JP2014095540A - Boiler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a boiler capable of suppressing the occurrence of slugging in a combustion burner.SOLUTION: Upper stage combustion burners (first combustion burners) 21, 22 capable of forming flame by blowing-in a first fuel gas made by mixing a low-slugging solid fuel and air toward the interior of a furnace 11, and lower stage combustion burners (second combustion burners) 23, 24, 25 capable of forming flame by blowing-in a second fuel gas made by mixing a high-slugging solid fuel and air toward the interior of the furnace 11 are provided.

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 varies depending on the type. In particular, when coal with high slagging properties is used, molten ash adheres to the tip of the combustion burner and the inner wall of the furnace, heat transfer performance decreases, furnace damage due to the fall of large clinker, nozzle part in the combustion burner Problems such as blockage will occur.

  As what solves such a problem, there exists a thing described in the following patent document 1, for example. The method for suppressing ash adhesion of a coal-fired boiler described in Patent Document 1 is a method in which at least one of silicon dioxide and aluminum oxide in ash is large and alkaline in coal with a small amount of at least one of sulfur and ash and a large amount of alkali components. The fly ash which is combustion ash of coal with few components is mixed, and the mixture of these coal and combustion ash is burned in the furnace of a coal fired boiler.

Japanese Patent No. 3771687 Japanese Patent Laid-Open No. 10-160101

  In general, a coal fired boiler is provided with a plurality of combustion burners in the circumferential direction of the furnace wall and in a plurality of stages in the vertical direction. Therefore, the heat flux distribution in the vertical direction in the furnace is high in the vicinity of the combustion burner on the upper stage side, and a lot of slugging occurs at this position. Therefore, as described above, even if the mixed fuel obtained by mixing the high slagging fuel and the low slagging fuel is burned in the furnace of the boiler, the occurrence of slagging in the upper stage of the furnace cannot be sufficiently prevented.

  In the method for controlling the burner of the coal-fired boiler of Patent Document 2, when the coal to be burned is a low fuel specific coal, the upper stage of the burner nozzles at a plurality of times is used, and in the case of a high fuel specific coal, the lower stage is used. The side burner nozzle is used. However, in this case, the upper burner nozzle injects low fuel specific coal, that is, high slagging fuel, and the occurrence of slagging in the upper stage of the furnace cannot be prevented.

  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 along a vertical direction, and a first fuel obtained by mixing solid fuel and air having low slagging properties into the furnace. A first combustion burner capable of forming a flame by injecting a gas, and a second combustion fuel which is disposed below the first combustion burner in a vertical direction and mixed with a highly slugging solid fuel and air toward the furnace. It has a 2nd combustion burner which can form a flame by blowing in fuel gas, and a heat exchanger which is provided in the upper part of the above-mentioned furnace, and collects internal heat.

  Therefore, when considering the heat flux distribution in the vertical direction in the furnace, it is high in the vicinity of the combustion burner on the upper stage side, and slugging is likely to occur. Therefore, the first combustion burner disposed on the upper stage side blows the first fuel gas having low slagging characteristics toward the furnace, and a flame is formed. The second combustion burner disposed on the lower stage side faces the furnace. Therefore, the second fuel gas having high slagging property is injected. Therefore, the first fuel gas having low slagging property is supplied to a region where the thermal load in the furnace is high, and the occurrence of slagging at the tip of the combustion burner and the furnace wall can be suppressed.

  In the boiler of the present invention, a first fuel pulverizer for pulverizing the low slagging solid fuel to form pulverized fuel is connected to the first combustion burner, and the high slagging solid fuel is connected to the second combustion burner. A second fuel pulverizer that pulverizes and forms a pulverized fuel is connected.

  Therefore, by connecting a dedicated fuel pulverizer capable of supplying a predetermined pulverized fuel for each combustion burner, low slagging pulverized fuel can be easily supplied to the first combustion burner, and the second Highly slagging fine powder fuel can be easily supplied to the combustion burner.

  In the boiler according to the present invention, the furnace is provided with a plurality of combustion burners along a vertical direction, and the first furnace is configured according to a mixing ratio of the low slagging solid fuel and the high slagging solid fuel in the solid fuel to be used. The use ratio of the 1 combustion burner and the second combustion burner is set.

  Therefore, the combustion burner which makes the structure of the 1st combustion burner and the 2nd combustion burner the same, and inject | emits each solid fuel according to the mixing ratio of the low slagging solid fuel and the high slagging solid fuel in the solid fuel to be used. By setting the use ratio of the structure, the structure can be simplified and the cost can be reduced.

  The boiler according to the present invention is characterized in that the first combustion burner is a low slagging fuel combustion burner in which the concentration of the solid fuel is increased in the central portion of the jet of the first fuel gas.

  Therefore, the first fuel gas having a low slagging property is supplied to the region where the heat load in the furnace is high by using the combustion burner for the low slagging property, and slagging is generated at the tip of the combustion burner and the furnace wall. Can be suppressed.

  The boiler according to the present invention is characterized in that a fuel having an ash melting temperature higher than 1200 degrees is used as the low slagging solid fuel.

  Therefore, it is possible to suppress the occurrence of slugging at the tip of the combustion burner and the furnace wall.

  The boiler of the present invention is characterized by using a bituminous coal pulverized fuel as the low slagging solid fuel and using a subbituminous coal pulverized fuel as the high slagging solid fuel.

  Therefore, it is possible to suppress the occurrence of slugging at the tip of the combustion burner and the furnace wall using an inexpensive solid fuel.

  According to the boiler of the present invention, a first combustion burner capable of forming a flame by blowing a first fuel gas in which a low-slagging solid fuel and air are mixed into the furnace, and more vertical than the first combustion burner. Since the second combustion burner which is arranged in the lower direction and can form a flame by injecting a second fuel gas mixed with highly slugging solid fuel and air into the furnace is provided, the tip of the combustion burner Generation of slugging in the furnace wall can be suppressed.

FIG. 1 is a schematic configuration diagram illustrating a coal fired boiler according to a first embodiment of the present invention. FIG. 2 is a plan view of a combustion burner in the coal fired boiler according to the first embodiment. FIG. 3 is a schematic configuration diagram illustrating a coal fired boiler according to a second embodiment of the present invention. FIG. 4 is a schematic diagram illustrating a low slagging combustion burner. FIG. 5 is a schematic diagram illustrating another low slagging combustion burner.

  Exemplary embodiments of a boiler according to the present invention will be described below in detail with reference to the accompanying drawings. In addition, this invention is not limited by this Example, Moreover, when there exists multiple Example, what comprises combining each Example is also included.

  FIG. 1 is a schematic configuration diagram illustrating a coal burning boiler according to a first embodiment of the present invention, and FIG. 2 is a plan view of a combustion burner in the coal burning boiler according to the first embodiment.

  The boiler of Example 1 uses pulverized coal obtained by pulverizing coal (bituminous coal, subbituminous coal, etc.) as a pulverized fuel, burns the pulverized coal with a combustion burner, and recovers the heat generated by the combustion. It is a charcoal fired boiler.

  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 5 sets along the vertical direction. Five stages are arranged. The shape of the furnace, the number of combustion burners in one stage, and the number of stages are not limited to this embodiment.

  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. ing. 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. Therefore, when coal is introduced between a plurality of crushing rollers and a crushing table, the pulverized coal supplied to the pulverized coal supply pipes 26 and 27 is pulverized to a predetermined size and classified by carrier air (primary air). , 28, 29, 30 can be supplied to the combustion burners 21, 22, 23, 24, 25.

  Further, the furnace 11 is provided with a wind box 36 at the 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, and this air 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.

  Therefore, in the combustion apparatus 12, each combustion burner 21, 22, 23, 24, 25 can blow a pulverized fuel mixture (fuel gas) obtained by mixing pulverized coal and primary air into the furnace 11. The additional air can be blown into the furnace 11. Further, the additional air nozzle 39 can blow additional air into the furnace 11. A flame can be formed by igniting the pulverized fuel mixture with an ignition torch (not shown).

  In general, when the boiler is started, each combustion burner 21, 22, 23, 24, 25 injects oil fuel into the furnace 11 to form a flame.

  Further, the form of the combustion burner is not limited to that described above. That is, the attachment position of the combustion burner may be not the corner of the furnace 11 but the wall of the furnace 11. Further, the combustion burner may be a system that forms a flame counterflow instead of a flame swirl flow, or may be provided only on the wall of the furnace 11.

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

  The flue 50 is connected to an exhaust gas pipe 58 from which exhaust gas subjected to heat exchange is discharged downstream. The exhaust gas pipe 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 exhaust gas pipe 58, and the combustion burners 21, 22, 23, The temperature of the combustion air supplied to 24 and 25 can be raised.

  Although not shown, the exhaust gas pipe 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.

  Accordingly, when the pulverized coal machines 31, 32, 33, 34, and 35 are driven, the generated pulverized coal together with the conveying air passes through the pulverized coal supply pipes 26, 27, 28, 29, and 30 and the combustion burners 21, 22, 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 the pulverized fuel mixture mixed with the pulverized coal and the carrier air into the furnace 11 and blow the 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 fuel 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, 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, the NOx reduction region A 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 55, 56, and 57, 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 51 and 52 and is superheated by the combustion gas. The superheated steam generated by the superheaters 51 and 52 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 53 and 54, 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 55, 56, and 57 of the flue 50 is subjected to removal of harmful substances such as NOx by a catalyst in a denitration device (not shown) in the exhaust gas pipe 58, 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.

  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 in which pulverized coal and carrier air are mixed, and the pulverized fuel mixture. Inject combustion air into the outside. 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).

  Incidentally, as shown in FIG. 1, in such a coal fired boiler 10, each combustion burner 21, 22, 23, 24, 25 blows pulverized fuel, which is a mixture of pulverized coal and air, into the furnace 11. However, the slagging property varies depending on the type of coal used, and 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. .

  Therefore, in Example 1, the 1st combustion burner which can form a flame by inject | pouring the 1st fuel gas which mixed the solid fuel and air of low slagging property into the furnace 11 is perpendicular | vertical rather than a 1st combustion burner. There is provided a second combustion burner which is disposed below the direction and which can form a flame by injecting a second fuel gas in which a highly slugging solid fuel and air are mixed into the furnace 11.

  In the coal fired boiler 10 of the first embodiment, for example, the upper combustion burners 21 and 22 are used as the first combustion burner capable of injecting the first fuel gas with low slagging property, and the second fuel gas with high slagging property is applied. The lower combustion burners 23, 24, and 25 are used as the second combustion burners that can be injected.

  Therefore, since the combustion burners (first combustion burners) 21 and 22 are connected to the pulverized coal machines 31 and 32 via the pulverized coal supply pipes 26 and 27, the pulverized coal machines 31 and 32 are provided with low slugging. It is applied as a first fuel pulverizer that pulverizes a solid fuel to form a pulverized fuel. The combustion burners (second combustion burners) 23, 24, 25 are connected to the pulverized coal machines 33, 34, 35 via the pulverized coal supply pipes 28, 29, 30. , 34, and 35 are applied as second fuel pulverizers that pulverize a highly slugging solid fuel to form finely divided fuel.

  In this case, the low slagging solid fuel is defined as a fuel having an ash melting temperature (ash melting point) of 1200 ° C. or higher, and the high slagging solid fuel is an ash melting temperature (ash melting point) from 1200. Defined as low fuel. In Example 1, a bituminous coal pulverized fuel is used as the low slagging solid fuel, and a subbituminous coal pulverized fuel is used as the high slagging solid fuel.

  In addition, the kind of fuel applied is not limited to this bituminous coal or subbituminous coal. For example, low slugging solid fuels include anthracite and semi-anthracite in addition to bituminous coal. On the other hand, high-slagging solid fuels include lignite, lignite, peat, coke, biomass, etc. with high moisture and oxygen in addition to subbituminous coal.

  Further, in the coal fired boiler 10 according to the first embodiment, the usage ratio of the first combustion burner and the second combustion burner depends on the mixing ratio of the low slagging solid fuel and the high slagging solid fuel in the solid fuel to be used. Is set. That is, if the ratio of the low slagging solid fuel in the solid fuel to be used is 40% and the ratio of the high slagging solid fuel is 60%, as described above, the two-stage combustion burner is used as the first combustion burner. 21 and 22 are applied, and three-stage combustion burners 23, 24, and 25 are applied as the second combustion burner.

  If the ratio of the low slagging solid fuel in the solid fuel used is 60% and the ratio of the high slagging solid fuel is 40%, the three-stage combustion burners 21, 22, 23 are used as the first combustion burner. And two-stage combustion burners 24 and 25 are applied as the second combustion burner. Further, if the ratio of the low slagging solid fuel in the solid fuel used is 20% and the ratio of the high slagging solid fuel is 80%, the one-stage combustion burner 21 is applied as the first combustion burner, Four-stage combustion burners 22, 23, 24, and 25 are applied as the second combustion burner. If the ratio of the low slagging solid fuel in the solid fuel to be used is 100%, all the combustion burners 21, 22, 23, 24, 25 are applied as the first combustion burner, and the high slagging solid fuel is applied. If the ratio is 100%, all the combustion burners 21, 22, 23, 24, 25 are applied as the second combustion burners.

  Therefore, when the pulverized coal machines 31, 32, 33, 34, and 35 are driven, the pulverized coal machines 31 and 32 pulverize the low slagging solid fuel, and the generated low slagging pulverized coal together with the conveying air. It supplies to the combustion burners 21 and 22 from the pulverized coal supply pipes 26 and 27. The pulverized coal machines 33, 34, and 35 pulverize the high slagging solid fuel, and the generated high slagging pulverized coal together with the air for conveyance from the pulverized coal supply pipes 28, 29, and 30 to the combustion burners 23, 24, 25.

  The combustion air heated by the air heater 59 is supplied from the air duct 37 to the combustion burners 21, 22, 23, 24, 25 via the wind box 36, and from the branch air duct 40 to the additional air nozzle 39. To be supplied.

  Then, the upper combustion burners 21 and 22 blow the low slagging pulverized fuel mixture mixture of the low slagging pulverized coal and the carrier air into the furnace 11 and the combustion air into the furnace 11. The lower combustion burners 23, 24, and 25 blow high slagging pulverized fuel mixture obtained by mixing high slagging pulverized coal and carrier air into the furnace 11 and blow combustion air into the furnace 11.

  Therefore, in the furnace 11, a low slagging pulverized fuel mixture is blown from the upper combustion burners 21 and 22 to form a flame when ignited, and a high slagging pulverized powder is formed from the lower combustion burners 23, 24, and 25. A fuel mixture is blown and a flame is formed by ignition. At this time, although the furnace 11 has a high heat load on the upper side, the low slagging pulverized fuel has a high ash melting point, so it is difficult to melt, and the molten ash on the inner wall of the furnace 11 and the tips of the combustion burners 21 and 22 Is suppressed and the occurrence of slugging is prevented. In addition, although the furnace 11 has a low thermal load on the lower side, the highly slugging pulverized fuel is also difficult to melt because of its low ash melting point, and melts at the inner wall of the furnace 11 and the tips of the combustion burners 23, 24, 25. Ash adhesion is suppressed and slagging is prevented from occurring.

  As described above, in the boiler according to the first embodiment, the upper combustion burner (the first combustion burner that can form a flame by blowing the first fuel gas in which the low-slugging solid fuel and the air are mixed into the furnace 11 is formed. Combustion burners) 21 and 22 and lower combustion burners (second combustion burners) 23 capable of forming a flame by blowing a second fuel gas mixed with highly slugging solid fuel and air into the furnace 11, 24 and 25 are provided.

  Accordingly, when considering the heat flux distribution in the vertical direction in the furnace 11, it is high in the vicinity of the combustion burner 21 on the upper stage side, and slugging is likely to occur. Accordingly, the combustion burners (first combustion burners) 21 and 22 arranged on the upper stage side form a flame by injecting the first fuel gas having low slagging property into the furnace 11, and the combustion arranged on the lower stage side. The burners (second combustion burners) 23, 24, and 25 blow the second fuel gas having high slagging properties into the furnace 11. Therefore, the first fuel gas with low slagging property is supplied to the region of the furnace 11 where the heat load is high, and adhesion of molten ash on the tip portions of the combustion burners 21, 22, 23, 24, and 25 and the furnace wall is suppressed. Thus, the occurrence of slagging can be suppressed.

  In the boiler according to the first embodiment, the upper combustion burners (first combustion burners) 21 and 22 are provided with pulverized coal machines (first fuel pulverizers) 31 and 32 that pulverize low slagging solid fuel to form pulverized fuel. The pulverized coal machines (second fuel pulverizers) 33, 34, and 35 are connected to the lower combustion burners (second combustion burners) 23, 24, and 25 to pulverize the slagging solid fuel and form the pulverized fuel. It is connected. Therefore, by connecting the dedicated fuel pulverizers 31, 32, 33, 34, 35 capable of supplying a predetermined pulverized fuel for each of the combustion burners 21, 22, 23, 24, 25, the combustion burners 21, 22, 22 are connected. It is possible to easily supply the pulverized fuel with low slagging property or the pulverized fuel with high slagging property to 23, 24 and 25.

  In the boiler according to the first embodiment, the furnace 11 is provided with a plurality of combustion burners 21, 22, 23, 24, and 25 along the vertical direction, and the solid fuel having a low slagging property and the solid fuel having a high slagging property are used. The usage ratio of the first combustion burner and the second combustion burner is set according to the mixing ratio. Accordingly, the structure of the plurality of combustion burners 21, 22, 23, 24, and 25 is the same, and each solid fuel is changed according to the mixing ratio of the low slagging solid fuel and the high slagging solid fuel in the solid fuel to be used. The use ratio of the combustion burner to be injected, that is, the combustion burners 21, 22, 23, 24, 25 to be used can be set, and it is not necessary to form each combustion burner 21, 22, 23, 24, 25 individually. Therefore, it is possible to simplify the structure and reduce the cost. Moreover, even if the type (mixing ratio) of the solid fuel used in the furnace 11 is changed, it can be easily applied and versatility can be improved.

  In the boiler of the first embodiment, a fuel having an ash melting temperature higher than 1200 degrees is used as a low-slagging solid fuel. Specifically, bituminous coal pulverized fuel is used as a low slagging solid fuel, and subbituminous coal pulverized fuel is used as a high slagging solid fuel. Generation of slugging at the tip of the combustion burner and the furnace wall can be suppressed by using an inexpensive solid fuel.

  3 is a schematic configuration diagram illustrating a coal fired boiler according to a second embodiment of the present invention, FIG. 4 is a schematic diagram illustrating a low slagging combustion burner, and FIG. 5 is a schematic diagram illustrating another low slagging combustion burner. It is. In addition, the same code | symbol is attached | subjected to the member which has the function similar to the Example mentioned above, and detailed description is abbreviate | omitted.

  In Example 2, as shown in FIG. 3, the coal-fired boiler 10 is a conventional boiler, and includes a furnace 11 and a combustion device 60. 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 60 is provided in the lower part of the furnace wall (heat transfer tube) constituting the furnace 11. The combustion device 60 has a plurality of combustion burners 61, 62, 63, 64, 65 mounted on the furnace wall. In this embodiment, the combustion burners 61, 62, 63, 64, and 65 are arranged as four sets at equal intervals along the circumferential direction, and 5 sets along the vertical direction. Five stages are arranged.

  Each combustion burner 61, 62, 63, 64, 65 is connected to a pulverized coal machine 31, 32, 33, 34, 35 via a pulverized coal supply pipe 26, 27, 28, 29, 30. Accordingly, the pulverized coal machines 31, 32, 33, 34, and 35 pulverize the coal to a predetermined size and classify the pulverized coal classified by the carrier air (primary air) into the pulverized coal supply pipes 26, 27, 28, and 29. 30 to the combustion burners 61, 62, 63, 64, 65.

  Further, the furnace 11 is provided with a wind box 36 at a mounting position of each combustion burner 61, 62, 63, 64, 65, and one end portion of an air duct 37 is connected to the wind box 36. The duct 37 has a blower 38 attached to the other end. Therefore, the combustion air (additional air) sent by the blower 38 can be supplied from the air duct 37 to the wind box 36, and can be supplied from the wind box 36 to the combustion burners 61, 62, 63, 64, 65. . Therefore, in the combustion apparatus 60, each combustion burner 61, 62, 63, 64, 65 can blow a pulverized fuel mixture obtained by mixing pulverized coal and primary air into the furnace 11, and an ignition torch (not shown) Thus, a flame can be formed by igniting the pulverized fuel mixture.

  In the second embodiment, a first combustion burner capable of forming a flame by blowing a first fuel gas obtained by mixing solid fuel and air having low slagging properties into the furnace 11 and a direction perpendicular to the first combustion burner. There is provided a second combustion burner that is disposed below and capable of forming a flame by injecting a second fuel gas mixed with highly slugging solid fuel and air into the furnace 11. Specifically, as the first combustion burner capable of injecting the first fuel gas having low slagging property, the upper combustion burners 61 and 62 are applied, and the second combustion burner capable of injecting the second fuel gas having high slagging property. As shown, lower combustion burners 63, 64, and 65 are applied.

  Therefore, the combustion burners (first combustion burners) 61 and 62 are connected to the pulverized coal machines 31 and 32 via the pulverized coal supply pipes 26 and 27, so that the pulverized coal machines 31 and 32 are low slugging. It is applied as a first fuel pulverizer that pulverizes a solid fuel to form a pulverized fuel. The combustion burners (second combustion burners) 63, 64, 65 are connected to the pulverized coal machines 33, 34, 35 via the pulverized coal supply pipes 28, 29, 30. , 34, and 35 are applied as second fuel pulverizers that pulverize a highly slugging solid fuel to form finely divided fuel.

  Further, the combustion burners (first combustion burners) 61 and 62 arranged on the upper side are low-slagging fuel combustion burners in which the concentration of the solid fuel is increased in the center of the jet of the first fuel gas. Hereinafter, the combustion burner for low slagging fuel will be described.

  As shown in FIG. 4, the low slagging fuel combustion burner is provided with a fuel nozzle 102 at the tip of a pulverized coal supply pipe 101 and an air nozzle 103 outside the fuel nozzle 102. The fuel nozzle 102 can blow a pulverized fuel mixture obtained by mixing pulverized coal and carrier air into the furnace 104, and the air nozzle 103 can blow primary air into the furnace 104. Further, the pulverized coal supply pipe 101 is provided with a deflector block 105, a twist plate 106, and a deflector block 107 therein.

  Accordingly, when the pulverized fuel mixture flows in the pulverized coal supply pipe 101, the concentration distribution of the pulverized coal changes by the deflector block 105, and after being twisted by the twist plate 106, the concentration of the pulverized coal again by the deflector block 107. Distribution changes. The fuel nozzle 102 ejects the pulverized fuel mixture into the furnace 104. At this time, the fuel nozzle 102 ejects the pulverized fuel mixture so as to be biased toward the center away from the furnace wall. By blowing out primary air from 103, an air-rich region B is formed in the vicinity of the furnace wall. For this reason, the concentration of the solid fuel at the center of the jet of the pulverized fuel mixture (first fuel gas) is increased, so that adhesion of molten ash on the inner wall of the furnace 104 is suppressed.

  In addition, as shown in FIG. 5, another low slagging fuel combustion burner includes a first nozzle 111 capable of injecting a pulverized fuel mixture obtained by mixing pulverized fuel and carrier air, and the first nozzle 111. To the second nozzle 112 capable of blowing combustion air (air) from the outside, the flame holders 113 and 114 provided at the tip portions of the first nozzle 111 and the second nozzle 112, and the flame holders 113 and 114 And a third nozzle 115 capable of blowing air from the first nozzle 111 toward the flame holding section 113 for suppressing the flow of pulverized coal in the pulverized fuel mixture.

  Accordingly, the first nozzle 111 blows in a pulverized fuel mixture in which pulverized fuel and carrier air are mixed, while the second nozzle 112 ignites near the outlets of the nozzles 111 and 112 by blowing in combustion air. It becomes a flame. At this time, since the air is blown so as to surround the blown pulverized fuel mixture, it is possible to form an appropriate flame without fear of misfire. In addition, since the wide-angle flame holding portions 113 and 114 are provided at the tip portions of the first nozzle 111 and the second nozzle 112, a vortex that flows and circulates outside is formed here, and misfire is suppressed. The

  Further, the third nozzle 115 blows in combustion air, and the combustion air flows along the inner wall surface of the first nozzle 111 and flows into the flame holding portion 113. Therefore, the pulverized coal in the pulverized fuel mixture flowing in the first nozzle 111 is blown off from the inner wall surface of the first nozzle 111 by this air and moves to the center side. The pulverized coal concentration in the fuel mixture decreases. Since the pulverized fuel mixture contains pulverized coal, molten ash is generated when it is burned. However, since the concentration of pulverized coal in the pulverized fuel mixture flowing to the flame holding portions 113 and 114 is low, the amount of molten ash generated here is very small, and adhesion of the molten ash to the flame holding portions 113 and 114 is prevented. The

  Here, although two types of combustion burners for low slagging fuel have been described, the present invention is not limited to this configuration.

  The coal-fired boiler 10 of the second embodiment is different from the first embodiment only in the configuration of the combustion burners 61, 62, 63, 64, 65, and the other configurations are the same. Is omitted.

  Therefore, when the pulverized coal machines 31, 32, 33, 34, and 35 are driven, the pulverized coal machines 31 and 32 pulverize the low slagging solid fuel, and the generated low slagging pulverized coal together with the conveying air. It supplies to the combustion burners 61 and 62 from the pulverized coal supply pipes 26 and 27. The pulverized coal machines 33, 34, and 35 pulverize the high slagging solid fuel, and the generated high slagging pulverized coal together with the air for conveyance from the pulverized coal supply pipes 28, 29, 30 to the combustion burners 63, 64, 65.

  Then, the upper combustion burners 61 and 62 inject the low slagging pulverized fuel mixture in which the low slagging pulverized coal and the carrier air are mixed into the furnace 11 and the combustion air into the furnace 11. The lower combustion burners 63, 64, and 65 blow a high slagging pulverized fuel mixture mixture of slagging pulverized coal and carrier air into the furnace 11 and blow combustion air into the furnace 11.

  Therefore, in the furnace 11, a low slagging pulverized fuel mixture is blown from the upper combustion burners 61 and 62, and a flame is formed by igniting, and a high slagging pulverized powder is formed from the lower combustion burners 63, 64 and 65. A fuel mixture is blown and a flame is formed by ignition. At this time, although the furnace 11 has a high heat load on the upper side, the low slagging pulverized fuel is difficult to melt because of its high ash melting point, and the molten ash on the inner wall of the furnace 11 and the tips of the combustion burners 61 and 62 Is suppressed and the occurrence of slugging is prevented. In addition, since the furnace 11 has a low thermal load on the lower side, the high slugging pulverized fuel has a low ash melting point, but adhesion of molten ash on the inner wall of the furnace 11 and the tips of the combustion burners 63, 64, 65 is difficult. It is suppressed and the occurrence of slagging is prevented.

  In addition, since the combustion burners (first combustion burners) 61 and 62 arranged on the upper stage side are low slagging fuel combustion burners, the combustion burners 61 and 62 are injected into the furnace 11 with the first fuel gas. Has a high concentration of solid fuel in the central part of the jet, and a low concentration of solid fuel around it. Therefore, since the concentration of the solid fuel on the outer peripheral side of the first fuel gas becomes low, the molten ash generated here is reduced, and the molten ash on the inner wall of the furnace 11 and the tips of the combustion burners 63, 64, 65 is reduced. Adhesion is suppressed and the occurrence of slagging is prevented.

  As described above, in the boiler according to the second embodiment, the upper combustion burners (first combustion burners) 61 and 62 for blowing the first fuel gas having the low slagging property and the lower stage for blowing the second fuel gas having the high slagging property are used. Combustion burners (second combustion burners) 63, 64, and 65 are provided, and upper combustion burners (first combustion burners) 61 and 62 are provided with low slugging that increases the concentration of solid fuel in the center of the jet of the first fuel gas. It is a combustion burner for natural fuel.

  Accordingly, the concentration of the solid fuel on the outer peripheral side of the first fuel gas is reduced, and the molten ash generated here is reduced. Therefore, the adhesion of the molten ash on the tip portions of the combustion burners 61 and 62 and the furnace wall is suppressed. The occurrence of slugging can be suppressed.

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

DESCRIPTION OF SYMBOLS 10 Coal-fired boiler 11 Furnace 12 Combustion device 21, 22 Combustion burner (1st combustion burner)
23, 24, 25 Combustion burner (second combustion burner)
26, 27, 28, 29, 30 Pulverized coal supply pipe 31, 32 Pulverized coal machine (first fuel crusher)
33, 34, 35 Pulverized coal machine (second fuel crusher)
36 Wind box 37 Air duct 39 Additional air nozzle 40 Branch air duct 50 Chimney 51, 52 Superheater (heat exchanger)
53, 54 Reheater (Heat exchanger)
55, 56, 57 economizer (heat exchanger)

Claims (6)

A furnace that is hollow and installed along the vertical direction;
A first combustion burner capable of forming a flame by blowing a first fuel gas in which a low-slagging solid fuel and air are mixed into the furnace;
A second combustion burner disposed below the first combustion burner and capable of forming a flame by injecting a second fuel gas mixed with highly slugging solid fuel and air into the furnace; ,
A heat exchanger provided at the top of the furnace to recover the internal heat;
The boiler characterized by having.   A first fuel pulverizer for pulverizing the low slagging solid fuel to form a pulverized fuel is connected to the first combustion burner, and the high slagging solid fuel is pulverized to the pulverized fuel to the second combustion burner. The boiler according to claim 1, wherein a second fuel pulverizer that forms a cylinder is connected.   The furnace is provided with a plurality of combustion burners along the vertical direction, and the first combustion burner and the first combustion burner according to a mixing ratio of the low slugging solid fuel and the high slugging solid fuel in the solid fuel to be used. The boiler according to claim 1 or 2, wherein a use ratio of two combustion burners is set.   The said 1st combustion burner is a combustion burner for low slagging fuel with which the density | concentration of the solid fuel in the center part of the jet of 1st fuel gas becomes high, The combustion burner for any one of Claim 1 to 3 characterized by the above-mentioned. Boiler.   The boiler according to any one of claims 1 to 4, wherein a fuel having an ash melting temperature higher than 1200 degrees is used as the low-slagging solid fuel.   6. The fine bituminous coal fuel is used as the low slagging solid fuel, and the subbituminous coal fine fuel is used as the high slagging solid fuel. boiler.

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