JP6289343B2 - boiler - Google Patents

Description

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

  Conventional coal-fired boilers have a hollow furnace that is installed in the vertical direction, and a plurality of combustion burners are arranged along the circumferential direction on the furnace wall, and arranged in multiple stages in the vertical direction. Has been. The combustion burner is supplied with an air-fuel mixture of pulverized coal (fuel) obtained by pulverizing coal and primary air, and also supplied with high-temperature secondary air, and blows the air-fuel mixture and secondary air into the furnace. This forms a flame and can be burned in this 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, the combustion burner forms a flame by blowing an air-fuel mixture of pulverized coal and air supplied from a pulverizer into the furnace. This pulverized coal is produced by pulverizing coal, but the slagging property (ash melting point) varies depending on the type. In particular, when coal with high slagging properties (low ash melting point) is used, molten ash adheres to the tip of the combustion burner and the inner wall of the furnace, resulting in poor heat transfer performance, furnace damage due to the fall of large clinker, Problems such as blockage of the nozzle portion in the combustion burner will occur.

  As what solves such a problem, there exists a thing described in the following patent document 1, for example. The boiler described in Patent Document 1 is directed to an upper first combustion burner that forms a flame by injecting a first fuel gas mixed with low slugging solid fuel and air into the furnace, and toward the furnace. A lower second combustion burner for forming a flame by injecting a second fuel gas obtained by mixing a highly slugging solid fuel and air is provided.

JP 2014-095540 A

  In the boiler described above, the first fuel gas with low slagging property is injected into the upper stage side of the furnace and the second fuel gas with high slagging property is injected into the lower stage side of the furnace. The 1st fuel gas is supplied and generation | occurrence | production of the slugging in the front-end | tip part of a combustion burner or a furnace wall can be suppressed.

  However, the molten ash caused by the low slagging first fuel gas burned in the upper stage and the molten ash caused by the high slagging second fuel gas burned on the lower stage rise as a result in the furnace. To do. For this reason, the molten ash with high slagging property is taken as the starting point, and the molten ash with low slagging property is taken in, and there is a possibility that ash adhesion to the tip of the combustion burner or the furnace wall occurs.

  This invention solves the subject mentioned above, and it aims at providing the boiler which can suppress generation | occurrence | production of slugging.

  In order to achieve the above object, a boiler according to the present invention includes a furnace having a hollow shape and installed in a vertical direction, and a first fuel gas in which high ash melting point fuel and combustion air are mixed in the furnace. The first flame swirl flow is formed by blowing the first fuel burner that forms the first flame swirl flow by blowing toward the furnace and the second fuel gas mixed with the low ash melting point fuel and the combustion air toward the furnace. And a second combustion burner that forms a second flame swirl flow having a different swirl diameter.

  Therefore, the first combustion burner forms the first flame swirl by blowing the first fuel gas containing the high ash melting point fuel into the furnace, and the second combustion burner is the second combustion burner containing the low ash melting point fuel. A second flame swirl is formed by blowing fuel gas into the furnace. At this time, since the swirl diameters of the first flame swirl flow and the second flame swirl flow are different, the combustion region of the high ash melting point fuel and the combustion region of the low ash melting point fuel are shifted in the radial direction of the flame swirl flow. . Therefore, the ash of the high ash melting point fuel is less likely to be taken into the ash of the low ash melting point fuel, and by suppressing the growth of the ash, the occurrence of slagging at the tip of the combustion burner and the furnace wall can be suppressed.

  In the boiler according to the present invention, the swirl diameter of the second flame swirl flow is set smaller than the swirl diameter of the first flame swirl flow.

  Therefore, the combustion region of the low ash melting point fuel is formed inside the combustion region of the high ash melting point fuel, the ash generated by the combustion of the low ash melting point fuel is separated from the furnace wall, and slagging in the furnace wall Can be suppressed.

  In the boiler according to the present invention, the second combustion burner blows fuel gas toward the center side of the furnace from the first combustion burner.

  Accordingly, the combustion region of the low ash melting point fuel can be easily formed inside the combustion region of the high ash melting point fuel with a simple configuration, and the ash generated by the combustion of the low ash melting point fuel adheres to the furnace wall. Can be suppressed.

  In the boiler according to the present invention, the furnace has a rectangular tube shape, and the first combustion burner is disposed closer to the corner of the furnace than the second combustion burner.

  Therefore, by making the structures of the first and second combustion burners the same and making the arrangement positions different, the combustion region of the low ash melting point fuel can be easily formed inside the combustion region of the high ash melting point fuel.

  The boiler according to the present invention is characterized in that the first combustion burner is disposed above the second combustion burner.

  Therefore, considering the vertical heat flux distribution in the furnace, the heat flux is high on the upper side, and slagging is likely to occur. Therefore, the first flame flow is formed by blowing the high ash melting point fuel on the upper side, and the second flame flow is formed by blowing the low ash melting point fuel on the lower side. Therefore, fuels having different slagging properties are burned at a position commensurate with the slagging properties, and ash adhesion to the tip of the combustion burner and the furnace wall can be suppressed.

  In the boiler according to the present invention, the second combustion burner is arranged above the first combustion burner.

  Therefore, when the amount of high ash melting point fuel injected is greater than the amount of low ash melting point fuel injected, if the low ash melting point fuel is injected upward and the high ash melting point fuel is injected downward, the high ash melting point fuel The combustion time can be ensured for a long time, and the combustibility can be improved.

  In the boiler according to the present invention, when a plurality of at least one of the first combustion burner and the second combustion burner are provided, the first combustion burner and the second combustion burner are alternately arranged in the vertical direction. Yes.

  Accordingly, the combustion region of the high ash melting point fuel and the combustion region of the low ash melting point fuel are alternately formed in the vertical direction, and when a fuel that is difficult to burn is included, the combustibility can be improved.

  The boiler according to the present invention is characterized in that an adjusting device is provided for adjusting a fuel gas blowing direction of the first combustion burner and the second combustion burner in a horizontal direction.

  Therefore, it is only necessary to adjust the direction in which the fuel gas is blown by each combustion burner according to the fuel type and mixing ratio, and the structure of the first and second combustion burners is the same, thereby reducing the manufacturing cost. can do.

  According to the boiler of the present invention, the first fuel swirling flow formed by blowing the first fuel gas containing the high ash melting point fuel into the furnace and the second fuel gas containing the low ash melting point fuel into the furnace. Since the swirl diameter is different from the swirl flow of the second flame formed by blowing toward the ash, the ash of the high ash melting point fuel becomes difficult to be taken into the ash of the low ash melting point fuel, and combustion is suppressed by suppressing the ash growth. The occurrence of slugging at the tip of the burner and the furnace wall can be suppressed.

Drawing 1 is a schematic structure figure showing a coal burning boiler of a 1st embodiment. FIG. 2 is a plan view of the first combustion burner. FIG. 3 is a plan view of the second combustion burner. FIG. 4 is a plan view illustrating a modification of the second combustion burner. FIG. 5 is a schematic diagram showing a flame swirl flow in the furnace. FIG. 6 is a schematic configuration diagram illustrating a coal fired boiler according to the second embodiment. FIG. 7 is a schematic diagram showing a flame swirl flow in the furnace. FIG. 8 is a schematic configuration diagram illustrating a coal fired boiler according to the third embodiment. FIG. 9 is a plan view of the combustion burner.

  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 showing a coal fired boiler according to the first embodiment, FIG. 2 is a plan view of a first combustion burner, FIG. 3 is a plan view of a second combustion burner, and FIG. 4 is a second combustion burner. FIG. 5 is a schematic view showing a flame swirl flow in the furnace.

  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 the first embodiment, as shown in FIG. 1, the coal-fired boiler 10 is a conventional boiler, and includes a furnace 11 and a combustion device 12. The furnace 11 has a rectangular hollow shape and is installed along the vertical direction. The furnace wall constituting the furnace 11 is constituted by a heat transfer tube.

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

  The first combustion burners 21 and 22 arranged on the upper side are connected to pulverized coal machines (mills) 31 and 32 via pulverized coal supply pipes 26 and 27. Although not shown, the pulverized coal machines 31 and 32 are supported in a housing so that the pulverization table can be driven to rotate with a rotation axis along the vertical direction, and a plurality of pulverization rollers rotate above the pulverization table. It is configured to be rotatably supported in conjunction with. 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 to the first combustion burners 21 and 22.

  The second combustion burners 23, 24, 25 arranged on the lower side are connected to pulverized coal machines (mills) 33, 34, 35 via pulverized coal supply pipes 28, 29, 30. Although not shown, the pulverized coal machines 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 a plurality of pulverization rollers are provided above the pulverization table. It is configured to be supported so as to be rotatable in conjunction with the rotation. Therefore, when coal is introduced between a plurality of crushing rollers and a crushing table, the pulverized coal supply pipes 28, 29, and 30 are crushed to a predetermined size and classified by transporting air (primary air). To the second combustion burners 23, 24, 25.

  In the furnace 11, a wind box 36 is provided at the mounting position of each combustion burner 21, 22, 23, 24, 25, and one end of an air duct 37 is connected to the wind box 36. The duct 37 has a blower 38 attached to the other end. Further, the furnace 11 is provided with an additional air nozzle 39 above the mounting position of each combustion burner 21, 22, 23, 24, 25. A branched air duct 40 branched from the air duct 37 to the additional air nozzle 39. The ends of are connected. 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. In addition, combustion air (additional air) sent by the blower 38 can be supplied from the branch air duct 40 to the additional air nozzle 39.

  The furnace 11 has a flue 50 connected to the upper portion thereof. Superheaters (superheaters) 51, 52, and 53 for recovering heat of exhaust gas, and reheaters (reheaters) 54 and 55 are connected to the flue 50. , Economizers 56 and 57 are provided, and heat exchange is performed between the exhaust gas generated by the combustion in the furnace 11 and water.

  The flue 50 is connected to a gas duct 58 to which exhaust gas that has undergone heat exchange is discharged downstream. The gas duct 58 is provided with an air heater 59 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 gas duct 58, and the combustion burners 21, 22, 23, 24, The temperature of the combustion air supplied to 25 can be raised.

  Although not shown, the gas duct 58 is provided with a denitration device, an electrostatic precipitator, an induction blower, and a desulfurization device, and a chimney is provided at the downstream end.

  By the way, each combustion burner 21, 22, 23, 24, 25 forms a flame by injecting pulverized fuel, which is a mixture of pulverized coal and air, into the furnace 11, but the slagging property depends on the type of coal used. That is, when the melting temperature (ash melting point) of ash is different and coal with a low ash melting point is used, the molten ash adheres to the tip of each combustion burner 21, 22, 23, 24, 25 or the inner wall surface of the furnace 11. It becomes easy to do.

  Therefore, in the first embodiment, the first combustion burners 21 and 22 use the first pulverized coal mixture (first fuel gas) obtained by mixing high ash melting point pulverized coal (high ash melting point fuel) and combustion air in the furnace 11. A second flame burner 23, 24, 25 is a second pulverized coal mixture in which low ash melting point pulverized coal (low ash melting point fuel) and combustion air are mixed ( The second fuel gas) is blown into the furnace 11 to form a second flame swirl flow having a swirl diameter different from that of the first flame swirl flow. Specifically, the swirl diameter of the second flame swirl flow is set to be smaller than the swirl diameter of the first flame swirl flow.

  Therefore, the second combustion burners 23, 24, and 25 blow the pulverized coal mixture toward the center side of the furnace 11 from the first combustion burners 21 and 22. In this case, the first combustion burners 21 and 22 are disposed closer to the corners of the furnace 11 than the second combustion burners 23, 24, and 25. Further, the first combustion burners 21 and 22 are arranged above the second combustion burners 23, 24 and 25.

  Here, the combustion device 12 will be described in detail. The first combustion burners 21, 22 and the second combustion burners 23, 24, 25 constituting the combustion device 12 have substantially the same configuration. The first combustion burner 21 and the second combustion burner 23 will be described as a representative.

  As shown in FIG. 2, the first combustion burner 21 (22) is composed of combustion burners 21 a, 21 b, 21 c, and 21 d provided on four wall portions in the furnace 11. Each combustion burner 21a, 21b, 21c, 21d is connected to each branch pipe 26a, 26b, 26c, 26d branched from the pulverized coal supply pipe 26, and each branch pipe 37a, 37b, 37c branched from the air duct 37. , 37d are connected.

  Moreover, the 2nd combustion burner 23 (24, 25) is comprised from the combustion burner 23a, 23b, 23c, 23d each provided in the four wall parts in the furnace 11, as shown in FIG. Each combustion burner 23a, 23b, 23c, 23d is connected to each branch pipe 28a, 28b, 28c, 28d branched from the pulverized coal supply pipe 28, and each branch pipe 37a, 37b, 37c branched from the air duct 37. , 37d are connected.

  Here, as shown in FIG.2 and FIG.3, the 1st combustion burners 21a, 21b, 21c, and 21d are arrange | positioned rather than the 2nd combustion burners 23a, 23b, 23c, and 23d at the corner | angular part side of the furnace 11. FIG. In other words, the second combustion burners 23a, 23b, 23c, and 23d are arranged closer to the center O (center line L) side of the furnace 11 than the first combustion burners 21a, 21b, 21c, and 21d.

  Therefore, in the first combustion burner 21, each combustion burner 21a, 21b, 21c, 21d blows the first pulverized coal mixture in which the high ash melting point pulverized coal and the carrier air are mixed into the furnace 11, Combustion air is blown outside the first pulverized coal mixture. And by igniting this 1st pulverized coal mixture, four flames F1, F2, F3, and F4 can be formed, and this flame F1, F2, F3, and F4 are seen from the upper side of the furnace 11. A first flame swirl flow C1 swirling counterclockwise (in FIG. 2) is obtained. Moreover, in the 2nd combustion burner 23, each combustion burner 23a, 23b, 23c, 23d blows into the furnace 11 the 2nd pulverized coal mixture which the low ash melting | fusing point pulverized coal and the carrier air mixed, Combustion air is blown outside the second pulverized coal mixture. Then, by igniting the second pulverized coal mixture, four flames F11, F12, F13, and F14 can be formed. The flames F11, F12, F13, and F14 are viewed from above the furnace 11. A second flame swirl flow C2 swirling counterclockwise (in FIG. 3) is obtained.

  Here, the second pulverized coal mixture from the second combustion burners 23a, 23b, 23c, and 23d is closer to the center O side of the furnace 11 than the first pulverized coal mixture of the first combustion burners 21a, 21b, 21c, and 21d. Blow toward. Therefore, the swirl diameter of the second flame swirl flow C2 is smaller than the swirl diameter of the first flame swirl flow C1.

  A high ash melting point fuel having low slagging property is defined as a fuel having an ash melting temperature (ash melting point) of 1200 ° C. or higher, and a low ash melting point fuel having high slagging property is defined as an ash melting temperature (ash melting point). The melting point) is defined as a fuel lower than 1200 degrees. In the first embodiment, bituminous coal pulverized fuel is used as the low slagging solid fuel, and subbituminous coal pulverized fuel is used as the high slagging solid fuel. However, the type of fuel to be applied is not limited to this bituminous coal or subbituminous coal. For example, high ash melting point fuels having low slagging properties include anthracite and semi-anthracite in addition to bituminous coal. On the other hand, the low ash melting point fuel having high slagging property includes lignite, lignite, peat, coke, biomass, etc. with high moisture and oxygen in addition to subbituminous coal.

  In the first embodiment, the use ratio of the first combustion burner and the second combustion burner according to the mixing ratio of the high ash melting point fuel having low slagging property and the low ash melting point fuel having high slagging property in the coal used. Is set. In this embodiment, the ratio of the high ash melting point fuel having low slagging property in the coal used is 40%, and the ratio of the low ash melting point fuel having high slagging property is 60%. Therefore, the upper first combustion burners 21 and 22 are used for high ash melting point fuel having low slagging property, and the lower second combustion burners 23, 24, and 25 are used for low ash melting point fuel having high slagging property. use.

  In this embodiment, the first combustion burners 21a, 21b, 21c, and 21d are arranged closer to the corners of the furnace 11 than the second combustion burners 23a, 23b, 23c, and 23d. Although the swirl diameter of the second flame swirl flow C2 is made smaller than the swirl diameter, it is not limited to this configuration.

  For example, as shown in FIG. 4, the second combustion burner 23 is configured by arranging combustion burners 23 a, 23 b, 23 c, and 23 d at the same positions as the first combustion burner 21. Each combustion burner 23a, 23b, 23c, 23d is connected to each branch pipe 28a, 28b, 28c, 28d branched from the pulverized coal supply pipe 28, and each branch pipe 37a, 37b, 37c branched from the air duct 37. , 37d are connected. The combustion burners 23a, 23b, 23c, and 23d are set such that the second fuel gas blowing direction is closer to the center O side of the furnace 11 than the first fuel gas blowing direction by the combustion burners 21a, 21b, 21c, and 21d. Has been. That is, the blowing direction of the first pulverized coal mixture by the first combustion burners 21a, 21b, 21c, 21d is parallel to the adjacent wall portion of the furnace 11, but the second combustion burners 23a, 23b, 23c, 23d. The direction in which the second pulverized coal mixture is blown is set to an angle of, for example, 20 degrees with respect to the adjacent wall portion of the furnace 11.

  Therefore, each combustion burner 23a, 23b, 23c, 23d blows into the furnace 11 the second pulverized coal mixture in which the low ash melting point pulverized coal and the carrier air are mixed, and the second pulverized coal mixture Blow combustion air to the outside. And by igniting this 2nd pulverized coal mixture, four flames F11, F12, F13, and F14 can be formed, and the 2nd flame swirl flow C2 can be formed. In this case, the swirl diameter of the second flame swirl flow C2 is smaller than the swirl diameter of the first flame swirl flow C1.

  In the coal-fired boiler 10 of this embodiment configured as described above, when the pulverized coal machines 31, 32, 33, 34, and 35 are driven as shown in FIG. 1, the pulverized coal machines 31 and 32 have a high ash melting point. The solid fuel is pulverized, and the high ash melting point pulverized coal is supplied to the first combustion burners 21 and 22 from the pulverized coal supply pipes 26 and 27 together with the air for conveyance. The pulverized coal machines 33, 34, and 35 pulverize the low ash melting point solid fuel, and the generated low ash melting point pulverized coal together with the air for conveyance from the pulverized coal supply pipes 28, 29, 30 to the second combustion burner 23. , 24, 25.

  The heated combustion air is supplied from the air duct 37 to the combustion burners 21, 22, 23, 24, 25 via the wind box 36, and is supplied from the branch air duct 40 to the additional air nozzle 39. . Then, the combustion burners 21, 22, 23, 24, and 25 blow a pulverized coal mixture, which is a mixture of pulverized coal and carrier air, into the furnace 11 and blow combustion air into the furnace 11 and ignite at this time. Can form a flame. Further, the additional air nozzle 39 can perform combustion control by blowing additional air into the furnace 11. In the furnace 11, the pulverized coal mixture and the combustion air are burned to generate a flame. When a flame is generated in the lower part of the furnace 11, the combustion gas (exhaust gas) rises in the furnace 11, and the flue 50 is discharged.

  At this time, as shown in FIG. 5, the first combustion burners 21, 22 bring the first pulverized coal mixture and the combustion air into which the high ash melting point pulverized coal and the carrier air are mixed into the combustion region A of the furnace 11. By blowing and igniting at this time, a first flame swirl flow C1 is formed in the combustion region A. On the other hand, the second combustion burners 23, 24, and 25 blow the second pulverized coal mixture and the combustion air, which are a mixture of the low ash melting point pulverized coal and the carrier air, into the combustion region A of the furnace 11, and ignite at this time. As a result, a second flame swirl flow C2 is formed in the combustion region A. Further, the additional air nozzle 39 blows additional air above the reduction region B in the furnace 11 to perform combustion control. In the furnace 11, when the first and second pulverized coal mixture and the combustion air are burned to generate the first and second flame swirl flows C1 and C2, and the flame swirl flow is generated in the combustion region A, the combustion gas The (exhaust gas) rises while turning and reaches the reduction region B.

  Further, the first combustion burners 21 and 22 blow the first pulverized coal mixture containing the high ash melting point pulverized coal above the combustion region A, thereby forming a first flame swirl flow C1 having a large diameter. The combustion burners 23, 24, and 25 blow the second pulverized coal mixture containing the low ash melting point pulverized coal below the combustion region A to form the second flame swirl flow C2 having a small diameter. Then, since the second flame swirl flow C2 is formed inside the first flame swirl flow C1, the combustion region of the low ash melting point fuel is located inside the combustion region of the high ash melting point fuel. Therefore, the ash of the high ash melting point pulverized coal becomes difficult to be taken into the ash of the low ash melting point pulverized coal, and the growth of the low ash melting point ash is suppressed, so that the tips of the combustion burners 21, 22, 23, 24, 25 Ash adhesion on the wall and furnace wall is suppressed. Moreover, the combustion region of the low ash melting point pulverized coal is located in the center of the furnace 11, and the ash having the low ash melting point rises in the center of the furnace 11. Is done.

  Further, in the furnace 11, the interior is maintained in a reducing atmosphere by setting the air supply amount to be less than the theoretical air amount with respect to the pulverized coal supply amount. The NOx generated by the combustion of the pulverized coal is reduced in the furnace 11, and then additional air (additional air) is additionally supplied to complete the oxidative combustion of the pulverized coal. The amount of NOx generated by the combustion of the pulverized coal Is reduced. That is, in the furnace 11, a combustion region A for reducing NOx is formed between the combustion burner 21 and the additional air nozzle 39.

  The water supplied from a water supply pump (not shown) is preheated by the economizers 56 and 57, and then heated while being supplied to a steam drum (not shown) and supplied to each water pipe (not shown) on the furnace wall. Then, it becomes saturated steam and is sent to a steam drum (not shown). Further, saturated steam of a steam drum (not shown) is introduced into the superheaters 51, 52, and 53 and is heated by the combustion gas. The superheated steam generated by the superheaters 51, 52, 53 is supplied to a power plant (not shown) such as a turbine. Further, the steam taken out in the middle of the expansion process in the turbine is introduced into the reheaters 54 and 55, 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 56 and 57 of the flue 50 is subjected to removal of harmful substances such as NOx by a catalyst in a denitration apparatus (not shown) in a gas duct 58, and particulate matter is removed by an electric dust collector. After the sulfur content is removed by the desulfurization device, it is discharged from the chimney into the atmosphere.

  As described above, in the boiler according to the first embodiment, the furnace 11 installed in the vertical direction with a hollow shape, and the first pulverized coal mixture obtained by mixing the high ash melting point pulverized coal and the combustion air are used. The first combustion burners 21 and 22 that form the first flame swirl flow C <b> 1 by blowing into the furnace 11, and the second pulverized coal mixture in which the low ash melting point pulverized coal and the combustion air are mixed into the furnace 11. The second combustion burners 23, 24, and 25 that form the second flame swirl flow C2 having a swirl diameter different from that of the first flame swirl flow C1 are provided.

  Therefore, since the swirl diameters of the first flame swirl flow C1 and the second flame swirl flow C2 are different, the combustion region of the high ash melting point pulverized coal and the combustion region of the low ash melting point pulverized coal are shifted in the radial direction of the flame swirl flow. It will be. Therefore, the ash of the high ash melting point pulverized coal becomes difficult to be taken into the ash of the low ash melting point pulverized coal, and by suppressing the growth of the ash, the tip of the combustion burners 21, 22, 23, 24, 25 and the furnace wall The occurrence of slugging can be suppressed.

  In the boiler of the first embodiment, the swirl diameter of the second flame swirl flow C2 is set smaller than the swirl diameter of the first flame swirl flow C1. Therefore, the combustion region of the low ash melting point pulverized coal is formed inside the combustion region of the high ash melting point pulverized coal, and the ash generated by the combustion of the low ash melting point pulverized coal will be separated from the furnace wall. Generation of slugging in the wall can be suppressed.

  In the boiler according to the first embodiment, the second combustion burners 23, 24, and 25 blow the second pulverized coal mixture toward the center of the furnace 11 from the first combustion burners 21 and 22. Therefore, the combustion zone of the low ash melting point pulverized coal can be easily formed inside the combustion region of the high ash melting point pulverized coal with a simple configuration, and the ash furnace wall produced by the combustion of the low ash melting point pulverized coal Adhesion to can be suppressed.

  In the boiler according to the first embodiment, the first combustion burners 21 and 22 are arranged closer to the corners of the furnace 11 than the second combustion burners 23, 24, and 25. Therefore, the structure of the first and second combustion burners 21, 22, 23, 24, and 25 is made the same, and the low ash melting point pulverized coal is easily placed inside the combustion region of the high ash melting point pulverized coal simply by changing the arrangement position. The combustion region can be formed.

  In the boiler according to the first embodiment, the first combustion burners 21 and 22 are disposed above the second combustion burners 23, 24 and 25. Considering the heat flux distribution in the vertical direction in the furnace 11, the heat flux is high on the upper side, and slugging is likely to occur. Therefore, the first flame swirl flow C1 is formed by blowing high ash melting point pulverized coal on the upper side, and the second flame swirl flow C2 is formed by blowing low ash melting point pulverized coal on the lower side. Therefore, fuels having different slagging properties are burned at positions (temperatures) commensurate with the slagging properties, and ash adhesion to the tip portions of the combustion burners 21, 22, 23, 24, 25 and the furnace wall can be suppressed. .

[Second Embodiment]
FIG. 6 is a schematic configuration diagram illustrating a coal-fired boiler according to the second embodiment, and FIG. 7 is a schematic diagram illustrating a flame swirl flow in a furnace. 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 2nd Embodiment, as shown in FIG. 6, the coal burning boiler 100 is a conventional boiler, Comprising: The furnace 11 and the combustion apparatus 101 are provided. The combustion apparatus 101 has a plurality of combustion burners 111, 112, 113, 114, 115. Second combustion burners 111 and 112 arranged on the upper side are connected to pulverized coal machines 31 and 32 via pulverized coal supply pipes 26 and 27. The first combustion burners 113, 114, 115 arranged on the lower side are connected to the pulverized coal machines 33, 34, 35 via the pulverized coal supply pipes 28, 29, 30.

  The second combustion burners 111 and 112 form a second flame swirl flow by blowing a second pulverized coal mixture obtained by mixing low ash melting point pulverized coal and combustion air into the furnace 11. The first combustion burners 113, 114, and 115 blow the first pulverized coal mixture, which is a mixture of high ash melting point pulverized coal and combustion air, into the furnace 11, so that the second flame swirl flow and swirl diameter are increased. A different first flame swirl flow is formed. Specifically, the swirl diameter of the second flame swirl flow is set to be smaller than the swirl diameter of the first flame swirl flow.

  Therefore, the second combustion burners 111 and 112 blow the pulverized coal mixture toward the center side of the furnace 11 from the first combustion burners 113, 114, and 115. In this case, the first combustion burners 113, 114, 115 are arranged closer to the corners of the furnace 11 than the second combustion burners 111, 112. Further, the second combustion burners 111 and 112 are disposed above the first combustion burners 113, 114 and 115.

  Therefore, the pulverized coal machines 31 and 32 pulverize the low ash melting point solid fuel, and supply the low ash melting point pulverized coal together with the conveying air from the pulverized coal supply pipes 26 and 27 to the second combustion burners 111 and 112. The pulverized coal machines 33, 34, and 35 pulverize the high ash melting point solid fuel, and the generated high ash melting point pulverized coal together with the conveying air from the pulverized coal supply pipes 28, 29, and 30 to the first combustion burner 113. , 114 and 115.

  Then, the combustion burners 111, 112, 113, 114, and 115 blow the pulverized coal mixture in which the pulverized coal and the carrier air are mixed into the furnace 11 and the combustion air into the furnace 11 and ignite at this time. To form a flame. In the furnace 11, the pulverized coal mixture and the combustion air are burned to generate a flame. When a flame is generated in the lower part of the furnace 11, the combustion gas (exhaust gas) rises in the furnace 11, and the flue 50 is discharged.

  At this time, as shown in FIG. 7, the second combustion burners 111 and 112 feed the second pulverized coal mixture in which the low ash melting point pulverized coal and the carrier air are mixed and the combustion air to the combustion region A of the furnace 11. By blowing and igniting at this time, a second flame swirl flow C2 is formed in the combustion region A. On the other hand, the first combustion burners 113, 114, and 115 blow the first pulverized coal mixture and the combustion air, which are a mixture of the high ash melting point pulverized coal and the carrier air, into the combustion region A of the furnace 11, and ignite at this time. Thus, the first flame swirl flow C1 is formed in the combustion region A. Further, the additional air nozzle 39 blows additional air above the reduction region B in the furnace 11 to perform combustion control. In the furnace 11, when the first and second pulverized coal mixture and the combustion air are burned to generate the first and second flame swirl flows C1 and C2, and the flame swirl flow is generated in the combustion region A, the combustion gas The (exhaust gas) rises while turning and reaches the reduction region B.

  Further, the second combustion burners 111 and 112 blow the second pulverized coal mixture containing the low ash melting point pulverized coal above the combustion region A, thereby forming the second flame swirl flow C2 having a small diameter, and the first combustion. The burners 113, 114, and 115 blow the first pulverized coal mixture containing the high ash melting point pulverized coal below the combustion region A to form a large-diameter first flame swirl flow C1. Then, since the second flame swirl flow C2 is formed inside the first flame swirl flow C1, the combustion region of the low ash melting point fuel is located inside the combustion region of the high ash melting point fuel. Therefore, the ash of the high ash melting point pulverized coal becomes difficult to be taken into the ash of the low ash melting point pulverized coal, and the growth of the low ash melting point ash is suppressed, so that the tips of the combustion burners 111, 112, 113, 114, 115 Ash adhesion on the wall and furnace wall is suppressed. Moreover, the combustion region of the low ash melting point pulverized coal is located in the center of the furnace 11, and the ash having the low ash melting point rises in the center of the furnace 11. Is done.

  As described above, in the boiler according to the second embodiment, the furnace 11 installed in the vertical direction with a hollow shape, and the first pulverized coal mixture in which the high ash melting point pulverized coal and the combustion air are mixed are used. The first combustion burners 113, 114, and 115 that form the first flame swirl flow C1 by blowing into the furnace 11 and the second pulverized coal mixture obtained by mixing the low ash melting point pulverized coal and the combustion air are used as the furnace 11. There are provided second combustion burners 111 and 112 that form a second flame swirl flow C2 having a smaller diameter than the first flame swirl flow C1 by blowing inwardly.

  Therefore, since the swirl diameters of the first flame swirl flow C1 and the second flame swirl flow C2 are different, the combustion region of the high ash melting point pulverized coal and the combustion region of the low ash melting point pulverized coal are shifted in the radial direction of the flame swirl flow. It will be. Therefore, the ash of the high ash melting point pulverized coal becomes difficult to be taken into the ash of the low ash melting point pulverized coal, and by suppressing the growth of the ash, the tip of the combustion burners 111, 112, 113, 114, 115 and the furnace wall The occurrence of slugging can be suppressed.

  In the boiler according to the second embodiment, the second combustion burners 111 and 112 are disposed above the first combustion burners 113, 114, and 115. Accordingly, different slagging fuels are burned at a position (temperature) commensurate with the slagging properties, and ash adhesion to the tip of the combustion burners 111, 112, 113, 114, 115 and the furnace wall can be suppressed. .

  Further, when the amount of high ash melting point pulverized coal is greater than the amount of low ash melting point pulverized coal, the second combustion burners 111 and 112 are disposed on the upper side to inject the low ash melting point pulverized coal and the first side is directed downward. Combustion burners 113, 114, and 115 are arranged to blow high ash melting point pulverized coal. That is, by blowing the high ash melting point pulverized coal with a large amount of blowing from the three second combustion burners 113, 114, 115 below the combustion region A, a long combustion time of the high ash melting point pulverized coal with a large amount of blowing is ensured. It is possible to improve the flammability.

[Third Embodiment]
FIG. 8 is a schematic configuration diagram illustrating a coal fired boiler according to the third embodiment, and FIG. 9 is a plan view of a combustion burner. 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 3rd Embodiment, as shown in FIG. 8, the coal fired boiler 120 is a conventional boiler, Comprising: The furnace 11 and the combustion apparatus 121 are provided. The combustion device 121 has a plurality of combustion burners 131, 132, 133, 134, 135. Here, although the combustion apparatus 121 is demonstrated in detail, since the combustion burners 131, 132, 134, and 135 which comprise this combustion apparatus 121 have comprised the substantially the same structure, the combustion burner 131 is demonstrated on behalf of it. To do.

  As shown in FIG. 9, the combustion burner 131 includes combustion burners 131 a, 131 b, 131 c, and 131 d provided on four wall portions in the furnace 11. Each combustion burner 131a, 131b, 131c, 131d 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. Each combustion burner 131a, 131b, 131c, 131d is provided with an injection direction adjusting device (adjusting device) 141 (141a, 141b, 141c, 141d) that can adjust the injection direction of the pulverized coal mixture in the horizontal direction. Yes. This injection direction adjusting device 141 (141a, 141b, 141c, 141d), for example, swivels the nozzles of the combustion burners 131a, 133b, 133c, 133d left and right by an adjusting motor (not shown), The injection angle can be adjusted.

  As shown in FIG. 8, the other combustion burners 132, 133, 134, 135 are injection direction adjusting devices (adjusting devices) 142, 143, 144, which can adjust the injection direction of the pulverized coal mixture in the horizontal direction. 145 is provided.

  In the third embodiment, as shown in FIGS. 8 and 9, for example, as in the first embodiment, the first combustion burners 131 and 132 are the first pulverized coal in which high ash melting point pulverized coal and combustion air are mixed. A first flame swirl flow C1 is formed by blowing the air-fuel mixture into the furnace 11, and a second pulverized coal mixture in which the second combustion burners 133, 134, and 135 are mixed with low ash melting point pulverized coal and combustion air. Is blown into the furnace 11 to form a second flame swirl flow C2 having a smaller diameter than the first flame swirl flow C1.

  Therefore, the injection direction adjusting devices 141, 142, 143, 144, and 145 adjust the injection angle of the pulverized coal mixture by adjusting the directions of the nozzle portions of the combustion burners 131, 132, 134, and 135 to the left and right. That is, the blowing direction of the first pulverized coal mixture by the first combustion burners 131 and 132 is parallel to the adjacent wall portion, and the blowing direction of the second pulverized coal mixture by the second combustion burners 133, 134, and 135 is adjacent. It sets to a predetermined angle (for example, 20 degrees) with respect to the wall part to do. Therefore, the second combustion burners 133, 134, and 135 are configured to blow the pulverized coal mixture toward the center side of the furnace 11 from the first combustion burners 131 and 132.

  In addition, since the action | operation of the coal burning boiler 120 of this embodiment is substantially the same as 1st Embodiment, description is abbreviate | omitted.

  Thus, in the boiler of 3rd Embodiment, the injection direction adjustment apparatus 141,142,143,144,145 which adjusts the blowing direction of the pulverized coal mixture by the combustion burners 131,132,134,135 to a horizontal direction. Is provided.

  Therefore, if the injection direction adjusting devices 141, 142, 143, 144, and 145 adjust the blowing direction of the pulverized coal mixture by the combustion burners 131, 132, 134, and 135 according to the type of coal and the mixing ratio of the pulverized coal. Good. Therefore, the manufacturing cost can be reduced by setting the structures of all the combustion burners 131, 132, 134, 135 in the same manner.

  In the third embodiment, the first combustion burners 131 and 132 and the second combustion burners 133, 134, and 135 are set as in the first embodiment, but may be set as in the second embodiment. Moreover, what is necessary is just to set the ratio allocated to a 1st combustion burner and a 2nd combustion burner according to the kind of coal, and the mixing ratio of pulverized coal.

  In the above-described embodiment, the first combustion burner (or the second combustion burner) is disposed on the upper side, and the second combustion burner (or the first combustion burner) is disposed on the lower side. It is not limited to. For example, the first combustion burner and the second combustion burner may be alternately arranged in the vertical direction. In this case, the combustion region of the high ash melting point fuel and the combustion region of the low ash melting point fuel are alternately formed in the vertical direction, and when a fuel that is difficult to burn is included, the combustibility can be improved.

  In the above-described embodiment, the first combustion burner is configured to form a large-diameter first flame swirl flow, and the second combustion burner is configured to form a small-diameter second flame swirl flow. May form a first flame swirl flow having a small diameter, and the second combustion burner may form a second flame swirl flow having a large diameter.

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

10, 100, 120 Coal-fired boiler 11 Furnace 12, 101, 121 Combustion device 21, 22, 113, 114, 115, 131, 132 First combustion burner 23, 24, 25, 111, 112, 133, 134, 135 2 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 39 Additional air nozzle 40 Branch air duct 50 Chimney 51, 52, 53 Superheater 54, 55 Reheater 56, 57 Eco-saving device 141, 142, 143, 144, 145 Injection direction adjusting device (adjusting device)

Claims (7)

A furnace that is hollow and installed along the vertical direction;
A first combustion burner for forming a first flame swirl flow by blowing a first fuel gas mixed with a high ash melting point fuel and combustion air into the furnace;
A second combustion burner for forming a second flame swirl flow having a different swirl diameter from the first flame swirl flow by blowing a second fuel gas mixed with low ash melting point fuel and combustion air into the furnace; ,
I have a,
The swirl diameter of the second flame swirl is set smaller than the swirl diameter of the first flame swirl;
A boiler characterized by that. The boiler according to claim 1 , wherein the second combustion burner blows fuel gas toward the center side of the furnace from the first combustion burner. The boiler according to claim 2 , wherein the furnace has a rectangular tube shape, and the first combustion burner is disposed closer to a corner of the furnace than the second combustion burner. The boiler according to any one of claims 1 to 3 , wherein the first combustion burner is disposed above the second combustion burner. The boiler according to any one of claims 1 to 3 , wherein the second combustion burner is disposed above the first combustion burner. When at least one of the second combustion burner and the first combustion burner is plurality, wherein claim 1, wherein the second combustion burner and the first combustion burner is disposed alternately in the vertical direction Item 6. The boiler according to any one of items 5 . The boiler according to any one of claims 1 to 6 , further comprising an adjusting device that adjusts a fuel gas blowing direction of the first combustion burner and the second combustion burner in a horizontal direction.

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