TWI850917B - Burner, boiler equipped with the same, and burner operation method - Google Patents

Abstract

A burner capable of performing dedicated combustion of fine powder fuel and dedicated combustion of ammonia fuel is provided. The burner comprises: an inner cylinder nozzle (61) extending along a central axis (CL) and supplying liquid ammonia fuel or oil fuel into a furnace; a first flame retainer (67) for retaining the flame of the liquid ammonia fuel or oil fuel supplied from the inner cylinder nozzle (61); an outer cylinder nozzle (62) extending along the central axis (CL) and arranged to cover the inner cylinder nozzle (61). ) for supplying powdered fuel and/or primary air into the furnace (11); and a second flame retainer (71) for maintaining the flame of the powdered fuel supplied from the outer tube nozzle (62), the inner tube nozzle (61) having a fuel injection nozzle, the fuel injection nozzle forming an ammonia flow path for the flow of liquid ammonia fuel and an oil flow path for the flow of oil fuel of a system different from the ammonia flow path.

Description

Burner, boiler equipped with the same, and burner operation method

The present invention, for example, relates to a burner, a boiler equipped with the same, and an operating method of the burner, which burns a fine powder fuel obtained by pulverizing a solid fuel and an ammonia fuel.

Large boilers such as power generation boilers have a hollow furnace that is set in the lead vertical direction, and a plurality of burners are arranged on the wall surface of the furnace. In addition, a large boiler is connected to a flue above the lead vertical direction of the furnace, and a heat exchanger for generating steam is arranged in the flue. Then, the burner sprays a mixed gas of fuel and air (oxidizing gas) into the furnace to form a flame, and the generated combustion gas flows into the flue. The heat exchanger is set in the area where the combustion gas flows, and the water or steam flowing in the heat transfer tube constituting the heat exchanger is heated to generate superheated steam.

As a burner used in a boiler, there are studies on the method of burning a mixture of pulverized coal and ammonia fuel, or the method of burning pulverized coal exclusively and ammonia fuel exclusively (for example, Patent Document 1). [Prior Art Document] [Patent Document]

[Patent Document 1] Japanese Patent Application Publication No. 2020-41748

[The problem the invention is trying to solve]

However, in Patent Document 1, the ammonia fuel is based on the premise of being supplied as a gas, and there is no examination of using it as a liquid. Therefore, even if a gas is used as an ammonia fuel, sufficient calorific value cannot be ensured, and it is not practical for ammonia-only combustion. Even if liquid ammonia fuel is applied to Patent Document 1, there is a problem that the flame temperature decreases due to the heat of vaporization, resulting in a decrease in flame protection performance.

The present invention was completed in view of the above situation, and its purpose is to provide a burner that can perform dedicated combustion of micro-powder fuel and dedicated combustion of ammonia fuel respectively, and a boiler equipped with the same and a method for operating the burner. [Technical means for solving the problem]

A burner in one aspect of the present invention comprises: an inner cylinder nozzle extending along the central axis and supplying liquid ammonia fuel or oil fuel into a furnace; a first flame retainer, which retains the flame of the liquid ammonia fuel or oil fuel supplied from the inner cylinder nozzle; an outer cylinder nozzle extending along the central axis and arranged to cover the inner cylinder nozzle and supplying powdered fuel and/or primary air into the furnace; and a second flame retainer, which retains the flame of the powdered fuel supplied from the outer cylinder nozzle, the inner cylinder nozzle comprising a fuel injection nozzle, the fuel injection nozzle forming an ammonia flow path for the liquid ammonia fuel to flow and an oil flow path for the oil fuel of a system different from the ammonia flow path to flow.

A burner in one aspect of the present invention comprises: an inner cylinder nozzle extending along the central axis and supplying oil fuel into the furnace; an outer cylinder nozzle extending along the aforementioned central axis and arranged to cover the aforementioned inner cylinder nozzle and supplying micro powder fuel and/or primary air into the aforementioned furnace; a flame retainer that retains the flame of the aforementioned micro powder fuel supplied from the aforementioned outer cylinder nozzle; and a liquid ammonia nozzle that supplies liquid ammonia fuel into the aforementioned furnace, the aforementioned liquid ammonia nozzle having a liquid ammonia injection nozzle that sprays the aforementioned liquid ammonia fuel.

The operating method of a burner in one aspect of the present invention comprises: an inner cylinder nozzle extending along the central axis and supplying liquid ammonia fuel or oil fuel into a furnace; a first flame retainer, which retains the flame of the liquid ammonia fuel or oil fuel supplied from the inner cylinder nozzle; an outer cylinder nozzle extending along the central axis and arranged to cover the inner cylinder nozzle and supplying powder fuel and/or primary air into the furnace; and a second flame retainer, which retains the flame of the powder fuel supplied from the outer cylinder nozzle, the inner cylinder nozzle having a fuel injection nozzle, the fuel injection nozzle forming a nozzle for supplying the liquid ammonia fuel flow. The operating method comprises: an ammonia flow path for movement, and an oil flow path for flow of the aforementioned oil fuel in a system different from the ammonia flow path, and comprises: a starting process, which supplies the oil fuel to the aforementioned oil flow path of the aforementioned fuel injection nozzle to start the burner; an ammonia-only combustion process, which does not supply the aforementioned fine powder fuel to the aforementioned outer cylinder nozzle, but supplies liquid ammonia fuel to the aforementioned ammonia flow path of the aforementioned fuel injection nozzle to carry out ammonia-only combustion; and a fine powder fuel-only combustion process, which does not supply the liquid ammonia fuel to the aforementioned ammonia flow path of the aforementioned fuel injection nozzle, but supplies the aforementioned fine powder fuel and the aforementioned primary air to the aforementioned outer cylinder nozzle to carry out fine powder fuel-only combustion.

The operating method of a burner in one aspect of the present invention comprises: an inner cylinder nozzle extending along a central axis and supplying oil fuel into a furnace; an outer cylinder nozzle extending along the aforementioned central axis and arranged to cover the aforementioned inner cylinder nozzle and supplying fine powder fuel and/or primary air into the aforementioned furnace; a flame retainer that retains the flame of the fine powder fuel supplied from the aforementioned outer cylinder nozzle; and a liquid ammonia nozzle that supplies liquid ammonia fuel into the aforementioned furnace, the aforementioned liquid ammonia nozzle having a liquid for spraying the aforementioned liquid ammonia fuel. Ammonia injection nozzle, the operation method comprises: a starting process, which supplies oil fuel to the aforementioned inner cylinder nozzle to start the burner; an ammonia-only combustion process, which does not supply the aforementioned fine powder fuel to the aforementioned outer cylinder nozzle, but supplies liquid ammonia fuel to the aforementioned liquid ammonia nozzle to perform ammonia-only combustion; and a fine powder fuel-only combustion process, which does not supply liquid ammonia fuel to the aforementioned liquid ammonia injection nozzle, but supplies the aforementioned fine powder fuel and the aforementioned primary air to the aforementioned outer cylinder nozzle to perform fine powder fuel-only combustion. [Effect of the invention]

According to the burner of the present invention, dedicated combustion of pulverized fuel and dedicated combustion of ammonia fuel can be performed separately.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. Furthermore, the present invention is not limited to the embodiment, and when there are multiple embodiments, the invention also includes a structure combining the embodiments. In the following description, "up" or "above" indicates the upper side in the lead vertical direction, and "down" or "below" indicates the lower side in the lead vertical direction. This lead vertical direction is not strict and contains errors.

[First embodiment] FIG1 shows a boiler 10 of this embodiment that uses pulverized fuel and/or ammonia (NH ₃ ) fuel as main fuel. The boiler 10 of this embodiment burns pulverized solid fuel and liquid ammonia fuel by a burner, and the heat generated by the combustion is exchanged with feed water or steam to generate superheated steam. Biomass fuel or coal is used as solid fuel.

The boiler 10 comprises a furnace 11, a combustion device 20, and a combustion gas passage 12. The furnace 11 is in the shape of a square tube and is arranged along the lead vertical direction. The furnace wall 101 constituting the inner wall surface of the furnace 11 is composed of a plurality of heat transfer tubes and connecting tube segments connecting the heat transfer tubes to each other, and the heat generated by the combustion of the pulverized fuel is recovered by heat exchange with water or steam flowing inside the heat transfer tubes, and the temperature rise of the furnace wall 101 is suppressed.

The combustion device 20 is installed in the lower area of the furnace 11. In the present embodiment, the combustion device 20 has a plurality of burners 21A, 21B, 21C, 21D, 21E, and 21F (hereinafter referred to as "burners 21" when the burners are not distinguished) installed on the furnace wall 101. The burners 21 are arranged at equal intervals along the furnace wall 101 in the furnace circumference direction (for example, in a manner of opposing combustion, the burners are arranged to face each other in the furnace circumference direction on the opposing furnace walls 101), and are arranged in a plurality of sections along the lead 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 those in this embodiment.

The burners 21A, 21B, 21C, 21D, 21E, and 21F are connected to a plurality of grinders (crushers) 31A, 31B, 31C, 31D, 31E, and 31F (hereinafter referred to as "crushers 31" when the grinders are not distinguished) through a plurality of powder fuel supply pipes 22A, 22B, 22C, 22D, 22E, and 22F, respectively. The grinders 31 are, for example, vertical roller grinders that support a grinding platform (not shown) internally so as to be rotatable and support a plurality of grinding rollers (not shown) above the grinding platform so as to be rotatable in conjunction with the rotation of the grinding platform. The solid fuel crushed by the cooperative operation of the crushing roller and the crushing platform is transported to the classifier (not shown) provided in the grinder 31 by the primary air (transportation gas, oxidizing gas) supplied to the grinder 31. In the classifier, the fuel is classified into fine powder fuel with a particle size below that suitable for combustion in the burner 21 and agglomerate fuel with a particle size larger than the particle size. The fine powder fuel is supplied to the burner 21 through the fine powder fuel supply pipe 22 together with the primary air through the classifier. The agglomerate fuel that has not passed through the classifier falls onto the crushing platform due to its own weight inside the grinder 31 and is crushed again.

A wind box (air regulator) 23 is provided outside the furnace 11 at the installation position of the burner 21, and one end of an air duct (air passage) 24 is connected to the wind box 23. A forced draft fan (FDF: Forced Draft Fan) 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 provided in the air duct 24, and is supplied to the burner 21 as secondary air (combustion air, oxidizing gas) through the wind box 23, and then is injected into the furnace 11.

The combustion gas passage 12 is connected to the upper part of the furnace 11 in the vertical direction. In the combustion gas passage 12, as heat exchangers for recovering the heat of the combustion gas, there are provided: superheaters 102A, 102B, 102C (hereinafter referred to as "superheaters 102" when the superheaters are not distinguished), reheaters 103A, 103B (hereinafter referred to as "reheaters 103" when the reheaters are not distinguished), and economizer 104, so that heat is exchanged between the combustion gas generated in the furnace 11 and the feed water or steam flowing inside each heat exchanger. In addition, the arrangement and shape of each heat exchanger are not limited to the form described in Figure 1.

A flue 13 is connected to the downstream side of the combustion gas passage 12 to discharge the combustion gas that has been overheated in the heat exchanger. The flue 13 is provided with an air preheater (air heater) 42 between the flue 13 and the air duct 24, and heat is exchanged between the air flowing in the air duct 24 and the combustion gas flowing in the flue 13, thereby heating the primary air supplied to the grinder 31 or the secondary air supplied to the burner 21, thereby further recovering heat from the combustion gas after the heat exchange with water or steam.

Furthermore, a denitrification device 43 may be provided in the flue 13 at a position upstream of the air preheater 42. The denitrification device 43 supplies a reducing agent having the function of reducing nitrogen oxides such as ammonia and urea water to the combustion gas flowing in the flue 13, so that the reaction between nitrogen oxides (NOx) in the combustion gas supplied with the reducing agent and the reducing agent is promoted by the catalytic action of the denitrification catalyst provided in the denitrification device 43, thereby removing and reducing nitrogen oxides in the combustion gas. A gas channel 41 is connected to the flue 13 at a position downstream of the air preheater 42. In the gas passage 41, there is a dust collecting device 44 such as an electric dust collector for removing ash from the combustion gas, or an environmental device such as a desulfurization device 46 for removing sulfur oxides, or an induced draft fan (IDF: Induced Draft Fan) 45 for guiding the exhaust gas to such environmental devices. The downstream end of the gas passage 41 is connected to the chimney 47, and the combustion gas treated by the environmental device is discharged out of the system as exhaust gas.

In the case of performing dedicated combustion of the fine powder fuel (or mixed combustion with ammonia fuel) in the boiler 10, if the plurality of grinders 31 are driven, the fine powder fuel that has been crushed and classified is supplied to the burner 21 through the fine powder fuel supply pipe 22 together with the primary air. In addition, the secondary air heated by the air preheater 42 is supplied to the burner 21 from the air duct 24 through the wind box 23. The burner 21 blows the fine powder fuel mixed air formed by mixing the fine powder fuel with the primary air into the furnace 11, and blows the secondary air into the furnace 11. The fine powder fuel mixed air blown into the furnace 11 is ignited and reacts with the secondary air to form a flame. A flame is formed in the lower area of the furnace 11, and the high-temperature combustion gas rises in the furnace 11 and flows into the combustion gas passage 12. In the present embodiment, air is used as the oxidizing gas (primary air, secondary air), but a gas having a higher or lower oxygen ratio than air may be used, and the ratio of the amount of oxygen to the amount of fuel supplied is adjusted to an appropriate range, thereby achieving stable combustion in the furnace 11.

Furthermore, a plurality of additional air ports (AA ports) 25 for supplying additional air (AA: Additional Air) for combustion into the furnace 11 are provided above the installation position of the burner 21 of the furnace 11. The additional air ports 25 are connected to the ends of the additional air passages (AA passages) 26 branched from the air duct 24, and a part of the air supplied from the blower 32 is supplied to the additional air ports 25 through the additional air passages 26 as additional air for combustion.

In the region A (region 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 the combustion of the mixed air of the primary air and the pulverized fuel and the secondary air. Here, the air ratio of the region A is set to be 1 or less, specifically, the air amount (the total amount of the primary air and the secondary air) supplied to the burner 21 is set to be less than the theoretical air amount of the fuel amount supplied to the burner 21, so that the region A and the region B (the region from the uppermost part of the burner 21 to the lowermost part of the additional air port 25) inside the furnace 11 become a reducing environment, and the nitrogen oxides (NOx) generated by the combustion are reduced inside the furnace 11. Afterwards, zone C (the zone above the bottom of the additional air port 25) supplies additional air for combustion from the additional air port 25 to the combustion gas after NOx reduction to complete the combustion, but the reduction effect of zones A and B reduces the amount of NOx generated.

The combustion gas flowing into the combustion gas passage 12 exchanges heat with water or steam through the superheater 102, the reheater 103, and the economizer 104 disposed inside the combustion gas passage 12, and is then discharged to the flue 13, and nitrogen oxides are removed through the denitrification device 43, and heat is exchanged with the primary air and the secondary air through the air preheater 42, and is further discharged to the gas passage 41, and ash and the like are removed through the dust collecting device 44, and sulfur oxides are removed through the desulfurization device 46, and then discharged to the outside of the system from the chimney 47. In addition, the arrangement of the heat exchangers of the combustion gas passage 12 and the flue 13 to the gas passage 41 does not necessarily have to be arranged in the above-described order with respect to the flow of the combustion gas.

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

The switching between the micro powder fuel and the ammonia fuel can be performed manually by the operator or by the command of the 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 storage medium readable by a computer. Then, a series of processes used to realize various functions are stored in the form of a program in a storage medium, and the CPU reads the program into the RAM, etc., and performs information processing and calculation processing to realize various functions. In addition, the program can also be applied to: the form of being pre-installed in a ROM or other storage medium, the form of being provided in a state of being stored in a storage medium readable by a computer, and the form of being transmitted through wired or wireless communication means, etc. Computer-readable storage media refers to magnetic disks, magneto-optical disks, CD-ROMs, DVD-ROMs, semiconductor memories, etc.

FIG2A shows a burner 21. The burner 21 can perform both dedicated combustion of fine powder fuel and dedicated combustion of liquid ammonia fuel. The burner 21 has an inner cylinder nozzle 61 extending along the center axis CL and an outer cylinder nozzle 62 arranged to cover the inner cylinder nozzle 61. A central air nozzle 63 is provided on the outer circumference of the inner cylinder nozzle 61 and the inner circumference of the outer cylinder nozzle 62. Each nozzle 61, 62, 63 has a common center axis CL, and is circular in 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 of FIG. 1. The oil fuel is supplied from the oil fuel supply source not shown in the figure, and is used when the burner 21 is started.

A fuel injection nozzle 65 is provided inside the inner tube nozzle 61 (see FIG. 2B ). The fuel injection nozzle 65 is a dual-fluid nozzle. As shown in FIG. 2B , a gas flow path 65a is formed in the center of the fuel injection nozzle 65, a plurality of oil fuel flow paths 65b are formed on the outer peripheral side thereof, and a plurality of liquid ammonia fuel flow paths 65c are formed on the outer peripheral side thereof. In the gas flow path 65a, pressurized steam or air used to atomize the oil fuel and the liquid ammonia fuel flows. 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 gas supplied by the branch flow paths 65a1 and 65a2 is used to atomize the liquid ammonia fuel and the oil fuel and supply them to the furnace 11. On the upstream side of the oil fuel flow path 65b, an oil fuel supply source is connected, and its opening and opening are adjusted by one or more oil fuel valves not shown. The oil fuel valve can be controlled by a control unit. On the upstream side of the liquid ammonia fuel flow path 65c, a liquid ammonia supply source 50 (see FIG. 1) is connected, and its opening and opening are adjusted by one or more liquid ammonia fuel valves not shown. The liquid ammonia fuel valve can be controlled by a control unit. The fuel injection nozzle 65 of the above structure can selectively inject liquid ammonia fuel and oil fuel.

As shown in FIG. 2A , a first flame retainer 67 is provided on the outer periphery of the front end of the inner cylinder nozzle 61 between the inner cylinder nozzle 61 and the core air nozzle 63. The first flame retainer 67 is, for example, in the shape of a fan blade, and imparts rotation about a central axis CL to the core air (core air) as combustion air flowing through the core air nozzle 63. The first flame retainer 67 retains the flame of the liquid ammonia fuel ejected from the inner cylinder nozzle 61.

The outer cylinder nozzle 62 is supplied with the fine powder fuel and primary air guided from the mill 31 (see FIG1 ). However, in the case of ammonia-only combustion, the fine powder fuel is not supplied but only the cold air for cooling the nozzle is supplied.

A constriction portion 68 and a concentrator 69 are provided in the outer cylinder nozzle 62. The constriction portion 68 is provided to extend in the circumferential direction on the inner wall of the outer cylinder nozzle 62, and constricts the flow path in the outer cylinder nozzle 62 by a shape that bulges toward the inner circumference. For example, it includes an upstream side inclined portion 68a located on the upstream side and inclined toward the inner circumference, and a downstream side inclined portion 68b connected to the vertex of the upstream side inclined portion 68a and inclined toward the outer circumference toward the downstream side. The constriction portion 68 is used to impart a velocity component toward the center axis CL to the flow.

The concentrator 69 is located on the downstream side of the restricting portion 68, and is fixedly extended in the circumferential direction on the outer wall of the central air nozzle 63, and has a shape that bulges toward the outer circumference. For example, it has an upstream side inclined portion 69a located on the upstream side and inclined toward the outer circumference, a cylindrical portion 69c connected to the vertex of the upstream side inclined portion 68a and extending parallel to the central axis CL, and a downstream side inclined portion 69b connected to the downstream end of the cylindrical portion 69c and inclined toward the inner circumference toward the downstream side.

The concentrator 69 expands the flow path narrowed by the constriction 68, thereby imparting a velocity component to the flow in the direction (radius direction) toward the outer tube nozzle 62. The inertial force of the micro-powder fuel is greater than that of primary air, so it is concentrated on the inner wall side of the outer tube nozzle 62 by the constriction 68 and the concentrator 69, forming a high concentration area of micro-powder fuel.

A second flame retainer 71 serving as a baffle is provided at the front end and the outer peripheral side of the outer cylinder nozzle 62. The second flame retainer 71 is annular when the outer cylinder nozzle 62 is viewed from the front. The flow of the secondary air flowing in the secondary air flow path 73 is partially blocked by the second flame retainer 71, and a flame retaining area is formed on the downstream side thereof. In this way, the flame of the fine powder fuel supplied from the outer cylinder nozzle 62 is retained.

The secondary air flow path 73 is provided so as to cover the outer cylinder nozzle 62. A tertiary air flow path 74 is provided on the outer peripheral side of the secondary air flow path 73 so as to cover the secondary air flow path 73. In the tertiary air flow path 74, a rotator 74a for imparting rotation to the tertiary air is provided.

Next, the operation of the burner 21 of the above structure is described. <When the dedicated combustion of the fine powder fuel is performed> When the dedicated combustion of the fine powder fuel is performed, the supply of liquid ammonia from the liquid ammonia supply source 50 (see FIG. 1) is stopped, and then the burner 21 is started, and the oil fuel is sprayed from the fuel spray nozzle 65 of the inner cylinder nozzle 61 into the furnace 11. The oil fuel passes through the oil fuel flow path 65b of the fuel spray nozzle 65 of the inner cylinder nozzle 61, and is atomized by the gas such as steam guided from the second branch flow path 65a2 of the gas flow path 65a, and is sprayed into the furnace 11. The injected oil fuel forms a flame together with the combustion air guided from the central air nozzle 63. The flame caused by the oil fuel is maintained by the first flame protector 67. Then, if the temperature in the furnace 11 rises to a predetermined temperature and the startup is completed, the supply of oil fuel is stopped. If the supply of oil fuel is stopped, a small amount of gas flows from the fuel injection nozzle 65 for cooling the fuel injection nozzle 65. At this time, liquid ammonia fuel is not supplied to the fuel injection nozzle 65.

After a predetermined time has passed since the start of the burner, the powder fuel and primary air are slowly supplied from the outer cylinder nozzle 62 to form a flame caused by the powder fuel. After the burner is started, only the flame of the powder fuel is formed in the furnace 11, and the powder fuel is burned exclusively. The flame of the powder fuel is maintained by the second flame retainer 71, and is burned in stages by the secondary air supplied from the secondary air flow path 73 and the tertiary air supplied from the tertiary air flow path 74.

<When exclusively burning liquid ammonia fuel> When exclusively burning liquid ammonia fuel, the operation of the mill 31 is stopped and the supply of the pulverized fuel is stopped. However, primary air is supplied in an appropriate amount through the outer cylinder nozzle 62. Then, in order to start the burner 21, the oil fuel is sprayed into the furnace 11 from the fuel spray nozzle 65 of the inner cylinder nozzle 61. The oil fuel passes through the oil fuel flow path 65b of the fuel spray nozzle 65 of the inner cylinder nozzle 61, and is atomized by the gas such as steam guided from the second branch flow path 65a2 of the gas flow path 65a and sprayed into the furnace 11. The sprayed oil fuel forms a flame together with the combustion air guided from the central air nozzle 63. The flame caused by the oil fuel is maintained by the first flame protector 67. Then, if the temperature inside the furnace 11 rises to a predetermined temperature and the startup is completed, the supply of oil fuel is stopped. If the supply of oil fuel is stopped, a small amount of gas flows from the fuel injection nozzle 65 to cool the fuel injection nozzle 65.

After a predetermined time has passed since the start of the burner, liquid ammonia is slowly supplied from the liquid ammonia supply source 50 to the fuel injection nozzle 65 of the inner cylinder nozzle 61, and a flame caused by the liquid ammonia fuel is formed together with the combustion air supplied from the center air nozzle 63. After the burner is started, only the flame of the liquid ammonia fuel is formed in the furnace 11, and the liquid ammonia fuel is burned exclusively. The flame of the liquid ammonia fuel is maintained by the first flame retainer 67, and is burned in stages by the primary air supplied from the outer cylinder nozzle 62, the secondary air supplied from the secondary air flow path 73, and the tertiary air supplied from the tertiary air flow path 74.

The effects of the present embodiment described above are as follows. A fuel injection nozzle 65 is provided in the inner cylinder nozzle 61, and liquid ammonia fuel and oil fuel can be injected separately. In this way, not only oil fuel can be used when starting the burner 21, but also dedicated combustion of liquid ammonia fuel and dedicated combustion of fine powder fuel can be performed. Ammonia fuel can be used as a liquid by the fuel injection nozzle 65, so the calorific value required for the dedicated combustion of ammonia fuel can be ensured. When the burner 21 is started, oil fuel is selectively supplied from the inner cylinder nozzle 61 to start the burner 21. After the burner 21 is started, the supply of oil fuel is stopped. When performing dedicated combustion of liquid ammonia fuel, liquid ammonia fuel is selectively supplied from the inner cylinder nozzle 61 and primary air is supplied from the outer cylinder nozzle 62. At this time, the flame of the liquid ammonia fuel is maintained by the first flame retainer 67. At this time, the fine powder fuel is not supplied from the outer cylinder nozzle 62. When performing dedicated combustion of fine powder fuel, dedicated combustion of fine powder fuel is performed by the fine powder fuel and primary air supplied from the outer cylinder nozzle 62. At this time, the flame of the fine powder fuel is maintained by the second flame retainer 71. At this time, the liquid ammonia fuel is not supplied from the inner cylinder nozzle 61.

The central air nozzle 63 is provided on the outer peripheral side of the inner cylinder nozzle 61, thereby supplying combustion air to the liquid ammonia fuel or oil fuel supplied from the inner cylinder nozzle 61. Furthermore, by providing the first flame protector 67 in the central air nozzle 63, the flame of the liquid ammonia fuel or oil fuel can be stabilized.

[Second embodiment] Next, the second embodiment of the present invention is described using FIG3. This embodiment is the same as the first embodiment in that it performs dedicated combustion of fine powder fuel and dedicated combustion of liquid ammonia, but is different from the first embodiment in that the central air nozzle 63 and the like are omitted and rotating blades are provided. Therefore, the same symbols are attached to the same structures as the first embodiment below, and the differences from the first embodiment are mainly described.

As shown in FIG3 , a first rotating blade 76 and a second rotating blade 77 are provided on the outer wall of the inner cylinder nozzle 61. The rotating blades 76 and 77 are provided in a plurality in the circumferential direction around the central axis CL. In addition, the constriction portion 68 and the concentrator 69 shown in FIG2A of the first embodiment are not provided between the inner cylinder nozzle 61 and the outer cylinder nozzle 62.

The first rotating blade 76 imparts rotation about the central axis CL to the pulverized fuel and primary air flowing in the outer cylinder nozzle 62. The second rotating blade 77 imparts rotation in the opposite direction to the first rotating blade 76, which is located downstream of the first rotating blade 76 in the flow direction of the primary air. In the inner cylinder nozzle 61, a fuel injection nozzle 65 as shown in FIG. 2B is provided, which is the same as the first embodiment.

The effects of this embodiment, in addition to the effects common to the first embodiment, also include the following. After the first rotating blade 76 imparts rotation around the central axis CL, the second rotating blade 77 imparts rotation in the opposite direction. Thus, when the outer cylinder nozzle 62 is supplied with micro-powder fuel and primary air for dedicated combustion of micro-powder fuel, the first rotating blade 76 guides the micro-powder fuel to the inner wall side of the outer cylinder nozzle 62 for fuel concentration. The second rotating blade 77 returns the rotation of the primary air imparted with rotation by the first rotating blade 76 to normal, thereby improving the flow of the primary air. When performing dedicated combustion of liquid ammonia fuel, the second rotating blade 77 located on the downstream side can be used as a flame protector.

[Third embodiment] Next, the third embodiment of the present invention is described using FIG. 4A and FIG. 4B. This embodiment is the same as the first embodiment in that it performs dedicated combustion of fine powder fuel and dedicated combustion of liquid ammonia, but is different from the first embodiment in that the central air nozzle 63 and the like are omitted and the liquid ammonia fuel is sprayed from the outside of the outer cylinder nozzle 62. Therefore, the same symbols are attached to the same structures as the first embodiment below, and the differences from the first embodiment are mainly described.

As shown in FIG. 4A , the inner cylinder nozzle 61 supplies only oil fuel. An oil fuel injection nozzle (not shown) for injecting oil fuel is provided in the inner cylinder nozzle 61. An oil flow path is formed in the oil fuel injection nozzle, and atomized oil fuel is injected into the furnace 11 from a plurality of injection holes. The oil fuel injection nozzle may be a dual-fluid nozzle or a pressure spray nozzle.

A concentrator 69 is provided on the outer periphery of the inner cylinder nozzle 61. The function of the concentrator 69 is the same as that of the first embodiment.

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

A liquid ammonia spray nozzle 82 is provided in the liquid ammonia spray nozzle 80. As shown in FIG. 4B , a liquid ammonia flow path is formed in the liquid ammonia spray nozzle 82, and atomized liquid ammonia fuel is sprayed from a plurality of spray holes 82a toward the furnace 11. The liquid ammonia spray nozzle 82 sprays the liquid ammonia fuel as a pressure spray.

The effects of this embodiment include the following in addition to the effects common to the first embodiment. The ammonia fuel can be used as a liquid by the liquid ammonia injection nozzle 82, so the calorific value required for the dedicated combustion of the ammonia fuel can be ensured. As in the first embodiment, the oil fuel is supplied from the inner cylinder nozzle 61, thereby starting the burner. When the dedicated combustion of the liquid ammonia fuel is performed, the liquid ammonia fuel is supplied from the liquid ammonia nozzle 80 and the primary air is supplied from the outer cylinder nozzle 62. At this time, the pulverized fuel is not supplied from the outer cylinder nozzle 62. When the dedicated combustion of the pulverized fuel is performed, the pulverized fuel and the primary air supplied from the outer cylinder nozzle 62 are used to perform the dedicated combustion of the pulverized fuel. At this time, the flame of the fine powder fuel is maintained by the flame retainer 71. The liquid ammonia fuel is not supplied from the liquid ammonia nozzle 80. The liquid ammonia nozzle 80 is provided in plurality, and is configured to spray the liquid ammonia fuel from the outer peripheral side of the outer cylinder nozzle 62 in the direction toward the center axis CL, thereby realizing a structure for ammonia-only combustion without significantly changing the structure of the fine powder fuel burner. In addition, the flame of the ammonia flame can be maintained by the flame retainer 71, and it can also be configured to spray in a tangential direction to the center axis CL.

[Fourth embodiment] Next, the fourth embodiment of the present invention is described using Figures 5 to 10. This embodiment is the same as the third embodiment in that it performs dedicated combustion of fine powder fuel and dedicated combustion of liquid ammonia, but is different from the third embodiment in that a central air nozzle is provided. Therefore, the same symbols are attached to the same structures as the third embodiment below, and the differences from the third embodiment are mainly described.

The burner 21 of this embodiment has a central air nozzle (air nozzle) 63, which is located on the inner peripheral side of the outer tube nozzle 62 and the outer peripheral side of the inner tube nozzle 61, and is provided to cover the inner tube nozzle 61. Combustion air and liquid ammonia are supplied to the central air nozzle 63. The front end of the central air nozzle 63 is located upstream of the front end of the inner tube nozzle 61.

The first rotating blade 76 and the second rotating blade 77 are provided on the outer periphery of the inner cylinder nozzle 61. The first rotating blade 76 and the second rotating blade 77 are the same as those in the second embodiment (FIG. 3). In addition, a concentrator (coal powder concentration regulator) 69 shown in FIG. 2 may be provided instead of the first rotating blade 76 and the second rotating blade 77. In this case, as shown in FIG. 2, a constriction portion 68 is provided on the downstream side of the front end of the center air nozzle 63 and on the upstream side of the concentrator 69.

Unlike the third embodiment shown in Fig. 4A, the liquid ammonia nozzle 80 is disposed parallel to the central axis CL. However, the liquid ammonia nozzle 80 may be tilted toward the central axis CL as in the third embodiment.

<During dedicated combustion of pulverized fuel> During dedicated combustion of pulverized coal fuel, 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 cylinder nozzle 62 to form a flame FL1 of pulverized fuel. The flame of pulverized fuel is maintained by the second flame retainer 71. At this time, oil is not supplied to the inner cylinder nozzle 61 (stop), air and liquid ammonia are not supplied to the center air nozzle 63 (stop), and liquid ammonia is not supplied to the liquid ammonia nozzle 80 (stop).

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

<When exclusively burning liquid ammonia fuel> When exclusively burning liquid ammonia fuel, the operation of the grinder 31 (see FIG. 1 ) is stopped to stop the supply of the fine powder fuel. Then, as shown in FIG. 7 , liquid ammonia is supplied from the liquid ammonia supply source 50 to the liquid ammonia nozzle 80, and together with the combustion air supplied from the central air nozzle 63, a flame FL2 caused by the liquid ammonia fuel is formed. In the outer cylinder nozzle 62, no fine powder fuel and air are supplied (rest).

By supplying combustion air from the central air nozzle 63, the flame FL2 is formed not toward the peripheral side but along the central axis CL of the burner 21. For example, as shown in FIG8 , when the central air nozzle 63 is not provided and the combustion air does not flow from the central axis side of the burner 21, the flame FL2 is moved toward the peripheral side by the flow of the peripheral air as shown by the arrow A1.

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

10, liquid ammonia may be supplied to the central air nozzle passage 64 connected to the upstream side of the central air nozzle 63. This can promote mixing of liquid ammonia and air compared to the case where the liquid ammonia nozzle 80 is supplied to the central air nozzle 63 as shown in FIG9.

The effects of this embodiment include the following in addition to the effects common to the third embodiment. During the dedicated combustion of liquid ammonia, combustion air is supplied from the central air nozzle 63, so that the flame LF2 formed by the liquid ammonia nozzle 80 is formed not toward the outer peripheral side but along the central axis CL of the burner 21.

During the dedicated combustion of liquid ammonia, liquid ammonia is supplied to the central air nozzle 63, thereby promoting ignition at the outlet of the burner 21.

The front end of the central air nozzle 63 is positioned upstream of the front end of the inner tube nozzle 61, thereby preventing the space for the pulverized coal to flow between the inner tube nozzle 61 and the outer tube nozzle 62 from becoming narrower as much as possible. This can avoid the combustion performance of the pulverized coal from being impaired during the dedicated combustion.

In the above-mentioned embodiments, the boiler of the present invention is described as a boiler using solid fuel as fuel. As the solid fuel used in the boiler, coal, biomass fuel, petroleum coke (PC: Petroleum Coke) fuel, petroleum residue, etc. are used.

In addition, in each of the above-mentioned embodiments, the following effects are exerted. In the case of a wall-burning boiler in which multiple vertical sections and multiple horizontal rows of burners are arranged on the wall of the boiler, a boiler in which 24 burners are arranged in three vertical sections (H, M, L) and four horizontal rows on the front wall (F) and rear wall (R) of the furnace, respectively, is described as an example.

Among the 6-stage burners, one stage can be stopped, and the rated output of the boiler can be obtained by using the remaining 5 stages, and the stop stages can be switched in turn. Here, if any burner that can only burn a single type of fuel is arranged in a specific stage, the fuel mixed combustion rate during a certain operation period set for the boiler will naturally become fixed. It is difficult to cope with the operation of adjusting the mixed combustion rate by scheduling and supplying multiple fuels.

Furthermore, for example, if the output obtained by using ammonia fuel is lower than the output obtained by using pulverized fuel, the output of the entire boiler will naturally decrease when mixed combustion or even ammonia combustion is performed.

Even if a burner that can obtain the same output is used, if the ignition performance or flame stability of the burner is poor, there is a risk that unburned components will be generated or NOx will increase.

According to the burner 21 shown in the above-mentioned embodiments, in any mode of dedicated combustion of pulverized fuel or dedicated combustion of liquid ammonia, there will be no problem in the ignition property of the fuel or the stability of the flame, the output of the burner can be made the same, and there will be no generation of unburned components or increase in NOx.

Therefore, the dedicated combustion mode of the micronized fuel and the dedicated combustion mode of the liquid ammonia can be switched independently between FH, FM, FL, RH, RM, and RL, so that the mixed combustion rate of the fuel in a certain operation period can be achieved, which can be used flexibly.

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

A burner according to one aspect of the present invention comprises: an inner cylinder nozzle (61) extending along a central axis (CL) and supplying liquid ammonia fuel or oil fuel into a furnace; a first flame retainer (67) for retaining the flame of the liquid ammonia fuel or oil fuel supplied from the inner cylinder nozzle; an outer cylinder nozzle (62) extending along the central axis and arranged to cover the inner cylinder nozzle. A nozzle for supplying powdered fuel and/or primary air into the aforementioned furnace; and a second flame retainer (71) for maintaining the flame of the aforementioned powdered fuel supplied from the aforementioned outer tube nozzle, the aforementioned inner tube nozzle having a fuel injection nozzle (65) forming an ammonia flow path for the aforementioned liquid ammonia fuel to flow, and an oil flow path for the aforementioned oil fuel of a system different from the ammonia flow path to flow.

A fuel injection nozzle is provided in the inner cylinder nozzle, and liquid ammonia fuel and oil fuel can be injected separately. In this way, not only oil fuel can be used when starting the burner, but also dedicated combustion of liquid ammonia fuel and dedicated combustion of fine powder fuel can be performed. Ammonia fuel can be used as a liquid through the fuel injection nozzle, so the calorific value required for dedicated combustion of ammonia fuel can be ensured. When starting the burner, oil fuel is selectively supplied from the inner cylinder nozzle to start the burner. After the burner is started, the supply of oil fuel is stopped. When performing dedicated combustion of liquid ammonia fuel, liquid ammonia fuel is selectively supplied from the inner cylinder nozzle and primary air is supplied from the outer cylinder nozzle. At this time, the flame of the liquid ammonia fuel is maintained by the first flame retainer. At this time, the powder fuel is not supplied from the outer cylinder nozzle. When the dedicated combustion of the powder fuel is performed, the dedicated combustion of the powder fuel is performed by the powder fuel and primary air supplied from the outer cylinder nozzle. At this time, the flame of the powder fuel is maintained by the second flame retainer. At this time, the liquid ammonia fuel is not supplied from the inner cylinder nozzle.

In one aspect of the burner of the present invention, there is an air nozzle (63) which is located on the inner peripheral side of the outer tube nozzle and the outer peripheral side of the inner tube nozzle and is arranged to cover the inner tube nozzle to supply air for combustion. The air nozzle is provided with the first flame protector.

An air nozzle is provided on the outer peripheral side of the inner cylinder nozzle, thereby supplying combustion air to the liquid ammonia fuel or oil fuel supplied from the inner cylinder nozzle. Furthermore, by providing a first flame protector on the air nozzle, the flame of the liquid ammonia fuel or oil fuel can be stabilized.

A burner in one aspect of the present invention comprises: a first rotating blade (76) which is arranged on the outer periphery of the inner cylinder nozzle and is imparted with rotation around the central axis; and a second rotating blade (77) which is arranged on the outer periphery of the inner cylinder nozzle and is located on the downstream side of the flow direction of the primary air relative to the first rotating blade and is imparted with rotation in a direction opposite to that of the first rotating blade.

After the first rotating blade is used to impart rotation around the central axis, the second rotating blade is used to impart rotation in the opposite direction. Thus, when the outer cylinder nozzle is supplied with pulverized fuel and primary air, the pulverized fuel is guided to the inner wall of the outer cylinder nozzle by the first rotating blade to perform fuel concentration. The second rotating blade returns the rotation of the primary air imparted with rotation by the first rotating blade to the normal state, thereby improving the flow of the primary air. When performing dedicated combustion of liquid ammonia fuel, the second rotating blade located on the downstream side can be used as the first flame protector.

A burner according to one aspect of the present invention comprises: an inner cylinder nozzle extending along a central axis and supplying oil fuel into a furnace; an outer cylinder nozzle extending along the aforementioned central axis and arranged to cover the aforementioned inner cylinder nozzle and supplying micro powder fuel and/or primary air into the aforementioned furnace; a flame retainer for retaining the flame of the aforementioned micro powder fuel supplied from the aforementioned outer cylinder nozzle; and a liquid ammonia nozzle (80) for supplying liquid ammonia fuel into the aforementioned furnace, the aforementioned liquid ammonia nozzle having a liquid ammonia injection nozzle (82) for injecting the aforementioned liquid ammonia fuel.

Ammonia fuel can be used as a liquid by the liquid ammonia injection nozzle, so the calorific value required for the dedicated combustion of ammonia fuel can be ensured. Liquid ammonia fuel can be pressure-sprayed by the liquid ammonia injection nozzle. The burner can be started by supplying oil fuel from the inner cylinder nozzle. After the burner is started, the supply of oil fuel is stopped. When the dedicated combustion of liquid ammonia fuel is performed, liquid ammonia fuel is supplied from the liquid ammonia nozzle and primary air is supplied from the outer cylinder nozzle. At this time, pulverized fuel is not supplied from the outer cylinder nozzle. When the dedicated combustion of pulverized fuel is performed, the pulverized fuel and primary air supplied from the outer cylinder nozzle are used to perform the dedicated combustion of pulverized fuel. At this time, the flame of the powdered fuel is maintained by the flame protector. Liquid ammonia fuel is not supplied from the liquid ammonia nozzle.

In the burner of one aspect of the present invention, the liquid ammonia nozzle is provided in plural, and each of the liquid ammonia nozzles sprays the liquid ammonia fuel from the outer peripheral side of the outer cylinder nozzle in a direction toward the central axis.

A plurality of liquid ammonia nozzles are provided, and the liquid ammonia fuel is sprayed from the outer peripheral side of the outer cylinder nozzle in the direction toward the central axis, thereby realizing a structure for ammonia-only combustion without significantly changing the structure of the burner for fine powder fuel. In addition, the ammonia flame can be maintained by a flame retainer, so that the flame can be sprayed in a tangential direction to the central axis.

In one aspect of the burner of the present invention, an air nozzle is provided, which is located on the inner peripheral side of the outer tube nozzle and the outer peripheral side of the inner tube nozzle and is arranged to cover the inner tube nozzle to supply air for combustion.

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 instead of toward the periphery.

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

Liquid ammonia is supplied to the air nozzle, thereby promoting ignition at the burner outlet.

In the burner of one aspect of the present invention, the front end of the air nozzle is located upstream of the front end of the inner tube nozzle.

The front end of the air nozzle is positioned upstream of the front end of the inner tube nozzle, thereby preventing the space for the pulverized coal to flow between the inner tube nozzle and the outer tube nozzle from becoming narrower as much as possible. This can avoid the combustion performance of the pulverized coal from being impaired during the dedicated combustion.

In one aspect of the burner of the present invention, rotating blades and/or a restricting portion and/or a pulverized coal concentration regulator are provided on the outer periphery of the inner cylinder nozzle, between the front end of the inner cylinder nozzle and the front end of the air nozzle.

Rotating blades and/or a restricting portion and/or a pulverized coal concentration regulator (PCC: Pulverized Coal Concentrator) are provided on the outer periphery of the inner cylinder nozzle between the front end of the inner cylinder nozzle and the front end of the air nozzle, thereby making it possible to construct the burner compactly.

In one aspect of the burner of the present invention, there is an air nozzle passage connected to the upstream side of the aforementioned air nozzle, and the air nozzle is supplied with combustion air. Liquid ammonia is supplied to the air nozzle passage.

By supplying liquid ammonia to the air nozzle passage, ignition at the burner outlet can be promoted. Also, by supplying liquid ammonia to the air nozzle passage, mixing of liquid ammonia and air can be promoted compared to the case where liquid ammonia is supplied to the air nozzle.

A boiler according to one aspect of the present invention comprises any one of the above-mentioned burners.

The operating method of a burner in one aspect of the present invention comprises: an inner cylinder nozzle extending along the central axis and supplying liquid ammonia fuel or oil fuel into a furnace; a first flame retainer, which retains the flame of the liquid ammonia fuel or oil fuel supplied from the inner cylinder nozzle; an outer cylinder nozzle extending along the central axis and arranged to cover the inner cylinder nozzle and supplying powder fuel and/or primary air into the furnace; and a second flame retainer, which retains the flame of the powder fuel supplied from the outer cylinder nozzle, the inner cylinder nozzle having a fuel injection nozzle, the fuel injection nozzle forming a nozzle for supplying the liquid ammonia fuel flow. The operating method comprises: an ammonia flow path for movement, and an oil flow path for flow of the aforementioned oil fuel in a system different from the ammonia flow path, and comprises: a starting process, which supplies the oil fuel to the aforementioned oil flow path of the aforementioned fuel injection nozzle to start the burner; an ammonia-only combustion process, which does not supply the aforementioned fine powder fuel to the aforementioned outer cylinder nozzle, but supplies liquid ammonia fuel to the aforementioned ammonia flow path of the aforementioned fuel injection nozzle to carry out ammonia-only combustion; and a fine powder fuel-only combustion process, which does not supply the liquid ammonia fuel to the aforementioned ammonia flow path of the aforementioned fuel injection nozzle, but supplies the aforementioned fine powder fuel and the aforementioned primary air to the aforementioned outer cylinder nozzle to carry out fine powder fuel-only combustion.

The operating method of a burner in one aspect of the present invention comprises: an inner cylinder nozzle extending along a central axis and supplying oil fuel into a furnace; an outer cylinder nozzle extending along the aforementioned central axis and arranged to cover the aforementioned inner cylinder nozzle and supplying fine powder fuel and/or primary air into the aforementioned furnace; a flame retainer that retains the flame of the fine powder fuel supplied from the aforementioned outer cylinder nozzle; and a liquid ammonia nozzle that supplies liquid ammonia fuel into the aforementioned furnace, the aforementioned liquid ammonia nozzle having a liquid for spraying the aforementioned liquid ammonia fuel. The ammonia injection nozzle, the operation method, comprises: a starting process, which supplies oil fuel to the aforementioned inner cylinder nozzle to start the injector; an ammonia-only combustion process, which does not supply the aforementioned fine powder fuel to the aforementioned outer cylinder nozzle, but supplies liquid ammonia fuel to the aforementioned liquid ammonia injection nozzle of the aforementioned liquid ammonia injection nozzle to perform ammonia-only combustion; and a fine powder fuel-only combustion process, which does not supply liquid ammonia fuel to the aforementioned liquid ammonia injection nozzle, but supplies the aforementioned fine powder fuel and the aforementioned primary air to the aforementioned outer cylinder nozzle to perform fine powder fuel-only combustion.

10: Boiler 11: Furnace 12: Combustion gas passage 13: Flue 20: Combustion device 21: Burner 22: Powder fuel supply pipe 23: Bellows (air regulator) 24: Air duct (air passage) 25: Additional air vent 26: Additional air passage 31: Grinding mill (crusher) 32: Injection fan (FDF) 41: Gas passage 42: Air preheater 43: Denitrification device 44: Dust collector 45: Induction fan (IDF) 46: Desulfurization device 47: Chimney 50: Liquid ammonia supply source 61: Inner cylinder nozzle 62: Outer cylinder nozzle 63: Center air nozzle (air nozzle) 64: Center air nozzle channel (air nozzle channel) 65: Fuel injection nozzle 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 retainer 68: Restriction section 68a: Upstream side inclined section 68b: Downstream side inclined section 69: Concentrator 69a: Upstream side inclined section 69b: Downstream side inclined section 69c: Cylinder section 71: Second flame retainer (flame retainer) 73: Secondary air flow path 74: Tertiary air flow path 74a: Rotor 76: First rotating blade 77: Second rotating blade 80: Liquid ammonia nozzle 82: Liquid ammonia injection nozzle 82a: Injection hole 101: Furnace wall 102: Superheater 103: Reheater 104: Economizer

[Fig. 1] is a schematic diagram showing the structure of a boiler according to the first embodiment of the present invention. [Fig. 2A] is a longitudinal sectional view of the burner of Fig. 1. [Fig. 2B] is a longitudinal sectional view of a fuel injection nozzle used in the burner of Fig. 2A. [Fig. 3] is a longitudinal sectional view of a burner according to the second embodiment of the present invention. [Fig. 4A] is a longitudinal sectional view of a burner according to the third embodiment of the present invention. [Fig. 4B] is a longitudinal sectional view of a fuel injection nozzle used in the burner of Fig. 4A. [Fig. 5] is a longitudinal sectional view of a burner according to the fourth embodiment of the present invention. [Fig. 6] is a longitudinal sectional view of the burner shown in Fig. 5 during the dedicated combustion of pulverized coal. [Fig. 7] is a longitudinal sectional view of the burner shown in Fig. 5 when the liquid ammonia is exclusively burned. [Fig. 8] is a longitudinal sectional view of the burner of the comparative example. [Fig. 9] is a longitudinal sectional view of the burner of a modified example when the liquid ammonia is exclusively burned shown in Fig. 7. [Fig. 10] is a longitudinal sectional view of the burner of another modified example when the liquid ammonia is exclusively burned shown in Fig. 7.

11: Fireplace

21: Burner

61: Inner tube nozzle

62: External nozzle

63: Central air nozzle (air nozzle)

67: No. 1 Flame Protector

68: Reduction section

68a: Upstream side slope

68b: Downstream side slope

69: Concentrator

69a: Upstream side slope

69b: Downstream side slope

69c: cylindrical part

71: The second flame protector (flame protector)

73: Secondary air flow path

74: Tertiary air flow path

74a: Rotator

101: Fireplace wall

CL: Center axis

Claims (7)

A burner comprises: an inner cylinder nozzle extending along a central axis and supplying oil fuel into a furnace; an outer cylinder nozzle extending along the central axis and arranged to cover the inner cylinder nozzle and supplying fine powder fuel and/or primary air into the furnace; a flame retainer for retaining the flame of the fine powder fuel supplied from the outer cylinder nozzle; and a liquid ammonia nozzle for supplying liquid ammonia fuel into the furnace. The aforementioned liquid ammonia nozzle has a liquid ammonia injection nozzle for injecting the aforementioned liquid ammonia fuel. The aforementioned liquid ammonia nozzle is provided in plural, and each of the aforementioned liquid ammonia nozzles injects the aforementioned liquid ammonia fuel from the outer peripheral side of the aforementioned outer cylinder nozzle toward the aforementioned central axis. It also has an air nozzle, which is located on the inner peripheral side of the aforementioned outer cylinder nozzle and the outer peripheral side of the aforementioned inner cylinder nozzle, and is provided to cover the inner cylinder nozzle to supply air for combustion. A burner as described in claim 1, wherein liquid ammonia is supplied to the aforementioned air nozzle. The burner as described in claim 1, wherein the front end of the air nozzle is located upstream of the front end of the inner tube nozzle. The burner as described in claim 3, wherein a rotating blade and/or a restricting portion and/or a pulverized coal concentration regulator are provided on the outer periphery of the inner tube nozzle, between the front end of the inner tube nozzle and the front end of the air nozzle. The burner as described in claim 1 is provided with an air nozzle passage connected to the upstream side of the aforementioned air nozzle, the air nozzle is supplied with combustion air, and the air nozzle passage is supplied with liquid ammonia. A boiler having a burner according to any one of claims 1 to 5. A method for operating a burner, wherein the burner comprises: an inner cylinder nozzle extending along a central axis and supplying oil fuel into a furnace; an outer cylinder nozzle extending along the central axis and arranged to cover the inner cylinder nozzle and supplying fine powder fuel and/or primary air into the furnace; a flame retainer for maintaining the flame of the fine powder fuel supplied from the outer cylinder nozzle; and a liquid ammonia nozzle for supplying liquid ammonia fuel into the furnace, wherein the liquid ammonia nozzle comprises a liquid ammonia spray nozzle for spraying the liquid ammonia fuel, wherein the liquid ammonia nozzle is provided in plural, and each of the liquid ammonia nozzles is provided from the outer peripheral side of the outer cylinder nozzle toward the central axis. The burner is provided with an air nozzle located on the inner circumference of the outer cylinder nozzle and the outer circumference of the inner cylinder nozzle, and is arranged to cover the inner cylinder nozzle to supply combustion air. The operation method of the burner includes: a dedicated combustion process for fine powder fuel, which stops supplying liquid ammonia fuel from a liquid ammonia supply source, supplies fine powder fuel and primary air from the outer cylinder nozzle, and forms a flame caused by fine powder fuel; and a dedicated combustion process for ammonia fuel, which stops supplying fine powder fuel, supplies liquid ammonia fuel from a liquid ammonia supply source to the liquid ammonia nozzle, and causes the liquid ammonia fuel to form a flame together with the combustion air supplied from the air nozzle.

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