JP7767458B2 - Burner, boiler equipped with same, and burner operating method - Google Patents

Description

The present disclosure relates to a burner that burns, for example, pulverized solid fuel and ammonia fuel, a boiler equipped with the burner, and a method for operating the burner.

Large boilers, such as power generation boilers, have a hollow, vertically installed furnace with multiple burners mounted on the furnace wall. Large boilers also have a flue connected vertically above the furnace, with a heat exchanger installed in this flue to generate steam. The burner then injects a mixture of fuel and air (oxidizing gas) into the furnace, creating a flame, generating combustion gases that flow down the flue. A heat exchanger is installed in the area through which the combustion gases flow, and superheated steam is generated by heating the water and steam flowing through the heat transfer tubes that make up the heat exchanger.

Considerations are being made regarding burners used in boilers that combine pulverized coal and ammonia fuel, or that exclusively burn pulverized coal or ammonia fuel (see, for example, Patent Document 1).

Japanese Patent Application Laid-Open No. 2020-41748

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

This disclosure has been made in light of these circumstances, and aims to provide a burner that is capable of exclusively firing pulverized fuel and ammonia fuel, as well as a boiler equipped with such a burner and a method for operating the burner.

A burner according to one aspect 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 covering the inner cylindrical nozzle that supplies 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 is equipped with a fuel injection tip that is formed with an ammonia flow path through which the liquid ammonia fuel flows and an oil flow path through which the oil fuel flows, which is separate from the ammonia flow path.

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 covering 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 having a liquid ammonia injection tip that injects the liquid ammonia fuel.

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 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, 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.

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 oil fuel into a furnace; an outer cylindrical nozzle extending along the central axis and covering 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 having a liquid ammonia injection tip that injects the liquid ammonia fuel. The method includes a startup 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 to perform pulverized fuel mono-combustion without supplying liquid ammonia fuel to the liquid ammonia injection tip.

The burner disclosed herein makes it possible to exclusively burn pulverized fuel and ammonia fuel.

1 is a schematic configuration diagram showing a boiler according to a first embodiment of the present disclosure. FIG. FIG. 2 is a vertical cross-sectional view showing the burner of FIG. 1; FIG. 2B is a longitudinal cross-sectional view of a fuel injection tip used in the burner of FIG. 2A. FIG. 4 is a longitudinal cross-sectional view showing a burner according to a second embodiment of the present disclosure. FIG. 10 is a longitudinal cross-sectional view showing a burner according to a third embodiment of the present disclosure. FIG. 4B is a longitudinal cross-sectional view of a fuel injection tip used in the burner of FIG. 4A. FIG. 10 is a longitudinal cross-sectional view showing a burner according to a fourth embodiment of the present disclosure. FIG. 6 is a vertical cross-sectional view showing the burner shown in FIG. 5 when pulverized coal is burned exclusively. FIG. 6 is a vertical cross-sectional view showing the burner shown in FIG. 5 when liquid ammonia is burned exclusively. FIG. 10 is a vertical cross-sectional view showing a burner of a comparative example. 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. FIG. 8 is a vertical cross-sectional view of the burner showing another modified example of the burner shown in FIG. 7 when burning liquid ammonia exclusively.

One 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, but the vertical direction is not precise and may include errors.

[First embodiment]
FIG. 1 shows a boiler 10 of this embodiment that uses pulverized fuel and/or ammonia (NH ₃ ) as its main fuel.
The boiler 10 of this embodiment is a boiler that can generate superheated steam by burning pulverized fuel made from pulverized solid fuel and liquid ammonia fuel using a burner and exchanging the heat generated by this combustion with feedwater or steam. Biomass fuel, coal, etc. are used as solid fuel.

The boiler 10 has a furnace 11, a combustion device 20, and a combustion gas passage 12. The furnace 11 is a hollow rectangular cylinder installed vertically. The furnace wall 101, which forms the inner wall surface of the furnace 11, is composed of multiple heat transfer tubes and fins connecting the heat transfer tubes. The heat generated by the combustion of pulverized fuel is recovered by heat exchange with water and steam circulating inside the heat transfer tubes, while also suppressing the temperature rise of the furnace wall 101.

The combustion device 20 is installed in the lower region of the furnace 11. In this embodiment, the combustion device 20 has multiple burners 21A, 21B, 21C, 21D, 21E, and 21F (hereinafter, when these burners are not distinguished, they will be simply referred to as "burners 21") attached to the furnace wall 101. The burners 21 are arranged in multiple vertical rows at equal intervals along the furnace wall 101 in the furnace width direction (for example, arranged in the furnace width direction so as to face each of the opposing furnace walls 101 for opposed combustion). The shape of the furnace, the number of burner rows, the number of burners per row, the arrangement of the burners, etc. are not limited to this embodiment.

Burners 21A, 21B, 21C, 21D, 21E, and 21F are connected to multiple mills (pulverizers) 31A, 31B, 31C, 31D, 31E, and 31F (hereinafter, simply referred to as "mills 31") via multiple pulverized fuel supply pipes 22A, 22B, 22C, 22D, 22E, and 22F (hereinafter, simply referred to as "pulverized fuel supply pipes 22" when not distinguishing between them). Mill 31 is, for example, a vertical roller mill configured with a rotatable grinding table (not shown) supported internally and multiple grinding rollers (not shown) supported above the grinding table for rotation in conjunction with the grinding table's rotation. The solid fuel pulverized by the cooperation of the grinding rollers and 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.

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 this air register 23. The other end of the air duct 24 is connected to a forced draft fan (FDF) 32. The air supplied from the forced draft fan 32 is heated by an air preheater 42 installed in the air duct 24 and supplied to the burner 21 via the air register 23 as secondary air (combustion air, oxidizing gas) and introduced into the furnace 11.

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 these superheaters are not distinguished, they will be simply referred to as "superheaters 102"), reheaters 103A and 103B (hereinafter, when these reheaters are not distinguished, they will be simply referred to as "reheaters 103"), and a coal economizer 104 as heat exchangers for recovering heat from the combustion gas. Heat is exchanged between the combustion gas generated in the furnace 11 and the feedwater or steam circulating inside each heat exchanger. The arrangement and shape of each heat exchanger are not limited to those shown in Figure 1.

Connected 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 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. This heats 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.

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, that 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 devices such as a dust collector 44, such as an electrostatic precipitator, that removes ash and the like from the combustion gas, a desulfurization device 46 that removes sulfur oxides, and an induced draft fan (IDF) 45 that guides 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 in the environmental device is discharged to the outside of the system as exhaust gas.

When the boiler 10 is burning pulverized fuel exclusively (or co-firing with ammonia fuel), the multiple mills 31 are driven, and pulverized and classified pulverized fuel is supplied to the burner 21 along 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.

In addition, above the installation position of the burners 21 in the furnace 11, multiple additional air ports (AA ports) 25 are provided for supplying additional air for combustion (AA) into the furnace 11. The ends of additional air ducts (AA ducts) 26 branching 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 via the additional air ducts 26 as additional air for combustion.

In region A (corresponding to the height of the wind box 23) within the furnace 11 shown in FIG. 1, a flame is formed by the 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 (the total amount of primary air and secondary air) supplied to the burner 21 is set to be less than the theoretical air amount relative to the amount of fuel supplied to the burner 21. This creates a reducing atmosphere in regions A and B (the region between the top of the burner 21 and the bottom of the additional air port 25) within the furnace 11, and nitrogen oxides (NOx) generated by combustion are reduced within the furnace 11. Subsequently, in region C (the 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 from 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.

The combustion gas that flows into the combustion gas passage 12 exchanges heat 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, where nitrogen oxides are removed in the denitration device 43, and the gas exchanges heat with primary and secondary air in the air preheater 42. The gas is then discharged into the gas duct 41, where ash and other particles are removed in the dust collector 44, and sulfur oxides are removed in the desulfurization device 46 before being discharged outside the system through the chimney 47. The arrangement of the heat exchangers in the combustion gas passage 12 and the devices from the flue 13 to the gas duct 41 does not necessarily have to be in the order described above relative to the combustion gas flow.

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

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 a computer-readable storage medium. A series of processes for realizing various functions is stored in a storage medium, for example, 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.

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, and 63 has a common central axis CL, has a circular cross section, for example, and is made of metal.

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 Figure 1. The oil fuel is supplied from an oil fuel supply source (not shown) and is used when the burner 21 is started.

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 has a gas flow path 65a formed 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 of the liquid ammonia fuel flow path 65c 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 is capable of selectively injecting liquid ammonia fuel and oil fuel.

As shown in Figure 2A, a first flame stabilizer 67 is provided on the outer periphery of the tip of the inner cylindrical nozzle 61, between it and the core air nozzle 63. The first flame stabilizer 67 is, for example, vane-shaped, and imparts a swirl to the core air (central air) serving as combustion air flowing through the core air nozzle 63 around the central axis CL. The first flame stabilizer 67 stabilizes the flame of the liquid ammonia fuel injected from the inner cylindrical nozzle 61.

Pulverized fuel and primary air guided from the mill 31 (see Figure 1) are supplied into the outer cylindrical nozzle 62. However, in the case of ammonia monofuel combustion, no pulverized fuel is supplied, and only cold air is supplied to cool the nozzle.

A venturi 68 and a concentrator 69 are provided within the outer cylindrical nozzle 62. The venturi 68 extends circumferentially on the inner wall of the outer cylindrical nozzle 62 and reduces the flow path within the outer cylindrical nozzle 62 by bulging inward. For example, it has 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.

The concentrator 69 is located downstream of the venturi 68, is fixed to the outer wall of the core air nozzle 63, and extends circumferentially, bulging outward. For example, it 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.

The concentrator 69 expands the flow path narrowed by the venturi 68, imparting a velocity component to the flow toward the outer nozzle 62 (radial direction). Because pulverized fuel has a greater inertial force than primary air, it is collected by the venturi 68 and concentrator 69 on the inner wall side of the outer nozzle 62, forming a high-concentration region of pulverized fuel.

A second flame stabilizer 71, acting as a baffle, is provided at the tip and outer periphery 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 through the secondary air flow passage 73, forming a flame-stabilizing region downstream of it. This stabilizes the flame of the pulverized fuel supplied from the outer cylindrical nozzle 62.

The secondary air flow path 73 is arranged to cover the outer cylindrical nozzle 62. A tertiary air flow path 74 is arranged on the outer periphery of the secondary air flow path 73 to cover the secondary air flow path 73. A swirler 74a is provided within the tertiary air flow path 74 to impart a swirl to the tertiary air.

Next, the operation of the burner 21 having the above configuration will be described.
<When using pulverized fuel exclusively>
When performing mono-combustion of pulverized fuel, 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 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 then 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 produced by 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.

After a predetermined time has elapsed since starting the burner, 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 flow path 73 and tertiary air supplied from the tertiary air flow path 74.

<When using liquid ammonia fuel exclusively>
When the 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 produced by the oil fuel is stabilized by the first flame stabilizer 67. Then, when the temperature inside the furnace 11 has risen 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.

After a predetermined time has elapsed since the burner was started, 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 is formed using liquid ammonia fuel together with combustion air supplied from the core air nozzle 63. After the burner is started, only a flame using liquid ammonia fuel is formed in the furnace 11, and the liquid ammonia fuel is burned exclusively. The flame using liquid ammonia fuel is stabilized by the first flame stabilizer 67, and combustion is carried out in stages using primary air supplied from the outer cylindrical nozzle 62, secondary air supplied from the secondary air passage 73, and tertiary air supplied from the tertiary air passage 74.

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 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.

By providing a core air nozzle 63 on the outer periphery of the inner cylinder nozzle 61, combustion air can be supplied to the liquid ammonia fuel or oil fuel supplied from the inner cylinder nozzle 61. Furthermore, by providing a first flame stabilizer 67 on the core air nozzle 63, the flame of the liquid ammonia fuel or oil fuel can be stabilized.

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.

As shown in Figure 3, a first swirl vane 76 and a second swirl vane 77 are provided on the outer wall of the inner cylindrical nozzle 61. Multiple 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 Figure 2A of the first embodiment are not provided between the inner cylindrical nozzle 61 and the outer cylindrical nozzle 62.

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.
As in the first embodiment, the fuel injection tip 65 shown in FIG. 2B is provided inside the inner cylinder nozzle 61 .

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 to 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 exclusively burned, the second swirl vane 77 located downstream can be used as a flame stabilizer.

[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 pulverized fuel and the liquid ammonia are exclusively combusted, but differs from the first embodiment in that the core air nozzle 63 and the like are omitted and the 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.

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

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 in the first embodiment.

Liquid ammonia nozzles 80 are provided on the outer periphery of the outer cylindrical nozzle 62 at a position corresponding to the tertiary air flow path 74. Multiple liquid ammonia nozzles 80 are provided around the central axis CL and inject liquid ammonia fuel supplied from the liquid ammonia supply source 50 (see Figure 1) into the furnace 11. The tip of each liquid ammonia nozzle 80 is inclined toward the central axis CL.

A liquid ammonia injection tip 82 is provided within the liquid ammonia nozzle 80. As shown in FIG. 4B, a liquid ammonia flow path is formed within the liquid ammonia injection tip 82, and atomized liquid ammonia fuel is injected into the furnace 11 from multiple injection holes 82a. The liquid ammonia injection tip 82 injects the liquid ammonia fuel by pressure spraying.

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 the pulverized fuel is exclusively combusted, the pulverized fuel is combusted with 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 modifying 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.

[Fourth embodiment]
Next, a fourth embodiment of the present disclosure will be described with reference to FIGS. 5 to 10. FIG.
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, etc. 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.

The burner 21 of this embodiment is equipped with a core air nozzle (air nozzle) 63, which is located on the inner periphery of the outer cylindrical nozzle 62 and on the outer periphery of the inner cylindrical nozzle 61, and which 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.

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 (Figure 3). Note that the first swirl vane 76 and the second swirl vane 77 may be replaced with a concentrator (pulverized coal concentration regulator) 69 shown in Figure 2. In this case, as shown in Figure 2, a venturi 68 is provided downstream of the tip of the core air nozzle 63 and upstream of the concentrator 69.

Unlike the third embodiment shown in Figure 4A, the liquid ammonia nozzle 80 is arranged 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.

<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 (suspended), no air or liquid ammonia is supplied into the core air nozzle 63 (suspended), and no liquid ammonia is supplied to the liquid ammonia nozzle 80 (suspended).

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

<When using liquid ammonia fuel exclusively>
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).

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 Figure 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 peripheral air indicated by arrow A1.

As shown in Figure 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.

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 makes it possible to promote mixing of the liquid ammonia and air compared to the case in which liquid ammonia is supplied to the core air nozzle 63 as shown in FIG.

In addition to the effects common to the third embodiment, the present embodiment has the following effects.
When liquid ammonia is burned exclusively, by supplying combustion air from the core air nozzle 63, the flame FL2 formed by the liquid ammonia nozzle 80 can be formed along the central axis CL of the burner 21 without being directed toward the outer periphery.

When liquid ammonia is burned exclusively, liquid ammonia is supplied to the core air nozzle 63, which promotes ignition at the outlet of the burner 21.

By positioning the tip of the core air nozzle 63 upstream of the tip of the inner cylindrical nozzle 61, it is possible to minimize the narrowing of the space through which pulverized coal flows between the inner cylindrical nozzle 61 and the outer cylindrical nozzle 62. This prevents the combustion performance of pulverized coal from being impaired when burning only pulverized coal.

In each of the above-described embodiments, the boiler of the present invention has been described as a boiler that uses solid fuel as fuel. Examples of solid fuels used in boilers include coal, biomass fuel, petroleum coke (PC), and petroleum residue.

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 on the top and bottom (H, M, L) and four rows on the left and right on each of the front wall (F) and rear wall (R) of the furnace.

Of the six burner stages, one stage is idled and the remaining five stages provide the boiler's rated output, with the idle stages rotated. If burners capable of burning only one type of fuel were placed in each specific stage, the fuel mix ratio for the boiler during a set operating period would naturally be fixed. This makes it difficult to adjust the mix ratio depending on the procurement and supply status of multiple fuels.

Furthermore, for example, if a burner can produce lower output when using ammonia fuel than when using pulverized fuel, the output of the entire boiler will naturally also be lower when it is operated in a mixed or ammonia-only combustion mode.

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

According to the burner 21 shown in each of the above-described embodiments, in either the mode of exclusively burning pulverized fuel or the mode of exclusively burning 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.

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

The burner described in each of the above-described embodiments, the boiler equipped with the same, and the method of operating the burner can be understood, for example, as follows.

A burner according to one aspect 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) that stabilizes 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) that stabilizes the flame of the pulverized fuel supplied from the outer cylindrical nozzle, and the inner cylindrical nozzle is equipped with 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, which is separate from the ammonia flow path.

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 performing mono-combustion of liquid ammonia fuel, liquid ammonia fuel is selectively supplied from the inner cylindrical nozzle and primary air is supplied from the outer cylindrical 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 cylindrical nozzle.
When the pulverized fuel is exclusively combusted, the pulverized fuel is combusted with the pulverized fuel and primary air supplied from the outer nozzle. At this time, the flame of the pulverized fuel is maintained by the second flame stabilizer. At this time, the liquid ammonia fuel is not supplied from the inner nozzle.

In one aspect of the burner disclosed herein, an air nozzle (63) is provided that supplies combustion air and is located on the inner periphery of the outer cylindrical nozzle and on the outer periphery of the inner cylindrical nozzle, and that covers the inner cylindrical nozzle, and the first flame stabilizer is provided on the air nozzle.

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. Furthermore, by providing a first flame stabilizer on the air nozzle, the flame of the liquid ammonia fuel or oil fuel can be stabilized.

A burner according to one aspect of the present disclosure comprises 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.

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, thereby concentrating the fuel. The second swirl vane returns the swirl of the primary air that has been swirled by the first swirl vane, thereby optimizing the flow of primary air.
When liquid ammonia fuel is exclusively burned, the second swirl vane located downstream can be used as the first flame stabilizer.

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 covering 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, the liquid ammonia nozzle comprising a liquid ammonia injection tip (82) that injects the liquid ammonia fuel.

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.

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

By providing multiple liquid ammonia nozzles and injecting liquid ammonia fuel from the outer periphery of the outer nozzle toward the central axis, a mono-ammonia combustion configuration can be achieved without significantly modifying the structure of the pulverized fuel burner. It is also possible to inject liquid ammonia in a tangential direction relative to the central axis so that the ammonia flame is stabilized using a flame stabilizer.

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 covers the inner cylindrical nozzle and supplies combustion air.

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 rather than directed toward the outer periphery.

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

Supplying liquid ammonia to the air nozzle can promote ignition at the burner outlet.

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.

By positioning the tip of the air nozzle upstream of the tip of the inner nozzle, it is possible to minimize the narrowing of the space between the inner and outer nozzles through which pulverized coal flows. This prevents a loss of combustion performance when firing pulverized coal exclusively.

In a burner according to one aspect of the present disclosure, 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.

The burner can be made compact by providing swirl vanes, 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.

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.

By supplying liquid ammonia to the air nozzle duct, ignition at the burner outlet can be promoted. Furthermore, by supplying liquid ammonia to the air nozzle duct, mixing of the liquid ammonia and air can be promoted compared to when liquid ammonia is supplied to the air nozzle.

A boiler according to one aspect of the present disclosure is equipped with any of the burners described above.

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 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, 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.

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 oil fuel into a furnace; an outer cylindrical nozzle extending along the central axis and covering 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 having a liquid ammonia injection tip that injects the liquid ammonia fuel. The method includes a startup 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 to perform pulverized fuel mono-combustion without supplying liquid ammonia fuel to the liquid ammonia injection tip.

10 Boiler 11 Furnace 12 Combustion gas passage 13 Flue 20 Combustion device 21 Burner 22 Pulverized fuel supply pipe 23 Air register
24 Air duct
25 Additional air port 26 Additional air duct 31 Mill (crusher)
32 Forced draft fan (FDF)
41 Gas duct 42 Air preheater 43 Denitrification device 44 Dust collector 45 Induced draft fan (IDF)
46 Desulfurization device 47 Chimney 50 Liquid ammonia supply source 61 Inner cylinder nozzle 62 Outer cylinder 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 flow path 65c Liquid ammonia fuel flow path 67 First flame holder 68 Venturi 68a Upstream inclined portion 68b Downstream inclined portion 69 Concentrator 69a Upstream inclined portion 69b Downstream inclined portion 69c Cylindrical portion 71 Second flame holder (flame holder)
73 Secondary air flow path 74 Tertiary air flow path 74a Swirler 76 First swirl vane 77 Second swirl vane 80 Liquid ammonia nozzle 82 Liquid ammonia injection tip 82a Injection hole 101 Furnace wall 102 Superheater 103 Reheater 104 Economizer

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