Burner, boiler, and power generation plant

Abstract

Provided is a burner in which a nitride layer does not readily form on an inner surface of a furnace wall. The present invention is provided with: a fuel ejection part (21x) in which a fuel ejection port (21x1) for ejecting ammonia-containing fuel is formed; and an air ejection part (21y) in which an air ejection port (21y1) for ejecting combustion air is formed. If three axes orthogonal to each other are defined as a first axis (C1), a second axis (C2), and a third axis (C3), the air ejection port (21y1) is disposed around the fuel ejection port (21x1) about the first axis (C1), the dimension (LC2) along the second axis (C2) in a second region (R2) of the air ejection port (21y1) adjacent to the fuel ejection port (21x1) in the direction of the second axis (C2) is larger than the dimension LC3 along the third axis (C3) in a third region (R3) of the air ejection port (21y1) adjacent to the fuel ejection port (21x1) in the direction of the third axis (C3).

Description

Burner, Boiler and Power Generation Plant

[0001] The present disclosure relates to a burner, a boiler and a power generation plant.

[0002] In solid fuel-fired boilers (e.g., pulverized coal-fired boilers), a combustion method called swirling combustion, in which fuel and air are burned while being swirled, is known (Patent Document 1).

[0003] Japanese Unexamined Patent Application Publication No. 2023-3988

[0004] In a boiler using an ammonia-containing fuel as disclosed in Patent Document 1, ammonia may contact the inner surface of a furnace wall located on a side of the burner. When ammonia contacts the inner surface of a metal furnace wall in a high-temperature atmosphere inside the furnace, a nitride layer may be formed on the inner surface of the furnace wall. When a nitride layer is formed on the inner surface of the furnace wall, the inner surface of the furnace wall is inevitably hardened (toughness decreases and brittleness increases), making the furnace wall prone to fracture against strain caused by thermal expansion or the like.

[0005] The present disclosure has been made in view of such circumstances, and an object thereof is to provide a burner, a boiler, and a power generation plant in which a nitride layer is less likely to be formed on the inner surface of the furnace wall.

[0006] In order to solve the above problem, the burner, boiler and power generation plant of the present disclosure employ the following means.

[0007] A burner according to an aspect of the present disclosure includes: a fuel ejection portion having a fuel ejection port formed therein through which ammonia-containing fuel is ejected; and an air ejection portion having an air ejection port formed therein through which combustion air is ejected. When three mutually orthogonal axes are defined as a first axis, a second axis, and a third axis, the air ejection ports are arranged around the fuel ejection port around the first axis, and a dimension along the second axis of a second region of the air ejection port adjacent to the fuel ejection port in the second axis direction is larger than a dimension along the third axis of a third region of the air ejection port adjacent to the fuel ejection port in the third axis direction.

[0008] A boiler according to an aspect of the present disclosure includes the burner described above.

[0009] A power plant according to one aspect of this disclosure includes the boiler.

[0010] According to this disclosure, it is possible to provide a burner, boiler, and power plant in which a nitride layer is less likely to form on the surface of the furnace wall.

[0011] This is a schematic diagram of a boiler according to one embodiment of the present disclosure. This is a cross-sectional view (horizontal cross-sectional view) passing through the burner of the boiler shown in Figure 1. This is a diagram showing the steam system (water system) of a power plant equipped with a boiler according to one embodiment of the present disclosure. This is a front view of a burn a modified example of one embodiment of the present disclosure. This is a plan view of the burner shown in Figure 6. This is a schematic diagram of a part of a boiler according to a modified example of one embodiment of the present disclosure. This is a side view of the burner shown in Figure 6.

[0012] Hereinafter, a burner, boiler, and power plant according to one embodiment of this disclosure will be described with reference to the drawings.

[0013] This disclosure is not limited by this embodiment. Furthermore, if there are multiple embodiments, examples, or modifications, they may be combined to form the present invention. Also, "up" or "upper" refers to the vertical direction upwards, and "down" or "downward" refers to the vertical direction downwards. However, the vertical direction may include some error.

[0014] [About the configuration of the power plant] Figure 1 is a schematic diagram showing the boiler 10 provided in the power plant 1. The boiler 10 is a facility that burns finely powdered fuel and / or fuel containing ammonia (hereinafter referred to as "ammonia-containing fuel") obtained by crushing solid fuel in multiple burners 21, and generates steam (superheated steam) by heating the boiler feedwater and steam with the heat of the combustion gas generated by the combustion. In other words, the boiler 10 can co-fire ammonia-containing fuel with other fuels, or exclusively fire ammonia-containing fuel.

[0015] Examples of solid fuels include biomass fuels and coal. Ammonia-containing fuels may be in gaseous or liquid form, and their state is not particularly limited.

[0016] The boiler 10 of this embodiment includes a furnace 11, a combustion device 20, a combustion gas passage 12, and a flue 13.

[0017] The furnace 11 has the shape of a hollow rectangular prism and is installed along the vertical direction. The furnace wall 101 that constitutes the inner wall surface of the furnace 11 has a plurality of heat transfer tubes and fins that connect the heat transfer tubes to each other, and is configured to recover heat generated by the combustion of pulverized fuel and / or ammonia-containing fuel by exchanging heat with boiler feedwater or steam flowing inside each heat transfer tube.

[0018] The combustion device 20 is installed in the lower region of the furnace 11. The combustion device 20 has a plurality of burners 21A, 21B, 21C, 21D, 21E, 21F (sometimes collectively referred to as "burner 21") mounted on the furnace wall 101 and a wind box 23. As shown in Figures 1 and 2, a plurality of burners 21 are provided along the circumferential direction of the furnace 11 at the same position in the vertical direction, and multiple such sets are installed along the vertical direction. In the case of Figures 1 and 2, for example, four burners 21 are provided near each corner of the furnace 11, which has a rectangular cross-sectional shape (cross-sectional shape in a plane perpendicular to the axis Cf indicating the central axis of the furnace 11), and six such sets are installed along the vertical direction. Note that in Figure 1, for illustrative purposes, only two of the four burners 21 included in each set are shown, and each set is labeled with reference numerals 21A, 21B, 21C, 21D, 21E, and 21F.

[0019] As shown in Figure 2, the axis Cb representing the central axis of each of the four burners 21 included in the same set (four burners 21 located in the same position / stage in the vertical direction) extends horizontally and is eccentric to the axis Cf of the furnace 11, which extends vertically, without intersecting it. Furthermore, the four burners 21 included in the same set are arranged to be 90 degrees rotationally symmetric with respect to the axis Cf of the furnace 11. By arranging each burner 21 in this way, the flames formed by each burner 21 form a swirling flow F on a virtual circle tangent to each axis Cb. In other words, a boiler 10 with a swirling combustion method is constructed. In the case of Figure 2, a counterclockwise swirling flow F is formed.

[0020] Figures 1 and 2 are examples, and the shape of the furnace, the number of burner stages, the number of burners in each stage, and the arrangement of the burners are not limited to the above configurations, as long as a swirling combustion boiler 10 is constructed. Typically, in a swirling combustion boiler, the number of burners in each stage is 4 or 8.

[0021] As shown in Figure 1, each of the burners 21A, 21B, 21C, 21D, 21E, and 21F is connected to one end of a fuel supply pipe that supplies fuel. The fuel supply pipe includes, for example, a pulverized fuel supply pipe 22 that supplies solid fuel and / or an ammonia-containing fuel supply pipe 160 that supplies ammonia-containing fuel. The other ends of the pulverized fuel supply pipes 22A, 22B, 22C, 22D, 22E, and 22F (sometimes collectively referred to as "pulverized fuel supply pipe 22") are connected to mills 31A, 31B, 31C, 31D, 31E, and 31F (sometimes collectively referred to as "mill 31"). The other end of the ammonia-containing fuel supply pipe 160 is connected to a source of ammonia-containing fuel (not shown). The ammonia-containing fuel supply pipe 160 may include a main supply pipe 161 connected to a source of ammonia-containing fuel, and branch supply pipes 162 that connect the main supply pipe 161 to each burner 21 and supply ammonia-containing fuel to each burner 21.

[0022] Each burner 21 is supplied with either pulverized fuel and ammonia-containing fuel, or either pulverized fuel or ammonia-containing fuel. However, at least one set of burners 21A, 21B, 21C, 21D, 21E, and 21F, or at least one of the four burners 21 constituting one set, is supplied with at least ammonia-containing fuel. In other words, at least one of the burners 21 is capable of co-firing pulverized fuel and ammonia-containing fuel, or exclusively firing ammonia-containing fuel.

[0023] Mill 31 is equipment that produces fine fuel by crushing solid fuel. Mill 31 is a vertical roller mill configured such that, for example, a crushing table (not shown) is supported inside so as to be rotatable, and a plurality of crushing rollers (not shown) are supported above the crushing table so as to be rotatable in conjunction with the rotation of the crushing table. The solid fuel crushed by the cooperation of the crushing rollers and the crushing table is conveyed to a classifier (not shown) provided in Mill 31 by primary air (conveyor gas, oxidizing gas) supplied to Mill 31. In the classifier, the crushed solid fuel is classified into fine fuel with a particle size of a size suitable for combustion in Burner 21 and coarse fuel with a particle size larger than that. The fine fuel that has passed through the classifier is supplied to Burner 21 via the fine fuel supply pipe 22 along with the primary air. The coarse fuel that has not passed through the classifier falls onto the crushing table inside Mill 31 by its own weight and is crushed again.

[0024] Outside the furnace 11 at the positions where each burner 21 is installed, a wind box 23 is provided. One end of an air duct (air supply line) 24 is connected to the wind box 23. On the other hand, a forced draft fan 32 (FDF) is provided at the other end of the air duct 24. The air supplied from the forced draft fan 32 is heated by an air preheater 42 installed in the air duct 24, and is supplied to each burner 21 as secondary air (combustion air, oxidizing gas) via the wind box 23 and introduced into the furnace 11. The air duct 24 may be provided with a flow rate adjustment mechanism (not shown) such as a damper to adjust the flow rate of the secondary air supplied to each burner 21.

[0025] Above the wind box 23, a plurality of additional air ports 27 are provided for supplying additional combustion air (AA) into the furnace 11. One end of an additional air duct 28, which branches off from the air duct 24, is connected to each additional air port 27. On the other hand, the other end of the additional air duct 28 is connected to the portion of the air duct 24 downstream of the air preheater 42. This allows a portion of the combustion air supplied from the forced draft fan 32 and flowing through the air duct 24 to be supplied to the additional air ports 27 as additional combustion air via the additional air duct 28. The additional air duct 28 may be provided with a flow rate adjustment mechanism (not shown), such as a damper, to adjust the flow rate of the additional combustion air supplied to each additional air port 27.

[0026] The combustion gas passage 12 is connected to the upper vertical part of the furnace 11. The combustion gas passage 12 is equipped with superheaters 102A, 102B, 102C (sometimes collectively referred to as "superheater 102"), reheaters 103A, 103B (sometimes collectively referred to as "reheater 103"), and an economizer 104 as heat exchangers for recovering heat from the combustion gas. Heat exchange takes place between the combustion gas generated in the furnace 11 and the boiler feedwater or steam flowing inside each heat exchanger. Note that the number, arrangement, and shape of each heat exchanger are not limited to the configuration shown in Figure 1.

[0027] Downstream of the combustion gas passage 12 is a flue 13 through which the combustion gas, from which heat has been recovered by each heat exchanger, is discharged. The flue 13 is equipped with an air preheater 42, which is configured to exchange heat between the air flowing through the air duct 24 and the combustion gas flowing through the flue 13. By heating the secondary air supplied to the burner 21 and the additional air port 27 with the air preheater 42, further heat can be recovered from the combustion gas after it has exchanged heat with the boiler feedwater or steam.

[0028] A denitrification device 43 may be provided upstream of the air preheater 42 in the flue 13. The denitrification device 43 supplies a reducing agent, such as ammonia or urea solution, which has the effect of reducing nitrogen oxides, to the combustion gas flowing through the flue 13. The reaction between the nitrogen oxides (NOx) in the combustion gas to which the reducing agent has been supplied and the reducing agent is promoted by the catalytic action of a denitrification catalyst installed in the denitrification device 43, thereby removing and reducing nitrogen oxides in the combustion gas.

[0029] A gas duct 41 is connected downstream of the air preheater 42 in the flue 13. The gas duct 41 is equipped with dust collection devices 44, such as an electrostatic precipitator, to remove ash and other particles from the combustion gas, and environmental devices such as a desulfurization device 46 to remove sulfur oxides, as well as an induced draft fan (IDF) 45 to guide the exhaust gas to these environmental devices. The downstream end of the gas duct 41 is connected to a chimney 47, and the combustion gas treated by the environmental devices is discharged from the chimney 47 as exhaust gas.

[0030] When co-firing pulverized fuel and ammonia-containing fuel, the mill 31 is started. When the mill 31 is started, the crushed and classified pulverized fuel is supplied to the burner 21 via the pulverized fuel supply pipe 22 along with primary air. Secondary air heated by the air preheater 42 is also supplied to the burner 21 from the air duct 24 via the wind box 23. Ammonia-containing fuel is also supplied to the burner 21 via the ammonia-containing fuel supply pipe 160. In addition, co-firing of pulverized fuel and ammonia-containing fuel may be performed in some of the burners 21, while the remaining burners 21 may exclusively fire either pulverized fuel or ammonia-containing fuel.

[0031] In the case of co-firing of pulverized fuel and ammonia-containing fuel, the burner 21 injects a mixture of pulverized fuel and primary air, along with the ammonia-containing fuel, into the furnace 11, and also injects secondary air into the furnace 11. In the case of exclusive firing of ammonia-containing fuel, the burner 21 injects the ammonia-containing fuel into the furnace 11, along with secondary air. The pulverized fuel mixture and ammonia-containing fuel injected into the furnace 11 are ignited and react with the secondary air to form a flame. A flame is formed in the lower region of the furnace 11 (the region corresponding to the height range of installation of the wind box 23), and high-temperature combustion gases rise inside the furnace 11 and flow into the combustion gas passage 12.

[0032] In this embodiment, air is used as the oxidizing gas (primary air, secondary air), but a gas with a higher or lower oxygen content than air may also be used. By adjusting the ratio of oxygen to the supplied fuel to an appropriate range, stable combustion can be achieved in the furnace 11.

[0033] The combustion gas flowing into the combustion gas passage 12 exchanges heat with water or steam in the superheater 102, reheater 103, and economizer 104 located inside the combustion gas passage 12, before being discharged into the flue 13. There, nitrogen oxides are removed in the denitrification device 43, and after exchanging heat with primary and secondary air in the air preheater 42, it is further discharged into the gas duct 41. Ash and other contaminants are removed in the dust collector 44, and sulfur oxides are removed in the desulfurization device 46 before being discharged out of the system from the chimney 47. Note that the arrangement of each heat exchanger in the combustion gas passage 12 and each device from the flue 13 to the gas duct 41 does not necessarily have to be in the order described above with respect to the combustion gas flow.

[0034] Next, the superheater 102, reheater 103, and economizer 104, which are installed in the combustion gas passage 12 as heat exchangers, will be described in detail. Figure 3 is a diagram showing the steam system (water system) of the power plant 1. Note that Figure 1 does not accurately show the positions of each heat exchanger (superheaters 102A, 102B, 102C, reheaters 103A, 103B, economizer 104) in the combustion gas passage 12, and the order of each heat exchanger with respect to the combustion gas flow is not limited to what is shown in Figure 1.

[0035] As shown in Figure 3, the power plant 1 comprises heat exchangers installed in the boiler 10, a steam turbine 111 that is rotationally driven by the steam generated in the boiler 10, and a generator 113 connected to the steam turbine 111 that generates electricity using the rotational force of the steam turbine 111.

[0036] The steam turbine 111 includes, for example, a high-pressure turbine 111A, an intermediate-pressure turbine 111B, and a low-pressure turbine 111C. Steam superheated in the superheater 102 of the boiler 10 rotates the high-pressure turbine 111A. The steam that has passed through the high-pressure turbine 111A is re-superheated in the reheater 103 of the boiler 10 and rotates the intermediate-pressure turbine 111B. The steam that has passed through the intermediate-pressure turbine 111B rotates the low-pressure turbine 111C.

[0037] A condenser 112 is connected to the low-pressure turbine 111C. The steam that rotates the low-pressure turbine 111C condenses in the condenser 112 through heat exchange with cooling water (for example, seawater, river water, or the returned heating feedwater described later) to become condensate (boiler feedwater). The condenser 112 is connected to the economizer 104 via the boiler feedwater line L1.

[0038] The boiler feedwater line L1 is equipped with, for example, a condensate pump 121 (CP), a low-pressure feedwater heater 122, a boiler feedwater pump 123 (BFP), and a high-pressure feedwater heater 124. The low-pressure feedwater heater 122 and the high-pressure feedwater heater 124 are devices that heat the boiler feedwater supplied to the economizer 104.

[0039] For example, if boiler 10 is a once-through boiler, the economizer 104 is connected to the heat transfer tubes that make up the furnace wall 101. The boiler feedwater heated in the economizer 104 via the boiler feedwater line L1 is heated by radiation from the flame in the furnace 11 as it passes through the heat transfer tubes that make up the furnace wall 101, and is then led to the steam-water separator 125. The steam separated in the steam-water separator 125 is supplied to the superheater 102. Meanwhile, the drain water separated in the steam-water separator 125 flows into the steam-water separator drain tank 126 and is led to the condenser 112 via the drain water line L2.

[0040] Furthermore, during startup or low-load operation of a once-through boiler, the boiler feedwater supplied from the economizer 104 may not evaporate completely as it passes through the heat transfer tubes constituting the furnace wall 101, resulting in an operating condition (wet operation condition) where a water level exists in the steam-water separator 125. In this wet operation condition, the drain water separated in the steam-water separator 125 and guided to the steam-water separator drain tank 126 may be recirculated and supplied from the economizer 104 to the heat transfer tubes constituting the furnace wall 101 by using a boiler circulation pump 127 (BCP) to merge it into the middle of the boiler feedwater line L1 via the circulation line L7.

[0041] As combustion gas flows through the combustion gas passage 12, heat is recovered from this combustion gas in the superheater 102, reheater 103, and economizer 104. Meanwhile, boiler feedwater supplied from the boiler feedwater pump 123 (BFP) is preheated in the economizer 104, then heated into steam as it passes through the heat transfer tubes that make up the furnace wall 101, and is led to the steam-water separator 125. The steam separated in the steam-water separator 125 is introduced into the first superheater 102A, the second superheater 102B, and the third superheater 102C, where it is superheated by the combustion gas. The superheated steam generated in the superheater 102 is supplied to the high-pressure turbine 111A via the steam line L3, and rotates the high-pressure turbine 111A. The steam discharged from the high-pressure turbine 111A is introduced into the first reheater 103A and the second reheater 103B via the steam line L4, where it is re-superheated. The steam reheated in each reheater is supplied to the intermediate-pressure turbine 111B via the steam line L5, which rotates the intermediate-pressure turbine 111B. The steam discharged from the intermediate-pressure turbine 111B is supplied to the low-pressure turbine 111C via the steam line L6, which rotates the low-pressure turbine 111C. The rotating shaft of the steam turbine 111 rotates the generator 113, generating electricity. The steam discharged from the low-pressure turbine 111C is cooled in the condenser 112 to become condensate, which is then sent to the economizer 104 as boiler feedwater via the boiler feedwater line L1.

[0042] [Regarding the Burner] In the following description, three mutually orthogonal axes are defined as a first axis C1, a second axis C2, and a third axis C3. The first axis C1 is an axis parallel to or coincident with the axis Cb of the burner 21, the second axis C2 is an axis extending along the horizontal direction, and the third axis C3 is an axis extending along the vertical direction.

[0043] FIG. 4 shows a front view of one burner 21, that is, a view of one burner 21 seen from the direction of an arrow pointing toward the outside of the furnace along the first axis C1. As shown in FIG. 4, the burner 21 includes a fuel ejection portion 21x formed with a fuel ejection port 21x1, and an air ejection portion 21y formed with an air ejection port 21y1.

[0044] The fuel ejection portion 21x is a portion that blows the ammonia-containing fuel supplied to the burner 21 into the furnace 11. A fuel ejection port 21x1 is formed at an end of the fuel ejection portion 21x facing the interior of the furnace. The fuel ejection port 21x1 is an opening for ejecting the ammonia-containing fuel guided to the fuel ejection portion 21x into the furnace. In the case of FIG. 4, the shape of the fuel ejection port 21x1 is a rounded rectangular shape that is long in the direction of the second axis C2 and short in the direction of the third axis C3. However, the shape of the fuel ejection port 21x1 is not limited to the form shown in FIG. 4, and may be, for example, circular or elliptical.

[0045] The air ejection portion 21y is a portion that blows the secondary air supplied to the burner 21 into the furnace 11. An air ejection port 21y1 is formed at an end of the air ejection portion 21y facing the interior of the furnace. The air ejection port 21y1 is an opening for ejecting the secondary air guided to the air ejection portion 21y into the furnace. When the burner 21 is viewed from the front, the air ejection port 21y1 is disposed around the fuel ejection port 21x1 around the axis Cb. That is, when the burner 21 is viewed from the front, the shape of the air ejection port 21y1 is a shape that surrounds the fuel ejection port 21x1 around the axis Cb. In the case of FIG. 4, the shape of the air ejection port 21y1 is a substantially rectangular annular shape surrounding the fuel ejection port 21x1. However, the shape of the air ejection port 21y1 is not limited to the form shown in FIG. 4, and may be another shape (for example, circular or elliptical) adapted to the shape of the fuel ejection port 21x1.

[0046] As shown in Figure 5, the air outlet 21y1 includes, for example, a second region R2 and a third region R3. In Figure 5, the second region R2 is shown with cross-hatching, but the illustrated boundary is not strictly defined. The second region R2 is the region of the air outlet 21y1 adjacent to the fuel outlet 21x1 in the direction of the second axis C2 (left-right direction) when the burner 21 is viewed from the front. That is, the second region R2 is the region of the air outlets 21y1 on both sides of the fuel outlet 21x1. In contrast, the third region R3 is the region of the air outlet 21y1 adjacent to the fuel outlet 21x1 in the direction of the third axis C3 (up-down direction) when the burner 21 is viewed from the front.

[0047] In such an air outlet 21y1, the dimension LC2 along the second axis C2 of the second region R2 is set to be larger than the dimension LC3 along the third axis C3 of the third region R3 (LC2 > LC3). Preferably, the dimension LC2 along the second axis C2 of the second region R2 is set to be more than 2 times and less than or equal to 3 times the dimension LC3 along the third axis C3 of the third region R3. This increases the amount of air ejected from the second region R2. By increasing the amount of air ejected from the second region R2, as shown in Figure 2, the concentration of ammonia-containing fuel (ammonia concentration) in contact with the inner surface of the furnace wall 101 on at least one side of the burner 21 can be reduced. For example, the concentration of ammonia-containing fuel (ammonia concentration) in contact with the inner surface of the furnace wall 101 in the region indicated by the symbol Rw in Figure 2 can be reduced. This makes it less likely for a nitride layer to form on the inner surface of the furnace wall 101.

[0048] [Modification] As shown in Fig. 6 and Fig. 7, a partition wall 21w may be provided at a portion of the air ejection portion 21y corresponding to the second region R2. As shown in Fig. 6, the partition wall 21w is a wall portion extending in the direction of the third axis C3 when the burner 21 is viewed from the front. Further, as shown in Fig. 7, the partition wall 21w is also a wall portion extending in the direction of the first axis C1 when the burner 21 is viewed from above. By means of this partition wall 21w, each portion of the air ejection portion 21y corresponding to the second region R2 is divided (physically partitioned) in the direction of the second axis C2 (the left-right direction). Here, for convenience, the air ejection portion 21y after division is defined as a main air ejection portion 21za and a sub air ejection portion 21zb, and the second region R2 after division is defined as a main second region R2a and a sub second region R2b for convenience.

[0049] The main second region R2a is a region located inward of the sub second region R2b in the direction of the second axis C2, and is also a region connected to the third region R3. That is, when the burner 21 is viewed from the front, the main second region R2a forms a substantially rectangular annular region surrounding the fuel ejection port 21x1 together with the third region R3.

[0050] The sub second region R2b is a region located outward of the main second region R2a in the direction of the second axis C2, and is a region independent of the third region R3 and the main second region R2a.

[0051] Note that the dimension LC2 along the second axis C2 of the second region R2 after division is the sum of the dimension along the second axis C2 of the main second region R2a and the dimension along the second axis C2 of the sub second region R2b. Naturally, the dimension LC2 along the second axis C2 of the second region R2 does not include the dimension of the partition wall 21w along the second axis C2.

[0052] By dividing the portion of the air ejection section 21y corresponding to the second region R2 with a partition wall 21w, the portion that ejects the air supplied to the burner 21 from the main second region R2a and blows it into the furnace 11 (main air ejection section 21za) and the portion that ejects the air from the sub-second region R2b and blows it into the furnace 11 (sub-air ejection section 21zb) are physically separated and become independent of each other. As a result, the flow rate of the air ejected from the main second region R2a and the flow rate of the air ejected from the sub-second region R2b can be adjusted independently. Therefore, for example, by increasing the flow velocity of the air ejected from the sub-second region R2b, the spread of the flame in the direction of the second axis C2 can be suppressed. Furthermore, since the main second region R2a and the sub-second region R2b are physically separated by the partition wall 21w, the airflow ejected from the main second region R2a and the airflow ejected from the sub-second region R2b can be suppressed from interfering with each other and thus rectified. As a result, the concentration of ammonia-containing fuel (ammonia concentration) in contact with the inner surface of the furnace wall 101 on at least one side of the burner 21 can be reduced. For example, the concentration of ammonia-containing fuel (ammonia concentration) in contact with the inner surface of the furnace wall 101 in the region indicated by the symbol Rw in Figure 2 can be reduced. This makes it less likely for a nitride layer to form on the inner surface of the furnace wall 101.

[0053] As shown in Figure 8, the boiler 10 may also be equipped with a damper (flow rate adjustment mechanism) 25 and a branch duct (branch line) 170.

[0054] The damper 25 is a mechanism for adjusting the flow rate of secondary air (more specifically, the flow rate of air directed to the main air outlet 21za) that is supplied to each burner 21.

[0055] The branch duct 170 is a duct that takes out a portion of the secondary air flowing through the air duct 24 and supplies it to the auxiliary air outlet 21zb. The branch duct 170 may be provided with a damper (flow rate adjustment mechanism) 171 for adjusting the flow rate of the secondary air supplied to the auxiliary air outlet 21zb.

[0056] The branch duct 170 is connected to the auxiliary air outlet 21zb (see Figures 7 and 9) and is configured to supply secondary air taken from the air duct 24 upstream of the damper 25 to the auxiliary air outlet 21zb of each burner 21. This allows air to be supplied independently to the main air outlet 21za and the auxiliary air outlet 21zb.

[0057] [Note] The burner, boiler, and power plant according to this embodiment, as described above, can be understood, for example, as follows.

[0058] A burner according to a first aspect of this disclosure comprises a fuel injection section (21x) formed with a fuel nozzle (21x1) from which ammonia-containing fuel is injected, and an air injection section (21y) formed with an air nozzle (21y1) from which combustion air is injected, wherein when three mutually orthogonal axes are designated as a first axis (C1), a second axis (C2), and a third axis (C3), the air nozzle (21y1) is located around the first axis (C1) The dimensions of the second region (R2) of the air nozzle (21y1) adjacent to the fuel nozzle (21x1) in the direction of the second axis (C2) are greater than the dimensions of the third region (R3) of the air nozzle (21y1) adjacent to the fuel nozzle (21x1) in the direction of the third axis (C3) are greater than the dimensions of the third region (R3) of the air nozzle (21y1) adjacent to the fuel nozzle (21x1) in the direction of the third axis (C3)

[0059] The air nozzles (21y1) are arranged around the fuel nozzles (21x1) around the first axis (C1). The dimension of the second region (R2) of the air nozzles (21y1) adjacent to the fuel nozzles (21x1) in the direction of the second axis (C2) is greater than the dimension of the third region (R3) of the air nozzles (21y1) adjacent to the fuel nozzles (21x1) in the direction of the third axis (C3) in the direction of the third axis (C3). As a result, the amount of air ejected from the second region (R2) increases. Therefore, for example, if the burner (21) is installed with the third axis (C3) in the vertical direction and the first axis (C1) in the direction of approximately perpendicular to the furnace wall (101) of the boiler (10), the concentration of ammonia in contact with the inner surface of the furnace wall (101) on the side of the burner (21) in the direction of the second axis (C2) can be reduced. As a result, it becomes less likely for a nitride layer to form on the inner surface of the furnace wall (101).

[0060] In the burner according to a second aspect of this disclosure, in the first aspect, the dimension of the second region (R2) along the second axis (C2) is set to be at most two times and not more than three times the dimension of the third region (R3) along the third axis (C3).

[0061] Since the dimension of the second region (R2) along the second axis (C2) is set to be more than twice but not more than three times the dimension of the third region (R3) along the third axis (C3), the amount of air ejected from the second region (R2) increases.

[0062] In a burner according to a third aspect of the present disclosure, in the first or second aspect, the second region (R2) is divided into a main second region (R2a) and a sub-second region (R2b) in the direction of the second axis (C2), and the air ejection section (21y) has a main air ejection section (21za) on which the main second region (R2a) is formed, and a sub-air ejection section (21zb) on which the sub-second region (R2b) is formed.

[0063] The air ejection section (21y) has a main air ejection section (21za) in which a main second region (R2a) is formed, and a secondary air ejection section (21zb) in which a secondary second region (R2b) is formed. Therefore, the flow rate of air ejected from each of the main air ejection section (21za) and the secondary air ejection section (21zb) can be adjusted independently. This allows, for example, increasing the flow rate of air ejected from the secondary second region (R2b) to suppress the spread of the flame in the direction of the second axis (C2).

[0064] In the burner according to the fourth aspect of the present disclosure, in the third aspect, a partition wall (21w) is provided that divides the air ejection section (21y) into the main air ejection section (21za) and the sub-air ejection section (21zb) in the direction of the second axis (C2).

[0065] Since a partition wall (21w) is provided that divides the air ejection section (21y) into a main air ejection section (21za) and a secondary air ejection section (21zb) in the direction of the second axis (C2), the airflow ejected from the main second region R2a and the airflow ejected from the secondary second region R2b can be suppressed from interfering with each other and thus the airflow can be straightened.

[0066] In the burner according to the fifth aspect of this disclosure, in any of the first to fourth aspects, the third axis (C3) is an axis along the vertical direction, and the first axis (C1) is substantially perpendicular to the furnace wall (101) of the boiler (10).

[0067] A boiler according to the sixth aspect of this disclosure comprises a burner (21) as described in any of the first to fifth aspects.

[0068] A boiler according to a seventh aspect of the present disclosure includes a burner (21) as described in the third aspect, an air supply line (24) for supplying combustion air to the burner (21), a flow rate adjustment mechanism (25) provided in the air supply line (24) and capable of adjusting the flow rate of combustion air supplied to the main air outlet (21za), and a branch line (170) for supplying air from the air supply line (24) upstream of the flow rate adjustment mechanism (25) to the auxiliary air outlet (21zb).

[0069] Since the system is equipped with a branch line (170) that supplies air from the air supply line (24) upstream of the flow rate adjustment mechanism (25) to the auxiliary air ejection section (21zb), air can be supplied independently to both the main air ejection section (21za) and the auxiliary air ejection section (21zb).

[0070] The power plant according to the eighth aspect of this disclosure comprises a boiler (10) as described in either the sixth or seventh aspect.

[0071] 1 Power Plant 10 Boiler 11 Furnace 12 Combustion Gas Passage 13 Flue 20 Combustion Equipment 21 (21A-21F) Burner 21w Partition 21x Fuel Injection Section 21x1 Fuel Injection Port 21y Air Injection Section 21y1 Air Injection Port 21za Main Air Injection Section 21zb Secondary Air Injection Section 22 (22A-22F) Fine Fuel Supply Pipe 23 Wind Box 24 Air Duct 25 Damper 27 Additional Air Port 28 Additional Air Duct 31 (31A-31F) Mill (Crusher) 32 Forced Fuel Fan (FDF) 41 Gas Duct 42 Air Preheater 43 Denitrification Equipment 44 Dust Collector 45 Induced draft fan (IDF) 46 Desulfurization unit 47 Chimney 101 Furnace wall 102 Superheater 102A First superheater 102B Second superheater 102C Third superheater 103 Reheater 103A First reheater 103B Second reheater 104 Economist 111 Steam turbine 111A High-pressure turbine 111B Intermediate-pressure turbine 111C Low-pressure turbine 160 Ammonia-containing fuel supply pipe 161 Main supply pipe 162 Branch supply pipe 170 Branch duct 171 Damper R2 Second region R2a Main second region R2b Sub-second region R3 Third region

Claims

1. A burner comprising: a fuel injection section formed with a fuel nozzle from which ammonia-containing fuel is ejected; and an air injection section formed with an air nozzle from which combustion air is ejected, wherein, when three mutually orthogonal axes are designated as the first axis, second axis, and third axis, the air nozzles are arranged around the fuel nozzles around the first axis, and the dimension along the second axis of the second region of the air nozzle adjacent to the fuel nozzle in the direction of the second axis is greater than the dimension along the third axis of the third region of the air nozzle adjacent to the fuel nozzle in the direction of the third axis.

2. The burner according to claim 1, wherein the dimension of the second region along the second axis is two times or more and three times or less the dimension of the third region along the third axis.

3. The burner according to claim 1, wherein the second region is divided into a main second region and a sub-second region in the direction of the second axis, and the air ejection section has a main air ejection section on which the main second region is formed, and a sub-air ejection section on which the sub-second region is formed.

4. The burner according to claim 3, wherein a partition wall is provided that divides the air ejection section into the main air ejection section and the sub-air ejection section in the direction of the second axis.

5. The burner according to any one of claims 1 to 4, wherein the third axis is an axis aligned in the vertical direction, and the first axis is substantially perpendicular to the furnace wall of the boiler.

6. A boiler equipped with the burner described in claim 1.

7. A boiler comprising: a burner according to claim 3; an air supply line for supplying combustion air to the burner; a flow rate adjustment mechanism provided in the air supply line and capable of adjusting the flow rate of combustion air supplied to the main air outlet; and a branch line for supplying air from the air supply line upstream of the flow rate adjustment mechanism to the auxiliary air outlet.

8. A power plant comprising the boiler described in claim 7.

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