Burner, boiler equipped with same, and burner operating method

Abstract

Provided is a burner capable of exclusively burning a pulverized fuel and capable of exclusively burning an ammonia fuel. The burner comprises: an inner tube nozzle (61) that extends along a center axial line (CL) and that supplies a liquid ammonia fuel or an oil fuel into a furnace; a first flame holder (67) that holds a flame of the liquid ammonia fuel or oil fuel supplied from the inner tube nozzle (61); an outer tube nozzle (62) that is provided so as to extend along the center axial line (CL) and cover the inner tube nozzle (61), and that supplies the pulverized fuel and / or a primary air into the furnace (11); and a second flame holder (71) that holds a flame of the pulverized fuel supplied from the outer tube nozzle (62). The inner tube nozzle (61) comprises a fuel injection tip in which are formed: an ammonia flow channel in which the liquid ammonia fuel flows; and an oil flow channel in which the oil fuel flows and which constitutes a separate system from the ammonia flow channel.

Description

[Technical Field]

[0001] The present disclosure relates to a burner that burns pulverized fuel, for example, obtained by pulverizing solid fuel, and ammonia fuel, a boiler including the burner, and a method for operating the burner. [Background technology]

[0002] Large boilers, such as power generation boilers, have a hollow furnace installed vertically, with multiple burners disposed on the furnace wall. Large boilers also have a flue connected vertically above the furnace, with a heat exchanger disposed in the flue for generating steam. The burner injects a mixture of fuel and air (oxidizing gas) into the furnace, forming a flame, generating combustion gas that flows down the flue. A heat exchanger is installed in the area where the combustion gas flows, and superheated steam is generated by heating water or steam flowing through the heat transfer tubes that make up the heat exchanger.

[0003] For burners used in boilers, studies are being conducted to perform mixed combustion of pulverized coal and ammonia fuel, or to perform single combustion of pulverized coal and single combustion of ammonia fuel (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2020-41748 Summary of the Invention [Problem to be solved by the invention]

[0005] However, Patent Document 1 assumes that ammonia fuel is supplied as a gas, and does not consider using it as a liquid. Therefore, even if gas is used as ammonia fuel, a sufficient calorific value cannot be secured and it cannot be put into practical use as ammonia mono-combustion. Even if liquid ammonia fuel as disclosed in Patent Document 1 is used, there is a problem in that the flame temperature is lowered due to the heat of vaporization, resulting in a decrease in flame stability.

[0006] The present disclosure has been made in consideration of the above circumstances, and aims to provide a burner that is capable of exclusively burning pulverized fuel and exclusively burning ammonia fuel, a boiler equipped with the same, and a method for operating the burner. [Means for solving the problem]

[0007] A burner according to one embodiment of the present disclosure comprises: an inner cylindrical nozzle extending along a central axis and supplying liquid ammonia fuel or oil fuel into a furnace; a first flame stabilizer that stabilizes the flame of the liquid ammonia fuel or oil fuel supplied from the inner cylindrical nozzle; an outer cylindrical nozzle extending along the central axis and arranged to cover the inner cylindrical nozzle and supplying pulverized fuel and / or primary air into the furnace; and a second flame stabilizer that stabilizes the flame of the pulverized fuel supplied from the outer cylindrical nozzle, and the inner cylindrical nozzle comprises a fuel injection tip formed with an ammonia flow path through which the liquid ammonia fuel flows and an oil flow path through which the oil fuel flows, the oil flow path being a system separate from the ammonia flow path.

[0008] A burner according to one aspect of the present disclosure comprises an inner cylindrical nozzle extending along a central axis and supplying oil fuel into a furnace, an outer cylindrical nozzle extending along the central axis and arranged to cover the inner cylindrical nozzle and supplying pulverized fuel and / or primary air into the furnace, a flame stabilizer that stabilizes the flame of the pulverized fuel supplied from the outer cylindrical nozzle, and a liquid ammonia nozzle that supplies liquid ammonia fuel into the furnace, the liquid ammonia nozzle comprising a liquid ammonia injection tip that injects the liquid ammonia fuel.

[0009] A method for operating a burner according to one aspect of the present disclosure includes an inner cylindrical nozzle extending along a central axis and supplying liquid ammonia fuel or oil fuel into a furnace, a first flame stabilizer for stabilizing a flame of the liquid ammonia fuel or oil fuel supplied from the inner cylindrical nozzle, an outer cylindrical nozzle extending along the central axis and provided so as to cover the inner cylindrical nozzle and supplying pulverized fuel and / or primary air into the furnace, and a second flame stabilizer for stabilizing the flame of the pulverized fuel supplied from the outer cylindrical nozzle, wherein the inner cylindrical nozzle has an ammonia flow path through which the liquid ammonia fuel flows and an ammonia flow path separate from the ammonia flow path. The method for operating a burner is provided with a fuel injection tip having an oil flow path formed therein through which the oil fuel flows, the method comprising: a start-up step of starting the burner by supplying oil fuel to the oil flow path of the fuel injection tip; an ammonia mono-combustion step of performing ammonia mono-combustion by supplying liquid ammonia fuel to the ammonia flow path of the fuel injection tip without supplying the pulverized fuel to the outer cylindrical nozzle; and a pulverized fuel mono-combustion step of performing pulverized fuel mono-combustion by supplying the pulverized fuel and the primary air to the outer cylindrical nozzle without supplying liquid ammonia fuel to the ammonia flow path of the fuel injection tip.

[0010] A method for operating a burner according to one aspect of the present disclosure is a method for operating a burner comprising: an inner cylindrical nozzle extending along a central axis and supplying oil fuel into a furnace; an outer cylindrical nozzle extending along the central axis and arranged to cover the inner cylindrical nozzle and supplying pulverized fuel and / or primary air into the furnace; a flame stabilizer that stabilizes the flame of the pulverized fuel supplied from the outer cylindrical nozzle; and a liquid ammonia nozzle that supplies liquid ammonia fuel into the furnace, wherein the liquid ammonia nozzle is equipped with a liquid ammonia injection tip that injects the liquid ammonia fuel. The method includes a start-up step of supplying oil fuel to the inner cylindrical nozzle to start the burner; an ammonia mono-combustion step of supplying liquid ammonia fuel to the liquid ammonia injection tip of the liquid ammonia nozzle without supplying the pulverized fuel to the outer cylindrical nozzle to perform ammonia mono-combustion; and a pulverized fuel mono-combustion step of supplying the pulverized fuel and the primary air to the outer cylindrical nozzle without supplying liquid ammonia fuel to the liquid ammonia injection tip to perform pulverized fuel mono-combustion. [Effects of the Invention]

[0011] The burner of the present disclosure allows for both exclusive combustion of pulverized fuel and exclusive combustion of ammonia fuel. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a schematic configuration diagram showing a boiler according to a first embodiment of the present disclosure. [Figure 2A] FIG. 2 is a vertical cross-sectional view showing the burner of FIG. [Figure 2B] 2B is a longitudinal cross-sectional view of a fuel injection tip used in the burner of FIG. 2A. FIG. [Figure 3] FIG. 4 is a vertical cross-sectional view showing a burner according to a second embodiment of the present disclosure. [Figure 4A] FIG. 10 is a vertical cross-sectional view showing a burner according to a third embodiment of the present disclosure. [Figure 4B] 4B is a longitudinal cross-sectional view showing a fuel injection tip used in the burner of FIG. 4A. FIG. [Figure 5] FIG. 10 is a vertical cross-sectional view showing a burner according to a fourth embodiment of the present disclosure. [Figure 6] FIG. 6 is a vertical cross-sectional view showing the burner shown in FIG. 5 when pulverized coal is burned exclusively. [Figure 7] FIG. 6 is a vertical cross-sectional view showing the burner shown in FIG. 5 when liquid ammonia is burned exclusively. [Figure 8] FIG. 10 is a vertical cross-sectional view showing a burner of a comparative example. [Figure 9] FIG. 8 is a vertical cross-sectional view of a burner showing a modification of the burner shown in FIG. 7 when burning liquid ammonia exclusively. [Figure 10] FIG. 8 is a vertical cross-sectional view of the burner showing another modified example when burning liquid ammonia as shown in FIG. 7. DETAILED DESCRIPTION OF THE INVENTION

[0013] An embodiment of the present disclosure will be described below with reference to the drawings. Note that the present invention is not limited to this embodiment, and when there are multiple embodiments, it also includes configurations that combine the embodiments. In the following description, "up" and "upper" refer to the upper side in the vertical direction, and "lower" and "lower" refer to the lower side in the vertical direction, and the vertical direction is not precise and may include errors.

[0014] [First embodiment] FIG. 1 shows a boiler 10 of this embodiment that uses pulverized fuel and / or ammonia (NH3) fuel as its main fuel. The boiler 10 of this embodiment is a boiler that can burn pulverized solid fuel and liquid ammonia fuel using a burner, and exchange the heat generated by this combustion with feedwater or steam to generate superheated steam. Biomass fuel, coal, etc. are used as solid fuel.

[0015] The boiler 10 has a furnace 11, a combustion device 20, and a combustion gas passage 12. The furnace 11 has a hollow rectangular cylindrical shape and is installed vertically. The furnace wall 101 that forms 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 together, and recovers the heat generated by the combustion of pulverized fuel by heat exchange with water and steam circulating inside the heat transfer tubes, while suppressing the temperature rise of the furnace wall 101.

[0016] 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, when these burners are not to be distinguished, they will be simply referred to as "burners 21") attached to the furnace wall 101. The burners 21 are arranged at equal intervals in the furnace width direction along the furnace wall 101 (for example, they are arranged in the furnace width direction so as to face each other on the opposing furnace walls 101 for opposed combustion), and are arranged in multiple stages along the vertical direction. The shape of the furnace, the number of burner stages, the number of burners per stage, the arrangement of the burners, etc. are not limited to this embodiment.

[0017] Burners 21A, 21B, 21C, 21D, 21E, and 21F are connected to a plurality of mills (pulverizers) 31A, 31B, 31C, 31D, 31E, and 31F (hereinafter, when these mills are not distinguished, they will be simply referred to as "mills 31") via a plurality of pulverized fuel supply pipes 22A, 22B, 22C, 22D, 22E, and 22F, respectively (hereinafter, when these mills are not distinguished, they will be simply referred to as "mills 31"). Mill 31 is, for example, a vertical roller mill having a rotatable grinding table (not shown) supported therein and a plurality of grinding rollers (not shown) supported above the grinding table so that they can rotate in conjunction with the rotation of the grinding table. The solid fuel pulverized by the cooperation of the grinding rollers and the grinding table is transported to a classifier (not shown) provided in mill 31 by primary air (carrier gas, oxidizing gas) supplied to mill 31. The classifier separates the pulverized fuel into pulverized fuel having a particle size smaller than that suitable for combustion in the burner 21 and coarse pulverized fuel having a particle size larger than that. The pulverized fuel passes through the classifier and is supplied to the burner 21 together with primary air via the pulverized fuel supply pipe 22. The coarse pulverized fuel that does not pass through the classifier falls onto the grinding table inside the mill 31 under its own weight and is re-ground.

[0018] An air register 23 is provided outside the furnace 11 at the installation position of the burner 21, and one end of an air duct 24 is connected to the 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 and is supplied to the burner 21 via the air register 23 as secondary air (combustion air, oxidizing gas) and introduced into the furnace 11.

[0019] The combustion gas passage 12 is connected to the vertical upper part of the furnace 11. The combustion gas passage 12 is provided with superheaters 102A, 102B, and 102C (hereinafter, when there is no need to distinguish between these superheaters, they will simply be referred to as "superheaters 102"), reheaters 103A and 103B (hereinafter, when there is no need to distinguish between these reheaters, they will simply be referred to as "reheater 103"), and a coal economizer 104 as heat exchangers for recovering heat from the combustion gas, and heat is exchanged between the combustion gas generated in the furnace 11 and feedwater or steam circulating inside each heat exchanger. Note that the arrangement and shape of each heat exchanger are not limited to those shown in FIG. 1.

[0020] A flue 13 is connected to the downstream side of the combustion gas passage 12, and discharges the combustion gas whose heat has been recovered by the heat exchanger. An air preheater (air heater) 42 is provided between the flue 13 and the air duct 24, and heat is exchanged between the air flowing through the air duct 24 and the combustion gas flowing through the flue 13, heating the primary air supplied to the mill 31 and the secondary air supplied to the burner 21, thereby recovering further heat from the combustion gas after heat exchange with water and steam.

[0021] Furthermore, a denitration device 43 may be provided in the flue 13 at a position upstream of the air preheater 42. The denitration device 43 supplies a reducing agent, such as ammonia or urea water, which has the effect of reducing nitrogen oxides, to the combustion gas flowing through the flue 13, and promotes the reaction between the nitrogen oxides (NOx) in the combustion gas to which the reducing agent has been supplied and the reducing agent by the catalytic action of a denitration catalyst provided in the denitration device 43, thereby removing and reducing the nitrogen oxides in the combustion gas. A gas duct 41 is connected to the flue 13 downstream of the air preheater 42. The gas duct 41 is provided with environmental equipment such as a dust collector 44, such as an electrostatic precipitator, that removes ash and the like from the combustion gas, and a desulfurization equipment 46 that removes sulfur oxides, as well as an induced draft fan (IDF) 45 that guides the exhaust gas to these environmental equipment. The downstream end of the gas duct 41 is connected to a chimney 47, and the combustion gas that has been treated in the environmental equipment is discharged to the outside of the system as exhaust gas.

[0022] When the boiler 10 is performing mono-combustion of pulverized fuel (or co-combustion with ammonia fuel), the multiple mills 31 are driven, and pulverized and classified pulverized fuel is supplied to the burner 21 together with primary air via the pulverized fuel supply pipe 22. 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. A flame is formed in the lower region of the furnace 11, and high-temperature combustion gas rises within 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 the oxidizing gas may have a higher or lower oxygen content than air, and stable combustion can be achieved in the furnace 11 by adjusting the ratio of the amount of oxygen to the amount of fuel supplied within an appropriate range.

[0023] Additionally, above the mounting position of the burners 21 in the furnace 11, a plurality of additional air ports (AA ports) 25 are provided for supplying additional air for combustion (AA) into the furnace 11. The additional air ports 25 are connected to the ends of additional air ducts (AA ducts) 26 branching off from the air duct 24, and a portion of the air supplied from the forced draft fan 32 can be supplied to the additional air ports 25 via the additional air ducts 26 as additional air for combustion.

[0024] In region A (corresponding to the installation range of the wind box 23 in the height direction) inside the furnace 11 shown in Fig. 1, a flame is formed by combustion of a mixture of primary air and pulverized fuel with secondary air. Here, the air ratio in region A is set to be 1 or less, specifically, the amount of air supplied to the burner 21 (the total amount of primary air and secondary air) is set to be less than the theoretical amount of air relative to the amount of fuel supplied to the burner 21. By doing so, regions A and B (regions between the top of the burner 21 and the bottom of the additional air port 25) inside the furnace 11 become reducing atmospheres, and nitrogen oxides (NOx) generated by combustion are reduced inside the furnace 11. Thereafter, in region C (region above the bottom of the additional air port 25), additional combustion air is supplied from the additional air port 25 to the combustion gas in which NOx has been reduced, completing the combustion. However, the amount of NOx generated is reduced by the reduction effect in regions A and B.

[0025] The combustion gas that has flowed into the combustion gas passage 12 exchanges heat with water and steam in a superheater 102, a reheater 103, and an economizer 104 arranged inside the combustion gas passage 12, and is then discharged into the flue 13, where nitrogen oxides are removed in a denitration device 43, and the gas exchanges heat with primary air and secondary air in an air preheater 42, and is then discharged into the gas duct 41, where ash and the like are removed in a dust collector 44, and sulfur oxides are removed in a desulfurization device 46, and the gas is then discharged to the outside of the system from a chimney 47. Note that the arrangement of the heat exchangers in the combustion gas passage 12 and the arrangement of the devices from the flue 13 to the gas duct 41 with respect to the combustion gas flow do not necessarily have to be in the order described above.

[0026] The boiler 10 is provided with a liquid ammonia supply source 50. Ammonia is stored in liquid form as an ammonia fuel in the liquid ammonia supply source 50. The liquid ammonia is supplied from the liquid ammonia supply source 50 to each burner 21.

[0027] The switching between the pulverized fuel and the ammonia fuel may be performed manually by an operator, or may be performed by a command from a control unit. The control unit is composed of, for example, a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), and computer-readable storage media. A series of processes for realizing various functions is stored in, for example, a storage medium in the form of a program. The CPU reads this program into RAM and executes information processing and arithmetic operations to realize various functions. The program may be pre-installed in a ROM or other storage medium, provided in a state stored in a computer-readable storage medium, or distributed via wired or wireless communication means. Examples of computer-readable storage media include magnetic disks, magneto-optical disks, CD-ROMs, DVD-ROMs, and semiconductor memories.

[0028] 2A shows a burner 21. The burner 21 is capable of firing both pulverized fuel and liquid ammonia fuel. The burner 21 includes an inner cylindrical nozzle 61 extending along a central axis CL, and an outer cylindrical nozzle 62 provided to cover the inner cylindrical nozzle 61. A core air nozzle 63 is provided on the outer circumferential side of the inner cylindrical nozzle 61 and on the inner circumferential side of the outer cylindrical nozzle 62. Each of the nozzles 61, 62, 63 has a common central axis CL, has a circular cross section, for example, and is made of metal.

[0029] The inner cylinder nozzle 61 is supplied with oil fuel and liquid ammonia fuel, and injects these fuels into the furnace 11. The liquid ammonia fuel is supplied from the liquid ammonia supply source 50 shown in Fig. 1. The oil fuel is supplied from an oil fuel supply source (not shown) and is used when the burner 21 is started up.

[0030] A fuel injection tip 65 (see FIG. 2B) is provided inside the inner cylindrical nozzle 61. The fuel injection tip 65 is a two-fluid nozzle. 2B, the fuel injection tip 65 is formed with a gas flow path 65a in the center, a plurality of oil fuel flow paths 65b on the outer periphery thereof, and a plurality of liquid ammonia fuel flow paths 65c on the outer periphery thereof. Pressurized steam or air for atomizing the oil fuel and liquid ammonia fuel flows through the gas flow path 65a. The gas flow path 65a is connected to a plurality of first branch flow paths 65a1 connected to the liquid ammonia fuel flow path 65c, and a second branch flow path 65a2 connected to the oil fuel flow path 65b. The liquid ammonia fuel and oil fuel are atomized by the gas supplied from these branch flow paths 65a1 and 65a2 and supplied into the furnace 11. An oil fuel supply source is connected to the upstream side of the oil fuel flow path 65b, and the opening / closing and opening degree of the oil fuel valves are adjusted by one or more oil fuel valves (not shown). The oil fuel valves can be controlled by a control unit. The liquid ammonia supply source 50 (see FIG. 1) is connected to the upstream side of the liquid ammonia fuel flow path 65c, and the opening / closing and opening degree thereof are adjusted by one or more liquid ammonia fuel valves (not shown). The liquid ammonia fuel valves can be controlled by a control unit. The fuel injection tip 65 having the above-described configuration makes it possible to selectively inject liquid ammonia fuel and oil fuel.

[0031] 2A, a first flame stabilizer 67 is provided on the outer periphery of the tip of the inner cylinder nozzle 61, between it and the core air nozzle 63. The first flame stabilizer 67 is, for example, shaped like a vane, and imparts a swirl about the central axis CL to core air (central air) serving as combustion air flowing through the core air nozzle 63. The first flame stabilizer 67 stabilizes the flame of the liquid ammonia fuel injected from the inner cylinder nozzle 61.

[0032] Pulverized fuel and primary air introduced from the mill 31 (see FIG. 1) are supplied into the outer cylindrical nozzle 62. However, in the case of ammonia monofuel combustion, pulverized fuel is not supplied, and only cold air for cooling the nozzle is supplied.

[0033] A venturi 68 and a concentrator 69 are provided within the outer cylindrical nozzle 62. The venturi 68 is provided on the inner wall of the outer cylindrical nozzle 62, extending in the circumferential direction, and reduces the flow path within the outer cylindrical nozzle 62 by bulging outward. For example, the venturi 68 includes an upstream inclined portion 68a located upstream and inclined inward, and a downstream inclined portion 68b connected to the apex of the upstream inclined portion 68a and inclined outward toward the downstream side. The venturi 68 imparts a velocity component to the flow that points toward the central axis CL.

[0034] The concentrator 69 is located downstream of the venturi 68, is fixed to the outer wall of the core air nozzle 63 and extends in the circumferential direction, and has a shape that bulges outward. For example, the concentrator 69 includes an upstream inclined portion 69a located upstream and inclined outward, a cylindrical portion 69c connected to the apex of the upstream inclined portion 68a and extending parallel to the central axis CL, and a downstream inclined portion 69b connected to the downstream end of the cylindrical portion 69c and inclined inward toward the downstream side.

[0035] The concentrator 69 expands the flow path narrowed by the venturi 68, and gives the flow a velocity component toward the outer cylindrical nozzle 62 (radial direction). Since the pulverized fuel has a larger inertial force than the primary air, it is collected on the inner wall side of the outer cylindrical nozzle 62 by the venturi 68 and the concentrator 69, forming a high concentration region of the pulverized fuel.

[0036] A second flame stabilizer 71 serving as a baffle is provided on the outer periphery of the tip of the outer cylindrical nozzle 62. The second flame stabilizer 71 is ring-shaped when the outer cylindrical nozzle 62 is viewed from the front. The second flame stabilizer 71 partially blocks the flow of secondary air flowing through the secondary air passage 73, forming a flame-stabilizing region downstream thereof. This stabilizes the flame of the pulverized fuel supplied from the outer cylindrical nozzle 62.

[0037] The secondary air flow path 73 is provided so as to cover the outer cylindrical nozzle 62. A tertiary air flow path 74 is provided on the outer circumferential side of the secondary air flow path 73 so as to cover the secondary air flow path 73. A swirler 74a that imparts a swirl to the tertiary air is provided within the tertiary air flow path 74.

[0038] Next, the operation of the burner 21 having the above configuration will be described. <When using pulverized fuel exclusively> When the pulverized fuel is exclusively fired, the supply of liquid ammonia from the liquid ammonia supply source 50 (see FIG. 1 ) is stopped, and then oil fuel is injected into the furnace 11 from the fuel injection tip 65 of the inner cylindrical nozzle 61 to start the burner 21. The oil fuel passes through the oil fuel passage 65b of the fuel injection tip 65 of the inner cylindrical nozzle 61, is atomized by gas such as steam guided from the second branch passage 65a2 of the gas passage 65a, and is injected into the furnace 11. The injected oil fuel forms a flame together with combustion air guided from the core air nozzle 63. The flame of the oil fuel is stabilized by the first flame stabilizer 67. Then, when the temperature inside the furnace 11 rises to a predetermined temperature and startup is completed, the supply of oil fuel is stopped. When the supply of oil fuel is stopped, a small amount of gas flows from the fuel injection tip 65 to cool the fuel injection tip 65. At this time, no liquid ammonia fuel is supplied to the fuel injection tip 65.

[0039] After a predetermined time has elapsed since the burner was started, pulverized fuel and primary air are gradually supplied from the outer nozzle 62, and a flame using the pulverized fuel is formed. After the burner is started, only a flame using the pulverized fuel is formed in the furnace 11, and the pulverized fuel is burned exclusively. The flame using the pulverized fuel is stabilized by the second flame stabilizer 71, and combustion is carried out in stages using secondary air supplied from the secondary air passage 73 and tertiary air supplied from the tertiary air passage 74.

[0040] <Liquid ammonia fuel combustion> When liquid ammonia fuel is exclusively burned, the operation of the mill 31 is stopped to stop the supply of pulverized fuel. However, an appropriate amount of primary air is supplied through the outer cylindrical nozzle 62. Then, to start the burner 21, oil fuel is injected into the furnace 11 from the fuel injection tip 65 of the inner cylindrical nozzle 61. The oil fuel passes through the oil fuel flow path 65b of the fuel injection tip 65 of the inner cylindrical nozzle 61, is atomized by gas such as steam guided from the second branch flow path 65a2 of the gas flow path 65a, and is injected into the furnace 11. The injected oil fuel forms a flame together with combustion air guided from the core air nozzle 63. The flame of the oil fuel is stabilized by the first flame stabilizer 67. Then, when the temperature inside the furnace 11 rises to a predetermined temperature and startup is completed, the supply of oil fuel is stopped. When the supply of oil fuel is stopped, a small amount of gas flows from the fuel injection tip 65 to cool the fuel injection tip 65.

[0041] After a predetermined time has elapsed since the start of burner startup, liquid ammonia is gradually supplied from the liquid ammonia supply source 50 to the fuel injection tip 65 of the inner cylindrical nozzle 61, and a flame of liquid ammonia fuel is formed together with combustion air supplied from the core air nozzle 63. After the burner startup, only a flame of liquid ammonia fuel is formed in the furnace 11, and the liquid ammonia fuel is burned exclusively. The flame of liquid ammonia fuel is stabilized by the first flame stabilizer 67, and combustion is carried out in stages by the primary air supplied from the outer cylindrical nozzle 62, the secondary air supplied from the secondary air passage 73, and the tertiary air supplied from the tertiary air passage 74.

[0042] The above-described embodiment has the following advantages. A fuel injection tip 65 is provided on the inner cylinder nozzle 61, so that liquid ammonia fuel and oil fuel can be injected separately. This not only makes it possible to use oil fuel when starting the burner 21, but also makes it possible to perform exclusive combustion of liquid ammonia fuel and exclusive combustion of pulverized fuel. The fuel injection tip 65 allows the ammonia fuel to be used in a liquid state, so that the amount of heat generated necessary for the mono-fuel combustion of ammonia fuel can be ensured. When starting the burner 21, the burner 21 is started by selectively supplying oil fuel from the inner cylindrical nozzle 61. After the burner 21 has started, the supply of oil fuel is stopped. When performing mono-combustion of liquid ammonia fuel, liquid ammonia fuel is selectively supplied from the inner cylindrical nozzle 61 and primary air is supplied from the outer cylindrical nozzle 62. At this time, the flame of the liquid ammonia fuel is maintained by the first flame stabilizer 67. At this time, pulverized fuel is not supplied from the outer cylindrical nozzle 62. When performing mono-combustion of pulverized fuel, the mono-combustion of pulverized fuel is performed by the pulverized fuel and primary air supplied from the outer cylindrical nozzle 62. At this time, the flame of the pulverized fuel is maintained by the second flame stabilizer 71. At this time, liquid ammonia fuel is not supplied from the inner cylindrical nozzle 61.

[0043] By providing a core air nozzle 63 on the outer circumferential side of the inner cylinder nozzle 61, it is possible to supply combustion air to the liquid ammonia fuel or oil fuel supplied from the inner cylinder nozzle 61. Then, by providing a first flame stabilizer 67 to the core air nozzle 63, it is possible to stabilize the flame of the liquid ammonia fuel or oil fuel.

[0044] [Second embodiment] Next, a second embodiment of the present disclosure will be described with reference to FIG. This embodiment is similar to the first embodiment in that the combustion of pulverized fuel and the combustion of liquid ammonia are performed, but differs from the first embodiment in that the core air nozzle 63 and the like are omitted and swirl vanes are provided. Therefore, in the following, the same components as those in the first embodiment are denoted by the same reference numerals, and the differences from the first embodiment will be mainly described.

[0045] As shown in Fig. 3, a first swirl vane 76 and a second swirl vane 77 are provided on the outer wall of the inner cylindrical nozzle 61. A plurality of these swirl vanes 76, 77 are provided in the circumferential direction around the central axis CL. Note that the venturi 68 and concentrator 69 shown in Fig. 2A of the first embodiment are not provided between the inner cylindrical nozzle 61 and the outer cylindrical nozzle 62.

[0046] The first swirl vane 76 imparts a swirl about the central axis CL to the pulverized fuel and primary air flowing inside the outer cylindrical nozzle 62. The second swirl vane 77 is located downstream of the first swirl vane 76 in the flow direction of the primary air, and imparts a swirl in the opposite direction to that of the first swirl vane 76. The fuel injection tip 65 shown in FIG. 2B is provided inside the inner cylinder nozzle 61, as in the first embodiment.

[0047] In addition to the effects common to the first embodiment, the present embodiment has the following effects. After the first swirl vane 76 imparts a swirl about the central axis CL, the second swirl vane 77 imparts a swirl in the opposite direction. As a result, when performing mono-fuel combustion of pulverized fuel by supplying pulverized fuel and primary air to the external nozzle 62, the first swirl vane 76 guides the pulverized fuel toward the inner wall of the external nozzle 62, thereby concentrating the fuel. The second swirl vane 77 returns the swirl of the primary air that has been swirled by the first swirl vane 76, thereby optimizing the flow of the primary air. When liquid ammonia fuel is used exclusively, the second swirl vane 77 located downstream can be used as a flame stabilizer.

[0048] [Third embodiment] Next, a third embodiment of the present disclosure will be described with reference to FIGS. 4A and 4B. This embodiment is similar to the first embodiment in that the mono-combustion of pulverized fuel and the mono-combustion of liquid ammonia are performed, but differs from the first embodiment in that the core air nozzle 63 and the like are omitted and liquid ammonia fuel is injected from the outside of the outer cylindrical nozzle 62. Therefore, in the following, the same components as those in the first embodiment are denoted by the same reference numerals, and the differences from the first embodiment will be mainly described.

[0049] As shown in Fig. 4A, the inner cylinder nozzle 61 supplies only oil fuel. An oil fuel injection tip (not shown) for injecting oil fuel is provided inside the inner cylinder nozzle 61. An oil flow path is formed inside this oil fuel injection tip, and atomized oil fuel is injected into the furnace 11 from multiple injection holes. The oil fuel injection tip may be a two-fluid nozzle or may be a pressure atomizer.

[0050] A concentrator 69 is provided on the outer periphery of the inner cylindrical nozzle 61. The function of the concentrator 69 is the same as that in the first embodiment.

[0051] Liquid ammonia nozzles 80 are provided on the outer circumferential side of outer cylindrical nozzle 62 at positions corresponding to tertiary air flow path 74. A plurality of liquid ammonia nozzles 80 are provided around central axis CL, and inject liquid ammonia fuel supplied from liquid ammonia supply source 50 (see FIG. 1) into furnace 11. The tip side of each liquid ammonia nozzle 80 is inclined in the direction toward central axis CL.

[0052] A liquid ammonia injection tip 82 is provided inside the liquid ammonia nozzle 80. As shown in Fig. 4B, a liquid ammonia flow path is formed inside the liquid ammonia injection tip 82, and atomized liquid ammonia fuel is injected from a plurality of injection holes 82a toward the inside of the furnace 11. The liquid ammonia injection tip 82 injects the liquid ammonia fuel by pressure spraying.

[0053] In addition to the effects common to the first embodiment, the present embodiment has the following effects. The liquid ammonia injection tip 82 allows ammonia fuel to be used in a liquid state, so that the amount of heat generated necessary for mono-fuel combustion of ammonia fuel can be ensured. As in the first embodiment, the burner can be started by supplying oil fuel from the inner cylindrical nozzle 61. When liquid ammonia fuel is exclusively burned, liquid ammonia fuel is supplied from the liquid ammonia nozzle 80 and primary air is supplied from the outer cylindrical nozzle 62. At this time, pulverized fuel is not supplied from the outer cylindrical nozzle 62. When performing mono-combustion of pulverized fuel, the mono-combustion of pulverized fuel is performed by the pulverized fuel and primary air supplied from the outer cylindrical nozzle 62. At this time, the flame of the pulverized fuel is maintained by the flame stabilizer 71. Liquid ammonia fuel is not supplied from the liquid ammonia nozzle 80. By providing a plurality of liquid ammonia nozzles 80 and configuring the burner to inject liquid ammonia fuel from the outer periphery of the outer cylindrical nozzle 62 in a direction toward the central axis CL, it is possible to realize an ammonia mono-fuel configuration without significantly changing the structure of the pulverized fuel burner. Note that the configuration may also be such that the liquid ammonia is injected in a tangential direction to the central axis CL so that the ammonia flame is stabilized by the flame stabilizer 71.

[0054] [Fourth embodiment] Next, a fourth embodiment of the present disclosure will be described with reference to FIGS. This embodiment is similar to the third embodiment in that both pulverized fuel and liquid ammonia are exclusively combusted, but differs from the third embodiment in that a core air nozzle is provided. Therefore, in the following, the same components as those in the third embodiment are denoted by the same reference numerals, and the differences from the third embodiment will be mainly described.

[0055] The burner 21 of this embodiment is provided with a core air nozzle (air nozzle) 63 that is located on the inner circumferential side of the outer cylindrical nozzle 62 and on the outer circumferential side of the inner cylindrical nozzle 61, and that is provided so as to cover the inner cylindrical nozzle 61. Combustion air and liquid ammonia are supplied into the core air nozzle 63. The tip of the core air nozzle 63 is located upstream of the tip of the inner cylindrical nozzle 61.

[0056] A first swirl vane 76 and a second swirl vane 77 are provided on the outer periphery of the inner cylindrical nozzle 61. The first swirl vane 76 and the second swirl vane 77 are the same as those in the second embodiment (FIG. 3). Note that instead of the first swirl vane 76 and the second swirl vane 77, a concentrator (pulverized coal concentration adjuster) 69 shown in FIG. 2 may be provided. In this case, as shown in FIG. 2, a venturi 68 is provided downstream of the tip of the core air nozzle 63 and upstream of the concentrator 69.

[0057] 4A, the liquid ammonia nozzle 80 is provided parallel to the central axis CL. However, as in the third embodiment, the liquid ammonia nozzle 80 may be inclined toward the central axis CL.

[0058] <When using pulverized fuel exclusively> When pulverized coal fuel is burned exclusively, the supply of liquid ammonia from the liquid ammonia supply source 50 (see FIG. 1) is stopped. Then, as shown in FIG. 6, pulverized fuel and primary air are supplied from the outer cylindrical nozzle 62, and a flame FL1 is formed using the pulverized fuel. The flame using the pulverized fuel is stabilized by the second flame stabilizer 71. At this time, no oil is supplied into the inner cylindrical nozzle 61 (stopped), no air or liquid ammonia is supplied into the core air nozzle 63 (stopped), and no liquid ammonia is supplied to the liquid ammonia nozzle 80 (stopped).

[0059] Arrow A1 indicates the flow of peripheral air formed by the secondary air supplied from the secondary air passage 73 and the tertiary air supplied from the tertiary air passage 74. A high-temperature reduction zone is formed between this arrow A1 and the flame FL1.

[0060] <Liquid ammonia fuel combustion> When the liquid ammonia fuel is exclusively burned, the operation of the mill 31 (see FIG. 1) is stopped to stop the supply of pulverized fuel. 7, liquid ammonia is supplied from the liquid ammonia supply source 50 to the liquid ammonia nozzle 80, and a flame FL2 is formed by the liquid ammonia fuel together with combustion air supplied from the core air nozzle 63. Neither pulverized fuel nor air is supplied into the outer cylindrical nozzle 62 (stopped).

[0061] By supplying combustion air from the core air nozzle 63, the flame FL2 can be formed along the central axis CL of the burner 21 without being directed toward the outer periphery. For example, as shown in Fig. 8, if the core air nozzle 63 is not provided and the combustion air is not flowed from the central axis of the burner 21, the flame FL2 will be drawn toward the outer periphery by the flow of the outer periphery air indicated by arrow A1.

[0062] 9, liquid ammonia may be supplied in addition to combustion air from the core air nozzle 63. This can promote ignition at the outlet of the burner 21.

[0063] 10, liquid ammonia may be supplied to a core air nozzle duct 64 connected to the upstream side of the core air nozzle 63. This allows liquid ammonia to be supplied to the core air nozzle 63 as shown in FIG. A This can promote mixing of liquid ammonia and air compared to when the liquid ammonia is supplied.

[0064] In addition to the effects common to the third embodiment, the present embodiment has the following effects. When liquid ammonia is burned, combustion air is supplied from the core air nozzle 63, and the flame formed by the liquid ammonia nozzle 80 FL 2 can be formed along the central axis CL of the burner 21 without facing the outer periphery.

[0065] When liquid ammonia is exclusively burned, liquid ammonia is supplied to the core air nozzle 63, so that ignition at the outlet of the burner 21 can be promoted.

[0066] By positioning the tip of the core air nozzle 63 upstream of the tip of the inner cylindrical nozzle 61, it is possible to prevent as much as possible the space through which pulverized coal flows between the inner cylindrical nozzle 61 and the outer cylindrical nozzle 62 from becoming narrow. This makes it possible to avoid impairing the combustion performance when pulverized coal is burned exclusively.

[0067] In the above-described embodiments, the boiler of the present invention has been described as a boiler that uses solid fuel as fuel, such as coal, biomass fuel, petroleum coke (PC), petroleum residue, etc.

[0068] Furthermore, the above-described embodiments have the following advantages. In the case of a wall-fired boiler in which burners are arranged in multiple rows on the boiler wall, one on top of the other and in multiple rows on the left and right, we will use as an example a boiler in which 24 burners are arranged in three rows (H, M, L) on the front wall (F) and the rear wall (R) of the furnace, with four rows on the left and right.

[0069] In some cases, one of the six burner stages is idled, and the remaining five stages provide the boiler's rated output, with the idle stages rotated. If burners that can only burn a single type of fuel are placed in each specific stage, the fuel mix ratio for the boiler during a set operating period will naturally be fixed. This makes it difficult to adjust the mix ratio depending on the procurement and supply status of multiple fuels.

[0070] Furthermore, for example, if a burner can obtain a lower output when using ammonia fuel than when using pulverized fuel, then the output of the entire boiler will naturally also decrease when it is operated in a mixed combustion or ammonia mono-combustion mode.

[0071] Even if a burner can produce the same output, if it has poor ignition properties and flame stability, it may result in the generation of unburned fuel and an increase in NOx emissions.

[0072] The burner 21 shown in each of the above-described embodiments toTherefore, in either mode, when burning pulverized fuel or liquid ammonia, there are no problems with the ignition of the fuel or the stability of the flame, the burner output can be kept the same, and there is no generation of unburned fuel or an increase in NOx.

[0073] Therefore, when firing pulverized fuel exclusively or liquid ammonia exclusively, the operation mode can be switched independently between FH, FM, FL, RH, RM, and RL, making it possible to achieve a set fuel mix ratio during a certain operating period, allowing for flexible operation.

[0074] The burner, the boiler including the burner, and the method of operating the burner described in each of the above-described embodiments can be understood, for example, as follows.

[0075] A burner according to one embodiment of the present disclosure comprises: an inner cylindrical nozzle (61) extending along a central axis (CL) and supplying liquid ammonia fuel or oil fuel into a furnace; a first flame stabilizer (67) for stabilizing the flame of the liquid ammonia fuel or oil fuel supplied from the inner cylindrical nozzle; an outer cylindrical nozzle (62) extending along the central axis and arranged to cover the inner cylindrical nozzle and supplying pulverized fuel and / or primary air into the furnace; and a second flame stabilizer (71) for stabilizing the flame of the pulverized fuel supplied from the outer cylindrical nozzle, and the inner cylindrical nozzle comprises a fuel injection tip (65) formed with an ammonia flow path through which the liquid ammonia fuel flows and an oil flow path through which the oil fuel flows, the oil flow path being a system separate from the ammonia flow path.

[0076] The inner nozzle is equipped with a fuel injection tip, which allows liquid ammonia fuel and oil fuel to be injected separately. This not only allows oil fuel to be used when starting the burner, but also allows for the exclusive combustion of liquid ammonia fuel and pulverized fuel. Since the fuel injection tip allows the ammonia fuel to be used in a liquid state, it is possible to ensure the amount of heat generated necessary for mono-fuel combustion of ammonia fuel. When starting the burner, oil fuel is selectively supplied from the inner cylindrical nozzle to start the burner, and after the burner has started, the supply of oil fuel is stopped. When liquid ammonia fuel is exclusively burned, liquid ammonia fuel is selectively supplied from the inner nozzle and primary air is supplied from the outer nozzle. At this time, the flame of the liquid ammonia fuel is maintained by the first flame stabilizer. At this time, pulverized fuel is not supplied from the outer nozzle. When pulverized fuel is exclusively combusted, the pulverized fuel and primary air are supplied from the outer nozzle. At this time, the second flame stabilizer maintains the flame of the pulverized fuel. At this time, liquid ammonia fuel is not supplied from the inner nozzle.

[0077] A burner according to one embodiment of the present disclosure includes an air nozzle (63) that is located on the inner periphery of the outer cylindrical nozzle and on the outer periphery of the inner cylindrical nozzle, and that is arranged to cover the inner cylindrical nozzle and supply combustion air, and the first flame stabilizer is provided on the air nozzle.

[0078] By providing an air nozzle on the outer periphery of the inner cylindrical nozzle, combustion air can be supplied to the liquid ammonia fuel or oil fuel supplied from the inner cylindrical nozzle. In addition, by providing a first flame stabilizer on the air nozzle, the flame of the liquid ammonia fuel or oil fuel can be stabilized.

[0079] A burner according to one embodiment of the present disclosure includes a first swirl vane (76) provided on the outer periphery of the inner cylindrical nozzle and imparting swirl around the central axis, and a second swirl vane (77) provided on the outer periphery of the inner cylindrical nozzle, located downstream of the first swirl vane in the flow direction of the primary air, and imparting swirl in the opposite direction to the first swirl vane.

[0080] After the first swirl vane imparts swirl around the central axis, the second swirl vane imparts swirl in the opposite direction. As a result, when pulverized fuel and primary air are supplied to the external nozzle, the first swirl vane guides the pulverized fuel toward the inner wall of the external nozzle, resulting in fuel enrichment. The second swirl vane returns the swirl of the primary air imparted with a swirl by the first swirl vane, thereby optimizing the flow of primary air. When liquid ammonia fuel is used exclusively, the second swirl vane located downstream can be used as the first flame stabilizer.

[0081] A burner according to one embodiment of the present disclosure comprises an inner cylindrical nozzle extending along a central axis and supplying oil fuel into a furnace, an outer cylindrical nozzle extending along the central axis and arranged to cover the inner cylindrical nozzle and supplying pulverized fuel and / or primary air into the furnace, a flame stabilizer that stabilizes the flame of the pulverized fuel supplied from the outer cylindrical nozzle, and a liquid ammonia nozzle (80) that supplies liquid ammonia fuel into the furnace, and the liquid ammonia nozzle comprises a liquid ammonia injection tip (82) that injects the liquid ammonia fuel.

[0082] The liquid ammonia injection tip allows ammonia fuel to be used in a liquid state, ensuring the calorific value required for mono-fuel combustion of ammonia fuel. The liquid ammonia injection tip enables pressure atomization of liquid ammonia fuel. The burner can be started by supplying oil fuel through the inner cylindrical nozzle. After the burner is started, the supply of oil fuel is stopped. When liquid ammonia fuel is exclusively burned, liquid ammonia fuel is supplied from the liquid ammonia nozzle and primary air is supplied from the outer cylindrical nozzle, but pulverized fuel is not supplied from the outer cylindrical nozzle. When pulverized fuel is exclusively combusted, the pulverized fuel and primary air are supplied from the outer nozzle. At this time, the flame of the pulverized fuel is maintained by a flame stabilizer. Liquid ammonia fuel is not supplied from the liquid ammonia nozzle.

[0083] In the burner according to one aspect of the present disclosure, a plurality of the liquid ammonia nozzles are provided, and each of the liquid ammonia nozzles injects the liquid ammonia fuel in a direction from an outer periphery of the outer cylindrical nozzle toward the central axis.

[0084] By providing multiple liquid ammonia nozzles and injecting liquid ammonia fuel from the outer periphery of the outer cylindrical nozzle in a direction toward the central axis, it is possible to realize an ammonia mono-fuel configuration without significantly modifying the structure of the pulverized fuel burner. Note that it is also possible to inject liquid ammonia in a tangential direction to the central axis so that the ammonia flame is stabilized by a flame stabilizer.

[0085] A burner according to one aspect of the present disclosure is provided with an air nozzle that is located on the inner periphery of the outer cylindrical nozzle and on the outer periphery of the inner cylindrical nozzle, and that is arranged to cover the inner cylindrical nozzle and supply combustion air.

[0086] By supplying combustion air from the air nozzle, the flame formed by the liquid ammonia nozzle can be formed along the central axis of the burner without being directed toward the outer periphery.

[0087] In the burner according to one aspect of the present disclosure, liquid ammonia is supplied to the air nozzle.

[0088] Supplying liquid ammonia to the air nozzle can promote ignition at the outlet of the burner.

[0089] In a burner according to one aspect of the present disclosure, the tip of the air nozzle is located upstream of the tip of the inner cylindrical nozzle.

[0090] By positioning the tip of the air nozzle upstream of the tip of the inner cylindrical nozzle, it is possible to prevent the space through which pulverized coal flows between the inner cylindrical nozzle and the outer cylindrical nozzle from becoming narrow as much as possible, thereby avoiding a loss of combustion performance when pulverized coal is burned exclusively.

[0091] In a burner according to one aspect of the present disclosure, a swirl vane, and / or a venturi, and / or a pulverized coal concentration regulator is provided on the outer periphery of the inner cylindrical nozzle between the tip of the inner cylindrical nozzle and the tip of the air nozzle.

[0092] The burner can be made compact by providing a swirl vane, a venturi, and / or a pulverized coal concentrator (PCC) on the outer periphery of the inner cylindrical nozzle, between the tip of the inner cylindrical nozzle and the tip of the air nozzle.

[0093] A burner according to one aspect of the present disclosure includes an air nozzle duct connected to the upstream side of the air nozzle and supplying combustion air to the air nozzle, Liquid ammonia is supplied to the air nozzle duct.

[0094] Supplying liquid ammonia to the air nozzle duct can promote ignition at the outlet of the burner. Also, supplying liquid ammonia to the air nozzle duct can promote mixing of the liquid ammonia and air compared to supplying liquid ammonia to the air nozzle.

[0095] A boiler according to one aspect of the present disclosure includes any one of the burners described above.

[0096] A method for operating a burner according to one aspect of the present disclosure includes an inner cylindrical nozzle extending along a central axis and supplying liquid ammonia fuel or oil fuel into a furnace, a first flame stabilizer for stabilizing a flame of the liquid ammonia fuel or oil fuel supplied from the inner cylindrical nozzle, an outer cylindrical nozzle extending along the central axis and provided so as to cover the inner cylindrical nozzle and supplying pulverized fuel and / or primary air into the furnace, and a second flame stabilizer for stabilizing the flame of the pulverized fuel supplied from the outer cylindrical nozzle, wherein the inner cylindrical nozzle has an ammonia flow path through which the liquid ammonia fuel flows and an ammonia flow path separate from the ammonia flow path. The method for operating a burner is provided with a fuel injection tip having an oil flow path formed therein through which the oil fuel flows, the method comprising: a start-up step of starting the burner by supplying oil fuel to the oil flow path of the fuel injection tip; an ammonia mono-combustion step of performing ammonia mono-combustion by supplying liquid ammonia fuel to the ammonia flow path of the fuel injection tip without supplying the pulverized fuel to the outer cylindrical nozzle; and a pulverized fuel mono-combustion step of performing pulverized fuel mono-combustion by supplying the pulverized fuel and the primary air to the outer cylindrical nozzle without supplying liquid ammonia fuel to the ammonia flow path of the fuel injection tip.

[0097] A method for operating a burner according to one aspect of the present disclosure is a method for operating a burner comprising: an inner cylindrical nozzle extending along a central axis and supplying oil fuel into a furnace; an outer cylindrical nozzle extending along the central axis and arranged to cover the inner cylindrical nozzle and supplying pulverized fuel and / or primary air into the furnace; a flame stabilizer that stabilizes the flame of the pulverized fuel supplied from the outer cylindrical nozzle; and a liquid ammonia nozzle that supplies liquid ammonia fuel into the furnace, wherein the liquid ammonia nozzle is equipped with a liquid ammonia injection tip that injects the liquid ammonia fuel. The method includes a start-up step of supplying oil fuel to the inner cylindrical nozzle to start the burner; an ammonia mono-combustion step of supplying liquid ammonia fuel to the liquid ammonia injection tip of the liquid ammonia nozzle without supplying the pulverized fuel to the outer cylindrical nozzle to perform ammonia mono-combustion; and a pulverized fuel mono-combustion step of supplying the pulverized fuel and the primary air to the outer cylindrical nozzle without supplying liquid ammonia fuel to the liquid ammonia injection tip to perform pulverized fuel mono-combustion. [Explanation of symbols]

[0098] 10. Boiler 11 Furnace 12 Combustion gas passage 13 Flue 20 Combustion equipment 21 Burner 22 Fine fuel supply pipe 23 Air register 24 Air duct 25 Additional air port 26 Additional air duct 31 Mill (Grinder) 32 Forced draft fan (FDF) 41 Gas duct 42 Air preheater 43 Denitration equipment 44 Dust collection device 45 Induced Draft Fan (IDF) 46 Desulfurization equipment 47 Chimney 50 Liquid Ammonia Source 61 Inner cylinder nozzle 62 External nozzle 63 Core air nozzle (air nozzle) 64 Core air nozzle duct (air nozzle duct) 65 fuel injection tip 65a Gas flow path 65a1 First branch flow path 65a2 Second branch flow path 65b Oil fuel passage 65c Liquid ammonia fuel flow path 67 1st flame holder 68 Venturi 68a Upstream slope 68b Downstream slope 69 Concentrator 69a Upstream slope 69b Downstream slope 69c Cylindrical part 71 Second flame holder (flame holder) 73 Secondary air flow path 74 Tertiary air flow path 74a Swivel 76 First swirl blade 77 Second swirl blade 80 Liquid Ammonia Nozzle 82 Liquid Ammonia Injection Tip 82a injection hole 101 Furnace wall 102 Superheater 103 Reheater 104 Economizer

Claims

1. an inner cylindrical nozzle extending along a central axis and supplying oil fuel into the furnace; an outer nozzle extending along the central axis and covering the inner nozzle, the outer nozzle supplying pulverized fuel and / or primary air into the furnace; a flame stabilizer that stabilizes the flame of the pulverized fuel supplied from the outer cylindrical nozzle; a liquid ammonia nozzle that supplies liquid ammonia fuel into the furnace; Equipped with the liquid ammonia nozzle includes a liquid ammonia injection tip that injects the liquid ammonia fuel, an air nozzle that is located on the inner peripheral side of the outer cylindrical nozzle and on the outer peripheral side of the inner cylindrical nozzle, and that is provided so as to cover the inner cylindrical nozzle, and that supplies combustion air; A burner in which liquid ammonia is supplied to the air nozzle.

2. a plurality of the liquid ammonia nozzles are provided, 2. The burner according to claim 1, wherein each of the liquid ammonia nozzles injects the liquid ammonia fuel in a direction from an outer periphery of the outer cylindrical nozzle toward the central axis.

3. 2. The burner according to claim 1, wherein the tip of the air nozzle is located upstream of the tip of the inner cylindrical nozzle.

4. The burner according to claim 3, wherein a swirl vane, a venturi, and / or a pulverized coal concentration regulator is provided on the outer periphery of the inner cylindrical nozzle between the tip of the inner cylindrical nozzle and the tip of the air nozzle.

5. an air nozzle duct connected to the upstream side of the air nozzle and supplying combustion air to the air nozzle; 2. The burner of claim 1, wherein liquid ammonia is supplied to said air nozzle duct.

6. A boiler equipped with the burner according to any one of claims 1 to 5.

7. an inner cylindrical nozzle extending along a central axis and supplying oil fuel into the furnace; an outer nozzle extending along the central axis and covering the inner nozzle, the outer nozzle supplying pulverized fuel and / or primary air into the furnace; a flame stabilizer that stabilizes the flame of the pulverized fuel supplied from the outer cylindrical nozzle; a liquid ammonia nozzle that supplies liquid ammonia fuel into the furnace; Equipped with The liquid ammonia nozzle is provided with a liquid ammonia injection tip that injects the liquid ammonia fuel, a starting step of supplying oil fuel to the inner cylindrical nozzle to start the burner; an ammonia combustion process in which the liquid ammonia fuel is supplied to the liquid ammonia injection tip of the liquid ammonia nozzle without supplying the pulverized fuel to the outer cylindrical nozzle, thereby performing ammonia combustion; a pulverized fuel combustion step of performing pulverized fuel combustion by supplying the pulverized fuel and the primary air to the outer cylindrical nozzle without supplying the liquid ammonia fuel to the liquid ammonia injection tip; and an air nozzle that is located on the inner peripheral side of the outer cylindrical nozzle and on the outer peripheral side of the inner cylindrical nozzle, and that is provided so as to cover the inner cylindrical nozzle, and that supplies combustion air; A method for operating a burner in which liquid ammonia is supplied to the air nozzle.

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