burner

Abstract

Provided is a burner capable of suppressing NOx generation resulting from ammonia supply. A burner (21) comprises: a fuel nozzle (62) that extends in the direction of a central axis line (CL) and blows a fuel gas obtained by mixing a pulverized fuel and air into a furnace; a pulverized fuel supply pipe that introduces the fuel gas into the fuel nozzle (62) from a cross direction (A1) that intersects the central axis line (CL); and a plurality of ammonia nozzles (80) that are arranged around the central axis line (CL) and are capable of supplying ammonia fuel into the interior of the furnace. The amount of ammonia fuel supplied from the ammonia nozzles (80) is greater in a counter-fuel gas introduction area (AR1) positioned on the side opposite to the pulverized fuel supply pipe with respect to the central axis line (CL) than in a fuel gas introduction area (AR2) positioned on the side of the pulverized fuel supply pipe with respect to the central axis line (CL).

Description

Burner

[0001] The present disclosure relates to a burner using ammonia fuel.

[0002] Large boilers such as power generation boilers have a furnace installed vertically in a hollow shape, and a plurality of burners are arranged along the circumferential direction of the furnace on the furnace wall. Also, a large boiler has a flue connected above the furnace in the vertical direction, and a heat exchanger for generating steam is arranged in this flue. Then, a flame is formed when the burner injects a mixture of fuel and air (oxidizing gas) into the furnace, combustion gas is generated and flows into the flue. A heat exchanger is installed in the region where the combustion gas flows, and water or steam flowing in the heat transfer tubes constituting the heat exchanger is heated to generate superheated steam.

[0003] Patent Document 1 discloses a burner that supplies pulverized coal and primary air from a central nozzle and supplies ammonia fuel from a plurality of positions around the nozzle. By supplying ammonia to a flame (reduction region) with insufficient air, reduction of NOx generation is expected.

[0004] Japanese Unexamined Patent Application Publication No. 2021 - 165629

[0005] However, the pulverized coal supplied to the burner is introduced into the burner at a specific angle due to the routing constraints of the pulverized coal pipe that supplies the pulverized coal from the mill that pulverizes the coal to the burner. That is, the pulverized coal cannot be uniformly introduced along the axis of the nozzle that supplies the pulverized coal to the furnace.

[0006] For this reason, due to the difference in inertial force between the pulverized coal and air, the amount of pulverized coal supplied to the introduction direction side (the back side in the introduction direction) of the pulverized coal pipe is larger than the amount of pulverized coal supplied to the side opposite to the introduction direction (the front side in the introduction direction), resulting in a pulverized coal-rich state. Therefore, the reduction region formed by the pulverized coal flame is not uniformly formed around the circumference centered on the axis of the nozzle, and the degree of air deficiency (or the width of the air deficiency region) on the pulverized coal introduction direction side where the pulverized coal is rich becomes large. Since such non-uniformity of the pulverized coal concentration occurs, sufficient reduction of NOx by ammonia supply cannot be expected.

[0007] This disclosure has been made in view of these circumstances and aims to provide a burner that can suppress NOx generation caused by ammonia supply.

[0008] A burner according to one aspect of the present disclosure includes a fuel nozzle extending in the direction of an axis and injecting a fuel gas, which is a mixture of fuel and an oxidizing gas, into a furnace; a fuel gas introduction section that introduces the fuel gas into the fuel nozzle from a direction intersecting the axis; and a plurality of ammonia nozzles arranged around the axis and capable of supplying ammonia fuel into the furnace, wherein the amount of ammonia fuel supplied from each ammonia nozzle is greater in the anti-fuel gas introduction region located on the opposite side of the axis from the fuel gas introduction section than in the fuel gas introduction region where the fuel gas introduction section is located relative to the axis.

[0009] This can suppress NOx generation caused by ammonia supply.

[0010] This is a schematic diagram showing a boiler using the burner of this disclosure. Figure 1 is a longitudinal cross-sectional view showing the burner. Figure 2 is a front view showing the arrangement of the ammonia nozzles of the burner.

[0011] An embodiment of the present disclosure will be described below with reference to the drawings. This embodiment does not limit the present disclosure, and if there are multiple embodiments, they may be combinations of these embodiments. In the following description, "up" or "above" refers to the upper vertical direction, and "down" or "below" refers to the lower vertical direction; the vertical direction is not precise and includes some error.

[0012] Figure 1 shows a boiler 10 that uses solid fuel as its main fuel according to this embodiment.

[0013] Boiler 10 is a boiler that burns finely powdered fuel, obtained by crushing solid fuel, using a burner, and generates superheated steam by exchanging the heat produced by this combustion with feedwater or steam. Biomass fuel and coal can be used as the solid fuel.

[0014] The boiler 10 has a furnace 11, a combustion device 20, and a combustion gas passage 12. The furnace 11 has a hollow rectangular shape and is installed along the vertical direction. The furnace wall 101 that constitutes the inner wall surface of the furnace 11 is composed of a plurality of heat transfer tubes and fins that connect the heat transfer tubes to each other, and recovers the heat generated by the combustion of pulverized fuel by heat exchange with water or steam circulating inside the heat transfer tubes, while also suppressing the temperature rise of the furnace wall 101.

[0015] The combustion device 20 is installed in the lower region of the furnace 11. In this embodiment, the combustion device 20 has a plurality of burners 21A, 21B, 21C, 21D, 21E, and 21F (hereinafter sometimes collectively referred to as "burners 21") mounted on the furnace wall 101. The burners 21 are arranged in multiple rows along the vertical direction, with each set consisting of four burners arranged at equal intervals along the circumferential direction of the furnace 11 (for example, four burners installed at each corner of a rectangular furnace 11). In Figure 1, for illustrative purposes, only two burners from one set are shown, and each set is labeled with reference numerals 21A, 21B, 21C, 21D, 21E, and 21F. The shape of the furnace, the number of burner rows, the number of burners in each row, and the arrangement of the burners are not limited to this embodiment.

[0016] Burners 21A, 21B, 21C, 21D, 21E, and 21F are each connected to multiple mills 31A, 31B, 31C, 31D, 31E, and 31F (hereinafter sometimes collectively referred to as "mills 31") via multiple fine fuel supply pipes 22A, 22B, 22C, 22D, 22E, and 22F (hereinafter sometimes collectively referred to as "fine fuel supply pipes 22"). Mills 31 crush solid fuel to produce fine fuel, and are, for example, vertical roller mills configured such that a crushing table (not shown) is supported inside so as to be rotatable, and multiple 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) equipped in mill 31 by primary air (conveying gas, oxidizing gas) supplied to mill 31. In the classifier, the crushed solid fuel is classified into fine fuel particles with a particle size suitable for combustion in the burner 21 and coarse fuel particles with a particle size larger than that. The fine fuel particles that pass through the classifier are supplied to the burner 21 via the fine fuel supply pipe 22 along with primary air. The coarse fuel particles that do not pass through the classifier fall onto the crushing table inside the mill 31 due to their own weight and are crushed again.

[0017] At least a portion of burners 21A, 21B, 21C, 21D, 21E, and 21F are designed to exclusively burn pulverized solid fuels such as pulverized coal, biomass, or oil coke, or ammonia fuel, or oil fuels such as heavy oil (liquid fuels), or to co-fire a combination of these various fuels. The specific structure of the burners will be explained later using Figure 2 and subsequent figures. When using ammonia fuel (fuel containing ammonia as a component), the ammonia fuel is supplied from the ammonia supply source 50. The ammonia fuel may be gaseous or liquid.

[0018] Furthermore, above the mounting position of the burner 21 in the furnace 11, a plurality of additional air ports (AA ports) 25 are provided for supplying additional combustion air (AA) into the furnace 11. The ends of additional air ducts (AA ducts) 26, which branch off from the air duct 24, are connected to the additional air ports 25, and a portion of the air supplied from the forced draft fan 32 can be supplied to the additional air ports 25 as additional combustion air via the additional air ducts 26.

[0019] An air register 23 is provided on the outside of the furnace 11 where the burner 21 is installed, and one end of an air duct 24 is connected to this air register 23. A forced draft fan (FDF) 32 is connected to 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 (details will be described later), and is supplied to the burner 21 as secondary air (combustion air, oxidizing gas) via the air register 23 and introduced into the furnace 11.

[0020] 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 (hereinafter sometimes collectively referred to as "superheater 102"), reheaters 103A, 103B (hereinafter 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 feedwater or steam circulating inside each heat exchanger. Note that the arrangement and shape of each heat exchanger are not limited to the configuration shown in Figure 1.

[0021] Downstream of the combustion gas passage 12 is a flue 13 through which the combustion gas, whose heat has been recovered by the heat exchanger, is discharged. An air preheater (air heater) 42 is installed between the flue 13 and the air duct 24, and heat exchange occurs between the air flowing through the air duct 24 and the combustion gas flowing through the flue 13. By heating the primary air supplied to the mill 31 and the secondary air supplied to the burner 21, heat is further recovered from the combustion gas after heat exchange with water or steam.

[0022] Furthermore, a denitrification device 43 may be provided in the flue 13 at a position upstream of the air preheater 42. 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, and removes and reduces nitrogen oxides in the combustion gas by promoting the reaction between the nitrogen oxides (NOx) in the combustion gas to which the reducing agent has been supplied and the reducing agent through the catalytic action of a denitrification catalyst installed in the denitrification device 43.

[0023] 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 outside the system as exhaust gas.

[0024] In the boiler 10, when multiple mills 31 are driven, the crushed and classified pulverized fuel is supplied to the burner 21 via the pulverized fuel supply pipe 22 along with primary air. In addition, secondary air heated by the air preheater 42 is supplied to the burner 21 from the air duct 24 via the wind box 23. The burner 21 blows a pulverized fuel mixture, which is a mixture of pulverized fuel and primary air, into the furnace 11, and also blows secondary air into the furnace 11. The pulverized fuel mixture blown into the furnace 11 ignites and reacts with the secondary air to form a flame. The flame is formed in the lower region of the furnace 11, and the high-temperature combustion gas rises inside the furnace 11 and flows into the combustion gas passage 12. 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, and stable combustion in the furnace 11 can be achieved by adjusting the ratio of oxygen to the supplied fuel amount to an appropriate range.

[0025] The combustion gas flowing into the combustion gas passage 12 undergoes heat exchange with water and 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 heat exchange 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 through 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.

[0026] The boiler 10 is equipped with an ammonia supply source 50. The ammonia supply source 50 stores ammonia fuel. The ammonia fuel is supplied from the ammonia supply source 50 to each burner 21.

[0027] The control unit controls the operation of the boiler 10 and consists of, for example, a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), and a computer-readable storage medium. A series of processes for realizing various functions are stored in the storage medium in the form of a program, for example. The CPU reads this program into the RAM and performs information processing and calculations to realize the various functions. The program may be pre-installed on the ROM or other storage medium, provided in a state where it is stored on a computer-readable storage medium, or distributed via wired or wireless communication means. Computer-readable storage media include magnetic disks, magneto-optical disks, CD-ROMs, DVD-ROMs, semiconductor memory, etc.

[0028] Figure 2 schematically shows a longitudinal section of the burner 21 in Figure 1. In Figure 2, the top indicates the vertical upward direction, and the bottom indicates the vertical downward direction.

[0029] The burner 21 is capable of co-firing ammonia fuel and pulverized fuel, as well as exclusively firing ammonia fuel or exclusively firing pulverized fuel. The burner 21 includes an oil fuel nozzle 61 extending along a central axis (axis) CL, and a fuel nozzle 62 provided to cover the oil fuel nozzle 61. Each nozzle 61 and 62 has a common central axis CL, and for example, has a circular cross-section and is made of metal.

[0030] The oil fuel nozzle 61 is supplied with oil fuel and injects it into the furnace 11. The tip of the oil fuel nozzle 61 is provided with an injection tip (not shown) that atomizes the oil fuel. The oil fuel is supplied from an oil fuel supply source (not shown) and is used when starting the burner 21. When gas fuel is used as the starting fuel, a gas fuel nozzle that injects gas fuel may be provided instead of the oil fuel nozzle 61. Furthermore, the oil fuel nozzle 61 can be omitted in this disclosure.

[0031] When used as a pulverized coal burner, pulverized coal (pulverized fuel) and primary air (oxidizing gas) are supplied to the fuel nozzle 62. Upstream of the fuel nozzle 62, a pulverized fuel supply pipe (fuel gas inlet) 22 is connected to supply a combustible mixture (hereinafter referred to as "fuel gas") which is a mixture of pulverized fuel and primary air. The pulverized fuel supply pipe 22 is connected in an intersecting direction A1 that intersects the central axis CL. Thus, the fuel gas supplied from the pulverized fuel supply pipe 22 is supplied from a direction inclined with respect to the central axis CL (intersecting direction A1).

[0032] As shown in Figure 2, a flame holder 71 is provided at the tip and outer circumference of the fuel nozzle 62. The flame holder 71 is ring-shaped when viewed from the front of the fuel nozzle 62. The flame holder 71 partially obstructs the flow of secondary air through the secondary air passage 73, forming a flame-holding region downstream of it.

[0033] A secondary air nozzle 72 is provided on the outer circumference of the fuel nozzle 62. The secondary air nozzle 72 forms a secondary air passage 73. The secondary air passage 73 is provided so as to cover the fuel nozzle 62. An enlarged guide sleeve 72a is provided at the tip of the secondary air nozzle 72.

[0034] A tertiary air passage 74 is provided on the outer periphery of the secondary air passage 73 so as to cover the secondary air passage 73. A swivel device 74a is provided within the tertiary air passage 74 to impart a swirling motion to the tertiary air. In this disclosure, the swivel device 74a may be omitted.

[0035] Multiple ammonia nozzles 80 are provided, extending from within the tertiary air passage 74 and through the guide sleeve 72a. Each ammonia nozzle 80 is tubular and is located on the outer circumference of the fuel nozzle 62 and in a position corresponding to the tertiary air passage 74. The tip of each ammonia nozzle 80 is provided with an injection tip (not shown) with an injection hole, so that ammonia fuel is sprayed into the furnace 11.

[0036] As shown in Figure 3, multiple ammonia nozzles 80 are arranged on a concentric circle C1 centered on the central axis CL, and inject liquid ammonia fuel supplied from the ammonia supply source 50 (see Figure 1) into the furnace 11. Upstream of each ammonia nozzle 80, an ammonia fuel switching valve is provided and controlled by the control unit.

[0037] As shown in Figure 3, the intersecting direction A1, which is the direction in which fuel gas is supplied from the fine fuel supply pipe 22 to the fuel nozzle 62, can be supplied not only from vertically downwards when the burner 21 is viewed from the front, but also from a direction inclined from the vertical. The intersecting direction A1 changes depending on the fixed position of the burner 21 relative to the furnace 11.

[0038] The ammonia nozzles 80 are not arranged at equal angular intervals on a concentric circle C1, but rather are arranged unevenly so that the number density of ammonia nozzles 80 is higher in the region opposite to the intersecting direction A1 in which fuel gas is introduced relative to the central axis CL. Specifically, if the region downstream (far side) of the intersecting direction A1 from a dividing line L1 that is perpendicular to the intersecting direction A1 and passes through the central axis CL is designated as the anti-fuel gas introduction region AR1, and the region upstream (near side) of the intersecting direction A1 from the dividing line L1 is designated as the fuel gas introduction region AR2, then the anti-fuel gas introduction region AR1 has more ammonia nozzles 80 than the fuel gas introduction region AR2. As a result, if the area of ​​the injection holes of the ammonia nozzles 80 is assumed to be the same, the total area of ​​the injection holes of each ammonia nozzle 80 in the anti-fuel gas introduction region AR1 will be larger than the total area of ​​the injection holes of each ammonia nozzle 80 in the fuel gas introduction region AR2.

[0039] As shown in Figure 3, the ammonia nozzle 80 may not be provided on the upstream (near) side of the intersecting direction A1. This avoids interference between the pulverized fuel supply pipe 22 and the ammonia nozzle 80.

[0040] Furthermore, the number of ammonia nozzles 80 is not limited to the eight shown in Figure 3; it may be seven or fewer, or nine or more.

[0041] With the burner 21 configured as described above, the fine fuel and ammonia fuel are co-fired as follows. Oil fuel is supplied to the oil fuel nozzle 61 only at startup, and a startup flame is formed. After startup, the supply of oil fuel to the oil fuel nozzle 61 is stopped. Then, as shown in Figure 2, a fuel gas, which is a mixed fluid of fine fuel and primary air, is supplied between the fuel nozzle 62 and the oil fuel nozzle 61, and ammonia fuel is supplied from the ammonia nozzle 80, forming a flame in the furnace 11.

[0042] The operation and effects of the present embodiment described above are as follows. The fuel gas introduced from the fine powder fuel supply pipe 22 toward the fuel nozzle 62 is introduced from the intersection direction A1 that intersects the central axis CL. Therefore, due to the difference in inertial forces between the fine powder fuel and air, fuel gas with a high fuel concentration is introduced into the furnace 11 from the anti-fuel gas introduction region AR1, which is the region on the downstream side of the intersection direction A1 with respect to the central axis CL, that is, on the opposite side of the fine powder fuel supply pipe 22 with respect to the central axis CL. In the flame in the region with a high fuel concentration, oxygen deficiency occurs and a reduction region is formed. By increasing the amount of ammonia fuel supplied to this reduction region, the reduction reaction in the reduction region can be strengthened, and NOx generation can be suppressed.

[0043] The total number of injection holes for injecting ammonia from each ammonia nozzle 80 is set such that the amount of ammonia injected from the anti-fuel gas introduction region AR1 is larger than the amount of ammonia injected from the fuel gas introduction region AR2. Thereby, by making the hole diameters of each ammonia nozzle 80 the same and arranging the ammonia nozzles 80 around the central axis CL unevenly, the supply amount of ammonia fuel can be adjusted.

[0044] In the above-described embodiment, the amount of ammonia in the anti-fuel gas introduction region AR1 is increased by arranging the ammonia nozzles 80 unevenly around the central axis CL, but it is not limited to this. For example, even when the ammonia nozzles 80 are arranged evenly around the central axis CL, the injection hole areas of each ammonia nozzle 80 are made different, and the total area of the injection holes is used to make the amount of ammonia injected from the anti-fuel gas introduction region AR1 larger than the amount of ammonia injected from the fuel gas introduction region AR2.

[0045] Also, a flow rate adjustment valve for adjusting the flow rate of ammonia fuel may be provided upstream of at least one ammonia nozzle 80, and the flow rate adjustment valve may be controlled by a control unit. Thereby, the amount of ammonia injected from the anti-fuel gas introduction region AR1 can be made larger than the amount of ammonia injected from the fuel gas introduction region AR2.

[0046] In addition, in the above-described embodiments, the co-firing of fine powder fuel and ammonia fuel has been described as a premise. However, the configuration of this embodiment is also effective for exclusive firing of ammonia. That is, in the flow of air supplied to the fuel nozzle 62 via the fine powder fuel supply pipe 22 and introduced into the furnace 11, the anti-fuel gas introduction region AR1 has a higher air flow velocity or flow rate than the fuel gas introduction region AR2. Therefore, it is preferable to flow a large amount of ammonia fuel into the anti-fuel gas introduction region AR1.

[0047] The burner described in each of the embodiments described above can be understood as follows, for example.

[0048] The burner (21) according to the first aspect of the present disclosure extends in the direction of the axis (CL), and includes a fuel nozzle (62) that blows a fuel gas obtained by mixing fuel and an oxidizing gas into a furnace, a fuel gas introduction portion (22) that introduces fuel gas into the fuel nozzle (62) from an intersection direction (A1) intersecting the axis (CL), and a plurality of ammonia nozzles (80) disposed around the axis (CL) and capable of supplying ammonia fuel into the furnace (11). The amount of ammonia fuel supplied from each ammonia nozzle (80) is larger in the anti-fuel gas introduction region (AR1) located on the opposite side of the fuel gas introduction portion (22) with respect to the axis (CL) than in the fuel gas introduction region (AR2) where the fuel gas introduction portion (22) is located with respect to the axis (CL).

[0049] The fuel gas introduced from the fuel gas inlet towards the fuel nozzle is introduced from a direction intersecting the axis. Therefore, due to the difference in inertial force between the fuel and the oxidizing gas, fuel gas with a higher concentration is introduced into the furnace from the region downstream of the axis in the direction intersecting the axis, i.e., the anti-fuel gas inlet region located on the opposite side of the fuel gas inlet relative to the axis. In the flame of the high-fuel-concentration region, oxygen becomes deficient and a reduction region is formed. By increasing the amount of ammonia fuel supplied to this reduction region, the reduction reaction in the reduction region can be strengthened, and NOx generation can be suppressed. Furthermore, even when ammonia combustion is performed by flowing only oxidizing gas to the fuel nozzle without supplying fuel (in the case of ammonia-only combustion), it is preferable to flow a large amount of ammonia fuel into the anti-fuel gas inlet region because the flow velocity or flow rate of the oxidizing gas is greater in the anti-fuel gas inlet region than in the fuel gas inlet region.

[0050] In the second aspect of the present disclosure, the burner (21) is such that, in the first aspect, the total number of injection holes of each ammonia nozzle (80) in the anti-fuel gas introduction region (AR1) is greater than the total number of injection holes of each ammonia nozzle (80) in the fuel gas introduction region (AR2).

[0051] The total number of injection holes from each ammonia nozzle allows the amount of ammonia injected from the anti-fuel gas introduction area to be greater than the amount injected from the fuel gas introduction area. This also allows for adjustment of the ammonia fuel supply by making the hole diameter of each ammonia nozzle the same and arranging the ammonia nozzles unevenly around the axis.

[0052] In the third aspect of the present disclosure, the burner (21) is such that, in the first or second aspect, the total area of ​​the injection holes of each ammonia nozzle (80) in the anti-fuel gas introduction region (AR1) is greater than the total area of ​​the injection holes of each ammonia nozzle (80) in the fuel gas introduction region (AR2).

[0053] The total area of ​​the injection holes from which ammonia is injected from each ammonia nozzle can make the amount of ammonia injected from the anti-fuel gas introduction region greater than the amount of ammonia injected from the fuel gas introduction region.

[0054] A burner (21) according to a fourth aspect of the present disclosure, in any of the first to third aspects, wherein at least one of the ammonia nozzles (80) is equipped with a flow control valve for adjusting the flow rate of ammonia fuel.

[0055] By providing a flow control valve in the ammonia nozzle, the amount of ammonia injected from the anti-fuel gas introduction region can be made greater than the amount of ammonia injected from the fuel gas introduction region. This makes it possible to adjust the supply amount of ammonia fuel even when the hole diameter of each ammonia nozzle is the same and the ammonia nozzles arranged around the axis are evenly spaced.

[0056] 10 Boiler 11 Furnace 12 Combustion gas passage 13 Flue 20 Combustion apparatus 21 Burner 22 Fine fuel supply pipe (fuel gas inlet) 23 Wind box 24 Air duct 25 Additional air port 26 Additional air duct 31 Mill 32 Forced draft fan 41 Gas duct 42 Air preheater 43 Denitrification apparatus 44 Apparatus 46 Desulfurization apparatus 47 Chimney 50 Ammonia supply source 61 Oil fuel nozzle 62 Fuel nozzle 71 Flame holder 72 Secondary air nozzle 72a Guide sleeve 73 Secondary air passage 74 Tertiary air passage 74a Swivel 80 Ammonia nozzle A1 Intersecting direction AR1 Anti-fuel gas inlet area AR2 Fuel gas inlet area CL Central axis (axis) C1 Concentric circles L1 dividing line

Claims

1. A burner comprising: a fuel nozzle extending in the direction of an axis and injecting a fuel gas mixture of fuel and an oxidizing gas into the furnace; a fuel gas introduction section introducing the fuel gas into the fuel nozzle from a direction intersecting the axis; and a plurality of ammonia nozzles arranged around the axis and capable of supplying ammonia fuel into the furnace, wherein the amount of ammonia fuel supplied from each ammonia nozzle is greater in the anti-fuel gas introduction region located on the opposite side of the axis from the fuel gas introduction section than in the fuel gas introduction region located on the axis.

2. The burner according to claim 1, wherein the total number of injection holes of each ammonia nozzle in the anti-fuel gas introduction region is greater than the total number of injection holes of each ammonia nozzle in the fuel gas introduction region.

3. The burner according to claim 1, wherein the total area of ​​the injection holes of each ammonia nozzle in the anti-fuel gas introduction region is greater than the total area of ​​the injection holes of each ammonia nozzle in the fuel gas introduction region.

4. The burner according to claim 1, wherein at least one of the ammonia nozzles is equipped with a flow control valve for adjusting the flow rate of ammonia fuel.

Images