30.

  As shown in FIGS. 1 and 8, the furnace 11 is provided with an additional combustion air supply device 41 above the combustion device 12. The additional combustion air supply device 41 includes additional combustion air nozzles 42 and 43 attached to the furnace wall 11 a, and the end of the first branch air duct 44 branched from the air duct 37 is connected. Yes. The furnace 11 is provided with an additional air supply device 111 above the additional combustion air supply device 41. The additional air supply device 111 has a plurality of additional air nozzles 112 attached to the furnace wall 11 a and is connected to the end of a second branch air duct 53 branched from the air duct 37.

  Here, the additional air supply device 111 will be described in detail. As shown in FIG. 8, the additional air nozzle 112 includes additional air nozzles 112 a, 112 b, 112 c, and 112 d provided at four corners in the furnace 11. Each of the additional air nozzles 112a, 112b, 112c, and 112d is a first nozzle 113a, 113b, 113c, and 113d that blows additional air into the furnace 11 and a first nozzle that blows additional air along one inner wall surface of the furnace 11. 2 nozzles 114 a, 114 b, 114 c, 114 d and third nozzles 115 a, 115 b, 115 c, 115 d for blowing additional air along the other inner wall surface of the furnace 11, and air in three different horizontal directions Can be injected.

  Here, the horizontal blowing angle of the additional air from the first nozzles 113a, 113b, 113c, 113d is the horizontal blowing of the pulverized coal mixture from the combustion burners 21a, 21b, 21c, 21d (see FIG. 2). It is set to the same angle as the angle. On the other hand, the second nozzles 114a, 114b, 114c, 114d can inject additional air in the horizontal direction along one inner wall surface of the furnace wall 11a. The third nozzles 115a, 115b, 115c, and 115d can inject additional air in the horizontal direction along the other inner wall surface of the furnace wall 11a. Each additional air nozzle 112a, 112b, 112c, 112d is connected to each branch pipe 53a, 53b, 53c, 44d branched from the second branch air duct 53.

  Therefore, the additional air can be supplied from the second branch air duct 53 to the additional air nozzles 112a, 112b, 112c, and 112d via the branch pipes 53a, 53b, 53c, and 53d. The first nozzles 113a, 113b, 113c, 113d can inject the air flow A1, A2, A3, A4, and the second nozzles 114a, 114b, 114c, 114d are one inner wall surface of the furnace wall 11a. The third nozzles 115a, 115b, 115c, 115d can inject the airflows A12, A12, A13, A14 along the other inner wall surface of the furnace wall 11a. A24 can be injected.

  As shown in FIGS. 1 and 8, the combustion burners 21, 22, 23, 24, and 25 are provided with pulverized fuel mixture (fuel gas) in which pulverized coal and carrier air are mixed, and secondary air in the furnace 11. A flame swirl can be formed by blowing toward Further, the additional combustion air nozzles 42, 43 can blow additional combustion air into the furnace 11 above the combustion burners 21, 22, 23, 24, 25. Further, the additional air nozzle 112 can blow additional air into the furnace 11 above the combustion burners 21, 22, 23, 24, 25.

  Here, in the additional air nozzle 112, the second nozzles 114a, 114b, 114c, and 114d and the third nozzles 115a, 115b, 115c, and 115d blow additional air along the inner wall surface of the furnace wall 11a in the reduction region B. Since this additional air is blown outward from the flame swirl flow, the flame does not directly contact the inner wall surface of the furnace wall 11a, and the occurrence of corrosion is suppressed by lowering the temperature of the furnace wall 11a.

  Thus, in the boiler according to the fourth embodiment, the first nozzles 113a, 113b, 113c, 113d for blowing additional air into the furnace 11 above the combustion burners 21, 22, 23, 24, 25; Second nozzles 114a, 114b, 114c, 114d for blowing additional air along one inner wall surface of the furnace 11, and third nozzles 115a, 115b, 115c, 115d for blowing additional air along the other inner wall surface of the furnace 11. An additional air nozzle 112 is provided.

  Accordingly, the second nozzles 114a, 114b, 114c, 114d and the third nozzles 115a, 115b, 115c, 115d of the additional air nozzle 112 blow air along the inner wall surface of the furnace wall 11a, so that the combustion gas and the furnace wall 11a are blown. The direct contact with the inner wall surface of the furnace can be suppressed, corrosion of the furnace wall can be prevented, and durability can be improved. Moreover, the high temperature of the furnace wall 11a can be suppressed appropriately by blowing air along all the inner wall surfaces in the furnace wall 11a.

[Fifth Embodiment]
FIG. 9 is a plan view of an additional combustion air nozzle in the coal fired boiler according to the fifth embodiment. Note that the basic configuration of the boiler of the present embodiment is substantially the same as that of the first embodiment described above, and will be described with reference to FIG. The same reference numerals are attached and detailed description is omitted.

  In 5th Embodiment, as shown in FIG. 1, the coal burning boiler 10 has the furnace 11 and the combustion apparatus 12, and the combustion apparatus 12 is the some combustion burner 21,22,23,24,25. have. The combustion apparatus 12 includes five combustion burners arranged at equal intervals along the circumferential direction as one set, and five sets along the vertical direction, that is, five stages. Each combustion burner 21, 22, 23, 24, 25 is connected to a pulverized coal machine 31, 32, 33, 34, 35 via a pulverized coal supply pipe 26, 27, 28, 29, 30.

  As shown in FIGS. 1 and 9, the furnace 11 is provided with an additional combustion air supply device 41 above the combustion device 12. The additional combustion air supply device 41 includes additional combustion air nozzles 42 and 43 attached to the furnace wall 11 a, and the end of the first branch air duct 44 branched from the air duct 37 is connected. Yes. The furnace 11 is provided with an additional air supply device 121 above the additional combustion air supply device 41. This additional air supply device 121 has a plurality of additional air nozzles 82 mounted on the furnace wall 11 a, and the end of the second branch air duct 53 branched from the air duct 37 is connected.

  Here, the additional air supply device 121 will be described in detail. As shown in FIG. 9, the additional air nozzle 82 includes additional air nozzles 82 a, 82 b, 82 c, and 82 d provided at four corners in the furnace 11. Each additional air nozzle 82a, 82b, 82c, 82d includes a first nozzle 83a, 83b, 83c, 83d that blows additional air into the furnace 11, and a second nozzle that blows additional air along the inner wall surface of the furnace 11. 84a, 84b, 84c, 84d.

  Further, the additional air nozzle 82 is provided with a blower that increases the flow rate of the additional air ejected by the first nozzles 83a, 83b, 83c, 83d and the second nozzles 84a, 84b, 84c, 84d. That is, the first nozzles 83a, 83b, 83c, and 83d are connected to the branch pipes 53a, 53b, 53c, and 53d through the pipes 85a, 85b, 85c, and 85d, and the fan 123a is connected to the pipes 85a, 85b, 85c, and 85d. , 123b, 123c, and 123d are provided. On the other hand, the second nozzles 84a, 84b, 84c, 84d are connected to the branch pipes 53a, 53b, 53c, 53d via the pipes 87a, 87b, 87c, 87d, and the fan 124a is connected to the pipes 87a, 87b, 87c, 87d. , 124b, 124c, and 124d are provided.

  Therefore, the air can be supplied from the second branch air duct 53 to the additional air nozzles 82a, 82b, 82c, and 82d via the branch pipes 44a, 44b, 44c, and 44d. The first nozzles 83a, 83b, 83c, 83d can inject the airflows A1, A2, A3, A4, and the second nozzles 84a, 84b, 84c, 84d are along the inner wall surface of the furnace wall 11a. Thus, the air flows A11, A12, A13, A14 can be injected. Further, by changing the rotational speed of the fans 123a, 123b, 123c, 123d and the fans 124a, 124b, 124c, 124d, the first nozzles 83a, 83b, 83c, 83d and the second nozzles 84a, 84b, 84c, 84d can be changed. The injection flow rate of the additional air can be adjusted.

  As shown in FIGS. 1 and 9, the combustion burners 21, 22, 23, 24, and 25 are provided with pulverized fuel mixture (fuel gas) in which the pulverized coal and the carrier air are mixed and the secondary air in the furnace 11. A flame swirl can be formed by blowing toward The additional combustion air nozzle 42 can blow additional combustion air into the furnace 11 above the combustion burners 21, 22, 23, 24, 25. Further, the additional air nozzle 82 can blow additional air into the furnace 11 above the combustion burners 21, 22, 23, 24, 25.

  Here, the additional air nozzle 82 blows in additional air along the inner wall surface of the furnace wall 11a in which the second nozzles 84a, 84b, 84c, and 84d are in the reduction region B. Since this additional air is blown outward from the flame swirl flow, the flame does not directly contact the inner wall surface of the furnace wall 11a, and the occurrence of corrosion is suppressed by lowering the temperature of the furnace wall 11a.

  As described above, the boiler according to the fifth embodiment is additionally provided with the first nozzles 83a, 83b, 83c, 83d for blowing additional air into the furnace 11 above the combustion burners 21, 22, 23, 24, 25. An additional air nozzle 82 having second nozzles 84a, 84b, 84c, 84d for blowing air along the inner wall surface of the furnace 11 is provided, and the first nozzles 83a, 83b, 83c, 83d and the second nozzles 84a, 84b, Fans 123 a, 123 b, 123 c, 123 d and fans 124 a, 124 b, 124 c, 124 d are provided to increase the flow rate of the additional air injected by 84 c, 84 d.

  Therefore, the second nozzles 84a, 84b, 84c, 84d of the additional air nozzle 82 blows air along the inner wall surface of the furnace wall 11a, thereby suppressing direct contact between the combustion gas and the inner wall surface of the furnace wall 11a. As a result, corrosion of the furnace wall can be prevented and durability can be improved. Further, the fan 123a, 123b, 123c, 123d and the fan 124a, 124b, 124c, 124d increase the flow rate of the additional air ejected by the first nozzle 83a, 83b, 83c, 83d and the second nozzle 84a, 84b, 84c, 84d. By doing so, it is possible to effectively suppress the temperature rise of the furnace wall 11a by spreading more air on the inner wall surface of the furnace wall 11a.

[Sixth Embodiment]
FIG. 10 is a schematic configuration diagram illustrating a coal fired boiler according to a sixth 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 6th Embodiment, as shown in FIG. 10, the coal burning boiler 10 has the furnace 11 and the combustion apparatus 12. As shown in FIG. The combustion device 12 has a plurality of combustion burners 21, 22, 23, 24, 25 mounted on the furnace wall. Each combustion burner 21, 22, 23, 24, 25 is connected to a pulverized coal machine 31, 32, 33, 34, 35 via a pulverized coal supply pipe 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 an air duct 37 is connected to the wind box 36.

  The furnace 11 is provided with an additional combustion air supply device 41 at the upper stage of the combustion device 12. The additional combustion air supply device 41 has a plurality of additional combustion air nozzles 42 and 43 attached to the furnace wall. The additional combustion air nozzles 42 and 43 are connected to the ends of the first branch air duct 44 branched from the air duct 37.

  The furnace 11 is provided with an additional air supply device 131 above the combustion device 12. The additional air supply device 131 has a plurality of additional air nozzles 52 mounted on the furnace wall. The additional air nozzle 52 is attached to the wind box 132, and the end of the second branch air duct 53 branched from the air duct 37 is connected to the wind box 132. Further, the additional air nozzle 52 can blow at least a part of the exhaust gas discharged from the furnace 11 into the furnace 11. That is, the end of the third branch air duct 133 branched from the exhaust system 80 continuing to the exhaust gas pipe 78 is connected to the wind box 132, and the blower 134 is provided in the third branch air duct 133.

  Therefore, the combustion burners 21, 22, 23, 24, and 25 blow fine powder fuel mixture and secondary air into the furnace 11 and ignite at this time to form a flame swirl flow in the combustion region A. At this time, the additional combustion air nozzles 42 and 43 appropriately form the combustion region A by blowing the mixture of additional combustion air and exhaust gas into the furnace 11. In the furnace 11, when the pulverized fuel mixture, the secondary air, and the additional combustion air are burned to generate a flame swirl, and a flame swirl is generated in the combustion region A, the combustion gas (exhaust gas) swirls in the furnace 11. It rises while reaching the reduction region B.

  At this time, in the furnace 11, the combustion burners 21, 22, 23, 24, and 25 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 A 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 (first nozzle) blows additional air above the reduction region B of the furnace 11. Then, in the combustion completion region C, the exhaust gas reacts with the additional air, whereby the oxidative combustion of the pulverized coal is completed, and the amount of NOx generated by the combustion of the pulverized coal is reduced.

  Further, in the furnace 11, the additional air nozzle 52 (second nozzle) blows in an air-fuel mixture of additional air and exhaust gas along the inner wall surface of the furnace wall 11 a in the reduction region B. Since this additional air / exhaust gas mixture is blown to the outside of the flame swirl flow, the flame does not directly contact the inner wall surface of the furnace wall 11a, and the occurrence of corrosion is suppressed by lowering the temperature of the furnace wall 11a. The

  As described above, in the boiler according to the sixth embodiment, the additional air nozzle 52 for blowing additional air into the furnace 11 is provided at the upper stage of the combustion burners 21, 22, 23, 24, 25. Can blow at least part of the exhaust gas discharged from the furnace 11 into the furnace 11.

  Accordingly, the air and exhaust gas mixture is blown horizontally along the inner wall surface of the furnace 11 from the additional air supply nozzle 52, thereby suppressing direct contact between the combustion gas and the inner wall surface of the furnace wall 11a. It is possible to improve the durability by preventing the corrosion of 11a. Further, the additional air supply nozzle 52 can suppress an increase in the temperature of the inner wall surface of the furnace 11 by mixing exhaust gas with air and supplying it to the furnace 11.

  In the present embodiment, the additional air supply nozzle 52 blows an air-fuel mixture in which exhaust gas is mixed with air into the furnace 11, but only exhaust gas may be blown into the furnace 11.

  In the above-described embodiment, the form of the combustion burner is the CCF combustion system, but it may be a CUF (Circular Ultra Firing) combustion system.

  In the above-described embodiment, the boiler of the present invention is a coal-fired boiler. However, the fuel may be a boiler using biomass or petroleum coke, or may be applied to an oil-fired boiler.

DESCRIPTION OF SYMBOLS 10 Coal-fired boiler 11 Furnace 12 Combustion device 21, 22, 23, 24, 25 Combustion burner 26, 27, 28, 29, 30 Pulverized coal supply pipe 31, 32, 33, 34, 35 Pulverized coal machine 36 Wind box 37 Air Duct 41 Additional combustion air supply device 42, 43 Additional combustion air nozzle 44 First branch air duct 51, 81, 91, 111, 121, 131 Additional air supply device 52, 82, 92, 112 Additional air nozzle 53 Second Branch air ducts 54a, 54b, 54c, 54d, 83a, 83b, 83c, 83d, 93a, 93b, 93c, 93d, 113a, 113b, 113c, 113d First nozzles 55a, 55b, 55c, 55d, 84a, 84b, 84c 84d, 94a, 94b, 94c, 94d, 114a, 114b, 114c, 114d Second nozzle 86a, 86b, 86c, 86d, 88a, 88b, 88c, 88d damper (air injection amount adjusting device)
90a, 90b, 90c, 90d Drive device (air injection direction vertical adjustment device)
96a, 96b, 96c, 96d Driving device (air injection direction left / right adjusting device)
115a, 115b, 115c, 115d Third nozzle 123a, 123b, 123c, 123d, 124a, 124b, 124c, 124d Fan (blower)

Claims (10)

A furnace that is hollow and installed along the vertical direction;
A combustion burner capable of forming a flame swirl by blowing a fuel gas mixed with solid fuel and combustion air into the furnace;
An additional combustion air nozzle that blows additional combustion air into the furnace above the combustion burner;
An additional air nozzle having a first nozzle that blows additional air into the furnace above the additional combustion air nozzle and a second nozzle that blows additional air along the inner wall surface of the furnace;
The boiler characterized by having.   The boiler according to claim 1, wherein the furnace has a rectangular cross-sectional shape, and the additional air nozzle is disposed at a corner of the furnace.   The combustion burner is disposed at a corner of the furnace, and the additional air nozzle is disposed at a corner above the combustion burner in the furnace, and a blowing angle of fuel gas from the combustion burner in a horizontal direction; The boiler according to claim 2, wherein a horizontal blowing angle of the additional air from the first nozzle is set to be substantially the same angle.   The air injection amount adjusting device for adjusting a ratio between an injection amount of the additional air from the first nozzle and an injection amount of the additional air from the second nozzle is provided. The boiler as described in any one.   The boiler according to any one of claims 1 to 4, wherein the first nozzle and the second nozzle are arranged to be shifted in a vertical direction.   The boiler according to any one of claims 1 to 5, further comprising an air injection direction up / down adjustment device capable of adjusting an injection direction of at least the additional air from the second nozzle up and down.   The boiler according to any one of claims 1 to 6, further comprising an air injection direction left / right adjustment device capable of adjusting at least the injection direction of the additional air from the second nozzle to the left and right.   The said additional air nozzle has a 3rd nozzle which blows in additional air along the inner wall surface different from the said 2nd nozzle in the said furnace, The Claim 1 characterized by the above-mentioned. boiler.   The boiler according to any one of claims 1 to 8, further comprising a blower that increases a flow rate of additional air ejected by the second nozzle.   The boiler according to any one of claims 1 to 8, wherein the additional air nozzle is capable of blowing at least a part of exhaust gas discharged from the furnace into the furnace.

Images