Ammonia combustion burner, boiler, and boiler operation method

Abstract

To suppress NOx generation amount in an ammonia combustion burner.SOLUTION: An ammonia combustion burner related to at least one embodiment of this disclosure is an ammonia combustion burner for burning ammonia fuel by a boiler, and includes: a combustion air nozzle for ejecting combustion air; a first ammonia injection nozzle disposed in the combustion air nozzle to inject ammonia fuel in the combustion air nozzle; and a flame holder disposed downstream of the first ammonia injection nozzle. The combustion air nozzle is configured to eject partially premixed fuel of part of the combustion air and the ammonia fuel injected from the first ammonia injection nozzle and remaining part of the combustion air.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to an ammonia-fired burner, a boiler, and a method of operating a boiler. [Background technology]

[0002] Boilers in which ammonia is supplied as fuel to a furnace are known. For example, the boiler disclosed in Patent Document 1 performs ammonia co-firing, in which ammonia is burned together with coal in the furnace. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2020-41748 Summary of the Invention [Problem to be solved by the invention]

[0004] When ammonia is burned in a burner, the amount of NOx generated is more susceptible to the local air ratio at the interface between the fuel and combustion air in the combustion field than when other fuels are burned. Therefore, in order to suppress the amount of NOx generated, it is important to control the local air ratio at the interface between the ammonia and combustion air in the combustion field.

[0005] In view of the above circumstances, at least one embodiment of the present disclosure has an object to suppress the amount of NOx generated in an ammonia combustion burner. [Means for solving the problem]

[0006] (1) An ammonia combustion burner according to at least one embodiment of the present disclosure includes: 1. An ammonia combustion burner for burning ammonia fuel in a boiler, comprising: a combustion air nozzle for ejecting combustion air; a first ammonia injection nozzle disposed inside the combustion air nozzle for injecting the ammonia fuel inside the combustion air nozzle; a flame stabilizer disposed downstream of the first ammonia injection nozzle; Equipped with The combustion air nozzle is configured to inject partially premixed fuel of a portion of the combustion air and the ammonia fuel injected from the first ammonia injection nozzle, and the remainder of the combustion air.

[0007] (2) A boiler according to at least one embodiment of the present disclosure includes: a furnace including a furnace wall; an ammonia combustion burner having the configuration of (1) above, provided on the furnace wall; Equipped with.

[0008] (3) A boiler according to at least one embodiment of the present disclosure includes: a furnace including a furnace wall; an ammonia combustion burner having the configuration of (1) above, provided on the furnace wall; an other-fuel burner provided at a position different from the ammonia combustion burner on the furnace wall and configured to burn a fuel other than the ammonia fuel; Equipped with.

[0009] (4) A boiler according to at least one embodiment of the present disclosure includes: a furnace including a furnace wall; an ammonia combustion burner having the configuration of (1) above, provided on the furnace wall; an ignition detection sensor that detects ignition inside the combustion air nozzle; a control device that controls an injection amount of the ammonia fuel injected from the first ammonia injection nozzle based on a detection result of the ignition detection sensor; Equipped with The control device an injection amount calculation unit that calculates an injection amount of the ammonia fuel to be injected from the first ammonia injection nozzle based on a detection result of the ignition detection sensor; an adjustment unit that adjusts the injection amount so that the injection amount becomes the injection amount calculated by the injection amount calculation unit; It has.

[0010] (5) A boiler according to at least one embodiment of the present disclosure includes: a furnace including a furnace wall; an ammonia combustion burner having the configuration of (1) above, provided on the furnace wall; a control device that controls an injection amount of the ammonia fuel injected from the first ammonia injection nozzle; Equipped with the ammonia fuel supplied to the first ammonia injection nozzle is liquid ammonia, the ammonia combustion burner is provided with a temperature sensor for detecting a metal temperature; The control device an injection amount calculation unit that calculates an injection amount of the ammonia fuel to be injected from the first ammonia injection nozzle based on a detection result of the temperature sensor; an adjustment unit that adjusts the injection amount so that the injection amount becomes the injection amount calculated by the injection amount calculation unit; It has.

[0011] (6) A method for operating a boiler according to at least one embodiment of the present disclosure includes: 1. A method for operating a boiler supplied with ammonia fuel, comprising: The boiler comprises: a furnace including a furnace wall; an ammonia combustion burner having the configuration of (1) above, provided on the furnace wall; an ignition detection sensor that detects ignition inside the combustion air nozzle; Including, calculating an injection amount of the ammonia fuel to be injected from the first ammonia injection nozzle based on a detection result of the ignition detection sensor; adjusting the injection amount to the injection amount calculated in the calculating step; Equipped with.

[0012] (7) A method for operating a boiler according to at least one embodiment of the present disclosure includes: 1. A method for operating a boiler supplied with ammonia fuel, comprising: The boiler comprises: a furnace including a furnace wall; an ammonia combustion burner having the configuration of (1) above, provided on the furnace wall; Including, the ammonia fuel supplied to the first ammonia injection nozzle is liquid ammonia, the ammonia combustion burner is provided with a temperature sensor for detecting a metal temperature; calculating an injection amount of the ammonia fuel to be injected from the first ammonia injection nozzle based on a detection result of the temperature sensor; adjusting the injection amount to the injection amount calculated in the calculating step; Equipped with. [Effects of the Invention]

[0013] According to at least one embodiment of the present disclosure, the amount of NOx generated in an ammonia combustion burner can be suppressed. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a schematic configuration diagram showing a boiler system including a boiler that uses ammonia fuel and a fuel other than ammonia fuel as main fuels according to an embodiment of the present invention. [Figure 2] FIG. 2 is a schematic diagram showing the structure of a first ammonia burner. [Figure 3] FIG. 2 is a schematic diagram for explaining a contact state between ammonia fuel and combustion air. [Figure 4] 1 is a graph for explaining an air ratio at a contact surface between ammonia fuel and combustion air. [Figure 5] FIG. 2 is a schematic diagram showing the structure of a second ammonia burner. [Figure 6] FIG. 2 is a schematic diagram showing the structure of a first ammonia burner provided with a protrusion. [Figure 7A] FIG. 1 is a cross-sectional view schematically illustrating an example of the structure of a pressure spray nozzle. [Figure 7B] FIG. 7B is a schematic diagram of a backplate disposed inside the pressure spray nozzle shown in FIG. 7A. [Figure 8] FIG. 1 is a cross-sectional view schematically showing an example of the structure of a two-fluid spray nozzle. [Figure 9] FIG. 4 is a diagram for explaining adjustment of the amount of ammonia injected from the first ammonia injection nozzle. [Figure 10] 10 is a flowchart showing a flow of a process for controlling the injection amount of ammonia fuel injected from a first ammonia injection nozzle based on the detection result of the ignition detection sensor. [Figure 11] 10 is a flowchart showing a flow of a process for controlling the injection amount of ammonia fuel injected from the first ammonia injection nozzle based on the detection result of the temperature sensor. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, several embodiments of the present disclosure will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of components described as embodiments or shown in the drawings are merely illustrative examples and are not intended to limit the scope of the present disclosure. For example, expressions expressing relative or absolute arrangement such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial" not only express such an arrangement exactly, but also express a state in which there is a relative displacement with a tolerance or an angle or distance to the extent that the same function is obtained. For example, expressions such as "identical," "equal," and "homogeneous" that indicate that something is in an equal state not only indicate a state of strict equality, but also indicate a state in which there is a tolerance or a difference to the extent that the same function is obtained. For example, expressions representing shapes such as a square shape or a cylindrical shape not only represent shapes such as a square shape or a cylindrical shape in the strict geometric sense, but also represent shapes including uneven portions, chamfered portions, etc., to the extent that the same effect can be obtained. On the other hand, the expressions "comprise," "include," "have," "includes," or "have" of one element are not exclusive expressions that exclude the presence of other elements.

[0016] <1. Overall configuration of boiler system 1> FIG. 1 is a schematic diagram showing the configuration of a boiler system 1 according to this embodiment, which includes boilers that use ammonia fuel and a fuel other than ammonia fuel as their main fuels.

[0017] The boiler 10 included in the boiler system 1 of this embodiment is a boiler that can burn ammonia fuel and other fuels other than ammonia fuel using a burner and generate superheated steam by heat exchange of the heat generated by this combustion with feedwater or steam. As the other fuel, for example, a solid fuel such as biomass fuel or coal is used. The solid fuel is, for example, pulverized coal fuel obtained by finely pulverizing coal. The ammonia fuel is a liquid or gas containing ammonia.

[0018] Boiler 10 has a furnace 11, combustion devices 20 and 50, and a combustion gas passage 12. Furnace 11 has a hollow rectangular cylindrical shape and is installed vertically. Furnace wall 101, which forms the inner wall surface of furnace 11, is composed of multiple heat transfer tubes and fins that connect the heat transfer tubes together, and recovers heat generated by fuel combustion by heat exchange with water and steam circulating inside the heat transfer tubes, while suppressing a temperature rise in furnace wall 101.

[0019] The combustion devices 20 and 50 are installed in a lower region of the furnace 11. In this embodiment, the combustion device 20 is configured to inject pulverized coal fuel into the interior of the furnace 11. Also, the combustion device 50 is configured to inject ammonia fuel into the interior of the furnace 11.

[0020] The combustion device 20 has a plurality of burners 21 attached to the furnace wall 101, and the combustion device 50 has a plurality of ammonia burners (ammonia combustion burners) 51. An injection nozzle (not shown) configured to inject pulverized coal fuel into the furnace 11 is provided at the tip of each burner 21. Each ammonia burner 51 is also provided with an ammonia injection nozzle (for example, a first ammonia injection nozzle 521 and a second ammonia injection nozzle 522 shown in FIG. 3). When a liquid ammonia injection method is adopted in which liquid ammonia fuel is injected into the furnace 11, the ammonia injection nozzle may be a two-fluid injection nozzle configured to atomize and inject liquid ammonia using an atomizing fluid such as steam, or may be a one-fluid injection nozzle configured to inject only liquid ammonia fuel. When an ammonia gas injection method is adopted in which gaseous ammonia fuel is injected into the furnace 11, the ammonia injection nozzle may be a gas injection nozzle.

[0021] The burners 21 and ammonia burners 51 are arranged at equal intervals along the circumferential direction of the furnace 11 (for example, four burners installed at each corner of the rectangular furnace 11) as one set, and are arranged in multiple rows along the vertical direction. In the example of FIG. 1, one set of burners 21 is arranged in two rows, and one set of ammonia burners 51 is arranged in four rows. For convenience of illustration, only two burners of one set are shown in FIG. 1, and each set is designated by a symbol. issue The furnace shape, 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. Furthermore, the combustion method in the furnace 11 of this embodiment is a swirling combustion method in which burners are installed in corners and a spirally swirling flame is formed inside the furnace 11, but other combustion methods may also be used. Depending on the combustion method employed, the shape of the furnace 11 and the arrangement of the multiple burners 21 and multiple ammonia burners 51 may all be changed as appropriate. Another example of a combustion method is an opposed combustion method in which burners are installed on both of a pair of opposing furnace walls of the furnace 11.

[0022] The burners 21 of the combustion device 20 are connected to a plurality of mills (pulverizers) 31A and 31B (hereinafter, sometimes collectively referred to as "mills 31") via a plurality of pulverized coal fuel supply pipes 22A and 22B (hereinafter, sometimes collectively referred to as "pulverized coal fuel supply pipes 22"). The mill 31 is, for example, a vertical roller mill having a pulverizing table (not shown) supported therein so as to be rotatable, and a plurality of pulverizing rollers (not shown) supported above the pulverizing table so as to be rotatable in conjunction with the rotation of the pulverizing table. The solid fuel pulverized by the cooperation of the pulverizing rollers and the pulverizing table is transported to a classifier (not shown) provided in the mill 31 by primary air (carrier gas, oxidizing gas) supplied to the mill 31. The classifier classifies the pulverized coal fuel into pulverized coal fuel having a particle size equal to or smaller than that suitable for combustion in the burners 21 and coarse pulverized coal fuel having a particle size larger than that. The pulverized coal fuel passes through the classifier and is supplied to the burner 21 together with primary air via the pulverized coal fuel supply pipe 22. The coarse pulverized coal fuel that does not pass through the classifier falls onto the grinding table inside the mill 31 due to its own weight and is re-pulverized.

[0023] The above-mentioned primary air (carrier gas, oxidizing gas) supplied to the mill 31 is delivered to the mill 31 from a primary air fan (PAF) 33, which takes in outside air, via an air pipe 30. The air pipe 30 includes a hot air induction pipe 30A through which hot air, which has been heated by an air heater (air preheater) 42 and is part of the air delivered from the primary air fan 33, flows, a cold air induction pipe 30B through which cold air, which is close to room temperature and has not passed through the air heater 42 and is part of the air delivered from the primary air fan 33, flows, and a carrier gas flow path 30C through which the hot air and cold air join together and flow.

[0024] The ammonia burner 51 of the combustion device 50 is connected to an ammonia fuel supply unit 90. The ammonia fuel supply unit 90 of this embodiment includes an ammonia tank 91 and an ammonia fuel supply pipe 92 for supplying ammonia fuel (e.g., liquid ammonia) stored in the ammonia tank 91 to the combustion device 50 of the boiler 10. When the ammonia gas injection method is adopted, the ammonia fuel supply unit 90 may be provided with a vaporizer (not shown) for vaporizing the liquid ammonia. Furthermore, when the liquid ammonia injection method is adopted, the ammonia fuel supply unit 90 may further include an atomizing fluid supply pipe (not shown) for supplying an atomizing fluid for atomizing the liquid ammonia to the combustion device 50.

[0025] An air register (air box) 23 is provided outside the furnace 11 at the installation position of the burner 21 and the ammonia burner 51, and one end of an air duct (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: Forced Draft Fan) 32. 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 to the ammonia burner 51 as combustion air (oxidizing gas), and then introduced into the furnace 11.

[0026] 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 sometimes collectively referred to as "superheaters 102"), reheaters 103A and 103B (hereinafter sometimes collectively referred to as "reheaters 103"), and a coal economizer 104 as heat exchangers for recovering heat from the combustion gas, and heat is exchanged between the combustion gas generated in the furnace 11 and feedwater or steam flowing inside each heat exchanger. Note that the arrangement and shape of each heat exchanger are not limited to those shown in FIG. 1.

[0027] A flue 13 is connected to the downstream side of the combustion gas passage 12, and discharges the combustion gas from which heat has been recovered by the heat exchanger. An air preheater (air heater) 42 is provided between the flue 13 and the air duct 24, and heat is exchanged between the air flowing through the air duct 24 and the combustion gas flowing through the flue 13, thereby heating the primary air supplied to the mill 31 and the combustion air supplied to the burner 21 and the ammonia burner 51, thereby recovering further heat from the combustion gas after heat exchange with water and steam.

[0028] Furthermore, a denitration device 43 may be provided in the flue 13 at a position upstream of the air preheater 42. The denitration device 43 supplies a reducing agent, such as ammonia or urea water, which has the effect of reducing nitrogen oxides, to the combustion gas flowing through the flue 13, and promotes the reaction between the nitrogen oxides (NOx) in the combustion gas to which the reducing agent has been supplied and the reducing agent by the catalytic action of a denitration catalyst provided in the denitration device 43, thereby removing and reducing the nitrogen oxides in the combustion gas. A gas duct 41 is connected to the flue 13 downstream of the air preheater 42. The gas duct 41 is provided with environmental equipment such as a dust collector 44, such as an electrostatic precipitator, that removes ash and the like from the combustion gas, and a desulfurization equipment 46 that removes sulfur oxides, as well as an induced draft fan (IDF) 45 that guides the exhaust gas to these environmental equipment. The downstream end of the gas duct 41 is connected to a chimney 47, and the combustion gas that has been treated in the environmental equipment is discharged to the outside of the system as exhaust gas.

[0029] In the boiler 10, when the multiple mills 31 are driven, pulverized and classified pulverized coal fuel is supplied together with primary air to the burner 21 via the pulverized coal fuel supply pipe 22. Also, ammonia fuel is supplied from the ammonia fuel supply unit 90 to the ammonia burner 51. Furthermore, secondary air heated by the air preheater 42 is supplied from the air duct 24 via the air register 23 to the burner 21 and the ammonia burner 51. The burner 21 injects a pulverized coal fuel mixture, which is a mixture of pulverized coal fuel and primary air, into the furnace 11, and also injects secondary air into the furnace 11. The pulverized coal fuel mixture injected into the furnace 11 ignites and reacts with the secondary air to form a flame. The ammonia burner 51 injects ammonia fuel and combustion air into the furnace 11. The ammonia fuel injected into the furnace 11 reacts with the combustion air and burns. High-temperature combustion gas generated by the combustion of pulverized coal fuel and ammonia fuel rises within the furnace 11 and flows into the combustion gas passage 12. The timing at which the ammonia fuel is injected into the furnace 11 may be after the temperature inside the furnace 11 has risen to a certain temperature due to the combustion of the pulverized coal fuel. For example, after the mono-combustion of the pulverized coal fuel is performed at the start of the boiler 10, the ammonia fuel may be injected into the furnace 11, and ammonia co-combustion of the ammonia fuel and the pulverized coal fuel may be performed. Further thereafter, the injection of the pulverized coal fuel may be stopped, and the mono-combustion of ammonia may be performed. In addition, in this embodiment, air is used as the oxidizing gas (primary air, secondary air, combustion 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.

[0030] The combustion gas that has flowed into the combustion gas passage 12 exchanges heat with water and steam in a superheater 102, a reheater 103, and an economizer 104 arranged inside the combustion gas passage 12, and is then discharged into the flue 13, where nitrogen oxides are removed in a denitration device 43, and the gas exchanges heat with primary air, secondary air, and combustion air in an air preheater 42, and is then discharged into the gas duct 41, where ash and the like are removed in a dust collector 44, and sulfur oxides are removed in a desulfurization device 46, and the gas is then discharged to the outside of the system from a chimney 47. Note that the arrangement of the heat exchangers in the combustion gas passage 12 and the arrangement of the devices from the flue 13 to the gas duct 41 with respect to the flow of the combustion gas do not necessarily have to be in the order described above.

[0031] The boiler of the present disclosure is not limited to the above-described embodiment. Instead of or in addition to coal, biomass fuel, petroleum coke (PC) fuel, petroleum residue, etc. may be used as the solid fuel for the boiler. Furthermore, the boiler fuel to be combined with ammonia fuel is not limited to solid fuels, but also includes petroleum fuels such as heavy oil, light oil, and heavy oil, and liquid fuels such as industrial wastewater. Also, gaseous fuels such as natural gas, various petroleum gases, and by-product gases generated in steelmaking processes can be used. Furthermore, the present invention can be applied to a multi-fuel boiler that uses a combination of these various fuels. In the following description, ammonia fuel will also be simply referred to as ammonia.

[0032] As described above, the boiler 10 according to at least one embodiment of the present disclosure comprises a furnace 11 including a furnace wall 101, an ammonia burner 51 (described in detail later) provided in the furnace wall 101, and a burner 21 provided at a position different from the ammonia burner 51 on the furnace wall 101 and serving as a pulverized coal burner for burning pulverized coal. This makes it possible to suppress the amount of NOx emitted from the boiler 10 according to at least one embodiment of the present disclosure. The burner 21 may be a fuel burner that burns fuel other than ammonia fuel. Furthermore, the boiler 10 according to at least one embodiment of the present disclosure may be a dual-fuel boiler that burns ammonia fuel and a fuel other than ammonia fuel, or may be an ammonia-only boiler that burns only ammonia fuel.

[0033] (Regarding the amount of NOx generated when ammonia is burned in a burner) When ammonia is burned in a burner, the amount of NOx generated is more susceptible to the local air ratio at the interface between the fuel and combustion air in the combustion field than when other fuels are burned. Therefore, in order to suppress the amount of NOx generated, it is important to control the local air ratio at the interface between the ammonia and combustion air in the combustion field. Therefore, in the boiler 10 according to this embodiment, the ammonia burner 51 is configured as follows to suppress the amount of NOx generated.

[0034] (Regarding the first ammonia burner 51A) FIG. 2 is a schematic side cross-sectional view showing the structure of a first ammonia burner 51A according to one embodiment of the ammonia burner 51 according to some embodiments, and a schematic front view of the first ammonia burner 51A as viewed from the downstream side in the flow direction of the combustion air along the central axis Ax. FIG. 6 is a schematic side cross-sectional view showing the structure of a first ammonia burner 51A provided with a protrusion 57, and a schematic front view of the first ammonia burner 51A as viewed from the downstream side in the flow direction of the combustion air along the central axis Ax.

[0035] The first ammonia burner 51A shown in Fig. 6 has the same configuration as the first ammonia burner 51A shown in Fig. 2, except that it is provided with a protruding portion 57. The protruding portion 57 will be described in detail later. The first ammonia burner 51A shown in Figures 2 and 6 is equipped with a combustion air nozzle 54 for ejecting combustion air. The first ammonia burner 51A shown in Figures 2 and 6 is equipped with a first ammonia injection nozzle 521 that is disposed inside the combustion air nozzle 54 and that injects ammonia fuel inside the combustion air nozzle 54. The first ammonia burner 51A shown in Figures 2 and 6 is equipped with a flame stabilizer 56 that is disposed downstream of the first ammonia injection nozzle 521. In the first ammonia burner 51A shown in Figures 2 and 6, the flame stabilizer 56 is, for example, a diffuser-type flame stabilizer 56A having a hollow truncated cone shape. 2 and 6 may include a second ammonia injection nozzle 522 for injecting ammonia fuel downstream of the flame stabilizer 56. Note that the second ammonia injection nozzle 522 is not essential to the first ammonia burner 51A shown in FIGS.

[0036] 2 and 6, the combustion air nozzle 54 is a duct having a rectangular cross section when viewed along the central axis Ax, and is formed so that the flow path cross-sectional area decreases toward the downstream side while maintaining the rectangular cross-sectional shape near the downstream end. Note that the cross-sectional shape of the combustion air nozzle 54 is not limited to a rectangular shape. In the first ammonia burner 51A shown in FIGS. 2 and 6, the combustion air nozzle 54 has an opening 54a for ejecting combustion air.

[0037] The first ammonia burner 51A shown in FIGS. 2 and 6 is configured to premix a portion of the combustion air and the ammonia fuel injected from the first ammonia injection nozzle 521 in the combustion air nozzle . Therefore, in the first ammonia burner 51A shown in FIGS. 2 and 6, the first ammonia injection nozzle 521 is arranged upstream of the outlet opening 54a of the combustion air nozzle 54 in order to ensure an area for premixing a part of the combustion air and the ammonia fuel injected from the first ammonia injection nozzle 521 in the combustion air nozzle 54, as will be described below. In the first ammonia burner 51A shown in Figures 2 and 6, a plurality of first ammonia injection nozzles 521 are arranged at intervals in the circumferential direction around the central axis Ax. In the example shown in Figures 2 and 6, four first ammonia injection nozzles 521 are arranged at intervals in the circumferential direction around the central axis Ax.

[0038] As described above, in the first ammonia burner 51A shown in FIGS. 2 and 6, the combustion air nozzle 54 is configured to inject partially premixed fuel of a part of the combustion air and the ammonia fuel injected from the first ammonia injection nozzle 521, and the remainder of the combustion air.

[0039] 2 and 6, a gap is formed between the opening 54a of the combustion air nozzle 54 and the outer edge of the flame stabilizer 56. The gap is a passage for ejecting at least a portion of the partially premixed fuel and the remainder of the combustion air from the gap. It should be noted that the first ammonia burner 51A shown in FIGS. 2 and 6 is provided with a diffuser-type flame stabilizer 56A, so that the entire amount of the partially premixed fuel is ejected from the gap.

[0040] 2 and 6, the ammonia supplied to the first ammonia burner 51A is, for example, gaseous ammonia fuel (ammonia gas). Note that the ammonia fuel supplied to the first ammonia burner 51A may be liquid ammonia fuel, as will be described later.

[0041] In the first ammonia burner 51A shown in Figures 2 and 6, the second ammonia injection nozzle 522 is arranged coaxially with the combustion air nozzle 54 and is configured to inject ammonia into the furnace 11 from multiple injection holes 52h.

[0042] 2 and 6, ammonia injected from the first ammonia injection nozzle 521 as shown by arrow a in FIGS. 2 and 6 and a portion of the combustion air as shown by dashed arrow b in FIGS. 2 and 6 are premixed in the combustion air nozzle 54 to generate partially premixed fuel. This partially premixed fuel is injected into the furnace 11 from a gap between the opening 54a of the combustion air nozzle 54 and the outer edge of the flame stabilizer 56 as shown by arrow c. The remainder of the combustion air not used for premixing with ammonia is injected into the furnace 11 from the gap as shown by dashed arrow d in FIGS. 2 and 6. In the first ammonia burner 51A shown in FIGS. 2 and 6, ammonia supplied to the second ammonia injection nozzle 522 is injected into the furnace 11 from a plurality of injection holes 52h as indicated by arrows e in FIGS.

[0043] The first ammonia burner 51A shown in FIGS. 2 and 6 includes a partition wall 625 that separates a flow path 541 for the partially premixed fuel from a flow path 542 for the remainder of the combustion air. The partition wall 625 is, for example, a first ammonia burner 51A. of It is a cylindrical member coaxial with the central axis Ax. An inner circumferential surface 625a of the partition wall 625 defines a flow path 541 for the partially premixed fuel, and an outer circumferential surface 625b of the partition wall 625 forms a flow path 542 for the remainder of the combustion air between itself and an inner circumferential surface 54i of the combustion air nozzle 54.

[0044] The combustion air partially premixed with ammonia flows from the upstream open end of partition wall 625 into the inside of partition wall 625, that is, into flow path 541 for partially premixed fuel, as shown by dashed arrow b in FIGS. The partially premixed fuel flows out from the downstream open end of the partition wall 625 into the furnace 11, as indicated by the dashed arrow c in FIGS.

[0045] The remainder of the combustion air that has not been used for premixing with ammonia flows outside the partition wall 625 and flows out into the furnace 11 as shown by the dashed arrows f and d in FIGS. 2 and 6. This makes it possible to prevent more combustion air than necessary from being premixed with ammonia fuel inside the combustion air nozzle 54, making it easier to stabilize the air ratio in the partially premixed fuel.

[0046] The reason why the amount of NOx generated is suppressed in the ammonia burner 51 according to some embodiments will be described below. FIG. 3 is a schematic diagram for explaining the contact state between ammonia fuel and combustion air. target This is a diagram. Fig. 4 is a graph for explaining the air ratio at the contact surface between ammonia fuel and combustion air. The graph in Fig. 4 shows how the air ratio changes from the fuel side to the combustion air side in the region where the injected ammonia fuel or partially premixed fuel contacts the injected combustion air. In the graph in Fig. 4, the dashed line indicates the graph line for the case where ammonia fuel is subjected to diffusion combustion, and the solid line indicates the graph line for the case where partially premixed fuel premixed in the combustion air nozzle 54 is combusted with combustion air.

[0047] 3, the upper side of the drawing, with the central axis Ax of the ammonia burner 51X along the flow of combustion air as a boundary, shows a case in which partially premixed fuel premixed in the combustion air nozzle 54 and combustion air are injected and burned (partial premixed combustion), similar to the above-mentioned first ammonia burner 51A. Also, the lower side of the drawing, with the central axis Ax as a boundary, shows a case in which ammonia fuel is subjected to diffusion combustion.

[0048] As shown in the lower part of Fig. 3, when ammonia fuel is subjected to diffusion combustion, the entire amount of combustion air and the ammonia fuel are diffusely mixed. Therefore, the contact surface S1 between the injected ammonia fuel F1 and the injected combustion air A1 becomes relatively wide. In addition, the local air ratio at this contact surface S1 is considered to exceed 1, creating an atmosphere in which NOx is likely to be generated (see Fig. 4).

[0049] As shown in the upper part of Figure 3, when partially premixed fuel premixed in the combustion air nozzle 54 is combusted with combustion air, part of the combustion air is premixed with ammonia fuel in the combustion air nozzle 54 and injected into the combustion field. The ammonia fuel is then diffusively mixed with the remainder of the combustion air in the furnace 11. In this case, the flow rate of the combustion air to be diffusively mixed is reduced by the amount used for premixing, so the contact surface S2 between the injected partially premixed fuel F2 and the injected combustion air A2 is narrower than in the case of diffusive combustion. In addition, the local air ratio at this contact surface S2 is lower than in the case of diffusive combustion of ammonia fuel (see Figure 4). Therefore, when partially premixed fuel premixed in the combustion air nozzle 54 is combusted with combustion air, the amount of NOx generated can be reduced compared to when ammonia fuel is subjected to diffusion combustion.

[0050] Therefore, the first ammonia burner 51A shown in FIGS. 2 and 6 can suppress the amount of NOx generated.

[0051] 2 and 6, the partially premixed fuel and the remainder of the combustion air are ejected from the gap between the opening 54a of the combustion air nozzle 54 and the outer edge of the flame stabilizer 56, thereby narrowing the contact surface between the partially premixed fuel and the combustion air when they are diffused and mixed. This makes it possible to suppress the amount of NOx generated in the first ammonia burner 51A.

[0052] 2 and 6, the first ammonia burner 51A is provided with a diffuser-type flame stabilizer 56A, which enables flame stabilization in the vicinity of the first ammonia burner 51A and prevents the contact surface between the partially premixed fuel and the combustion air from expanding during diffusion mixing. This makes it possible to suppress the amount of NOx generated in the first ammonia burner 51A.

[0053] In the first ammonia burner 51A shown in FIGS. 2 and 6, at least a part of the flame stabilizer 56 is preferably located within the injection range of the ammonia fuel injected by the first ammonia injection nozzle 521. As a result, it is expected that the ammonia fuel injected from the first ammonia injection nozzle 521 will cool the flame stabilizer 56, which will contribute to suppressing a temperature rise in the flame stabilizer 56.

[0054] In the first ammonia burner 51A shown in FIGS. 2 and 6, by providing the second ammonia injection nozzle 522, the ammonia fuel injected from the second ammonia injection nozzle 522 can be subjected to diffusion combustion.

[0055] In the first ammonia burner 51A shown in FIGS. 2 and 6, ammonia may be injected only from the first ammonia injection nozzle 521, only from the second ammonia injection nozzle 522, or from both the first ammonia injection nozzle 521 and the second ammonia injection nozzle 522, depending on the required combustion amount of the first ammonia burner 51A due to the operating conditions of the boiler 10, for example, when the load on the boiler 10 is changed.

[0056] (Regarding the second ammonia burner 51B) FIG. 5 is a schematic side cross-sectional view showing the structure of a second ammonia burner 51B of one embodiment of the ammonia burner 51 according to some embodiments, and a schematic front view of the second ammonia burner 51B as viewed from the downstream side in the flow direction of the combustion air along the central axis Ax. The second ammonia burner 51B shown in FIG. 5 has the same configuration as the first ammonia burner 51A shown in FIG. 2, except that the structure of the flame stabilizer 56 is different from that of the first ammonia burner 51A shown in FIG. That is, the second ammonia burner 51B shown in Fig. 5 is provided with a combustion air nozzle 54 for ejecting combustion air. The second ammonia burner 51B shown in Fig. 5 is provided with a first ammonia injection nozzle 521 that is disposed inside the combustion air nozzle 54 and that injects ammonia fuel inside the combustion air nozzle 54. The second ammonia burner 51B shown in Fig. 5 is provided with a flame stabilizer 56 that is disposed downstream of the first ammonia injection nozzle 521. In the second ammonia burner 51B shown in Fig. 5, the flame stabilizer 56 is, for example, a swirler-type flame stabilizer 56B that is provided with a plurality of swirl vanes. The first ammonia burner 51A shown in Fig. 2 may include a second ammonia injection nozzle 522 for injecting ammonia fuel downstream of the flame stabilizer 56. Note that the second ammonia injection nozzle 522 is not essential to the first ammonia burner 51A shown in Fig. 2.

[0057] The second ammonia burner 51B shown in FIG. 5 is configured to premix a portion of the combustion air and the ammonia fuel injected from the first ammonia injection nozzle 521 in the combustion air nozzle . Therefore, in the second ammonia burner 51B shown in FIG. 5, the first ammonia injection nozzle 521 is arranged upstream of the outlet opening 54a of the combustion air nozzle 54 in order to ensure an area for premixing a portion of the combustion air and the ammonia fuel injected from the first ammonia injection nozzle 521 within the combustion air nozzle 54. In the second ammonia burner 51B shown in Fig. 5, a plurality of first ammonia injection nozzles 521 are arranged at intervals in the circumferential direction around the central axis Ax. In the example shown in Fig. 5, four first ammonia injection nozzles 521 are arranged at intervals in the circumferential direction around the central axis Ax.

[0058] As described above, in the second ammonia burner 51B shown in FIG. 5, the combustion air nozzle 54 is configured to inject a partially premixed fuel of a part of the combustion air and the ammonia fuel injected from the first ammonia injection nozzle 521, and the remainder of the combustion air.

[0059] 5, an opening 54a of the combustion air nozzle 54 forms a gap with the outer edge of the flame stabilizer 56. The gap is a passage for ejecting at least a portion of the partially premixed fuel and the remainder of the combustion air from the gap. In addition, since the second ammonia burner 51B shown in FIG. 5 is provided with a swirler-type flame stabilizer 56B, most of the partially premixed fuel is absorbed by the swirler-type flame stabilizer 56B. B The partially premixed fuel is injected from the openings between the plurality of swirl vanes, and a portion of the partially premixed fuel is injected from the gaps.

[0060] 5, the ammonia fuel supplied to the second ammonia burner 51B is, for example, gaseous ammonia fuel (ammonia gas). Note that the ammonia supplied to the second ammonia burner 51B may be liquid ammonia fuel, as will be described later.

[0061] In the second ammonia burner 51B shown in FIG. 5, the second ammonia injection nozzle 522 is arranged coaxially with the combustion air nozzle 54 and is configured to inject ammonia fuel into the furnace 11 from a plurality of injection holes 52h.

[0062] In the second ammonia burner 51B shown in FIG. 5, similarly to the first ammonia burner 51A shown in FIG. 2, the combustion air nozzle 54 is configured to inject a partially premixed fuel of a part of the combustion air and ammonia fuel injected from the first ammonia injection nozzle 521, and the remainder of the combustion air, so that the amount of NOx generated can be suppressed.

[0063] 5, a part of the partially premixed fuel and the remaining part of the combustion air are ejected from the gap between the opening 54a of the combustion air nozzle 54 and the outer edge of the flame stabilizer 56, thereby narrowing the contact surface between the partially premixed fuel and the combustion air when they are diffused and mixed. This makes it possible to suppress the amount of NOx generated in the second ammonia burner 51B.

[0064] 5 is equipped with a swirler-type flame stabilizer 56B, which enables flame stabilization in the vicinity of the first ammonia burner 51A and prevents the contact surface between the partially premixed fuel and the combustion air from expanding during diffusion mixing, thereby reducing the amount of NOx generated in the second ammonia burner 51B.

[0065] 5, the flame stabilizer 56 is a swirler-type flame stabilizer 56B, and therefore the metal temperature of the flame stabilizer 56 can be suppressed compared to the diffuser-type flame stabilizer 56A. This is because the swirler-type flame stabilizer 56B has a smaller heat receiving area from the combustion gas in the furnace 11 and the flame it forms, compared to the diffuser-type flame stabilizer 56A, and has a larger contact area with the fluid (partially premixed fuel, combustion air) flowing inside the combustion air nozzle 54.

[0066] In the second ammonia burner 51B shown in FIG. 5, at least a part of the flame stabilizer 56 is preferably located within the injection range of the ammonia fuel injected by the first ammonia injection nozzle 521. As a result, it is expected that the flame stabilizer will be cooled by the ammonia fuel injected from the first ammonia injection nozzle 521, which will contribute to suppressing the temperature rise of the flame stabilizer.

[0067] In the second ammonia burner 51B shown in FIG. 5, by providing the second ammonia injection nozzle 522, the ammonia fuel injected from the second ammonia injection nozzle 522 can be subjected to diffusion combustion.

[0068] In the second ammonia burner 51B shown in FIG. 5, ammonia may be injected only from the first ammonia injection nozzle 521, only from the second ammonia injection nozzle 522, or from both the first ammonia injection nozzle 521 and the second ammonia injection nozzle 522, depending on the required combustion amount of the second ammonia burner 51B due to the operating conditions of the boiler 10, for example, when the load on the boiler 10 is changed.

[0069] (Regarding temperature suppression of flame stabilizer 56) 2, the flame stabilizer 56 is a diffuser-type flame stabilizer 56A, and therefore the metal temperature of the flame stabilizer 56 tends to be higher than that of a swirler-type flame stabilizer 56B. This is because the diffuser-type flame stabilizer 56A has a larger heat receiving area for radiant heat from the combustion gas in the furnace 11 and the flame it forms, compared to the swirler-type flame stabilizer 56B, and because the contact area with the fluid (fuel, partially premixed fuel, combustion air) flowing inside the combustion air nozzle 54 is smaller. Therefore, the first ammonia burner 51A may be provided with protruding portions (fins) 57 that are connected to the flame stabilizer 56 and protrude toward the upstream side of the flame stabilizer 56, as shown in FIG.

[0070] As shown in Fig. 6, for example, protrusion 57 is a plate-like member whose upstream end is connected to the surface of diffuser-type flame stabilizer 56A facing upstream, and which is formed to protrude toward the upstream side of flame stabilizer 56. A plurality of protrusions 57 are arranged, for example, around central axis Ax at intervals in the circumferential direction. In the example shown in Fig. 6, four protrusions 57 are arranged around central axis Ax at intervals in the circumferential direction. In the first ammonia burner 51A shown in FIG. 6, the protruding portion 57 comes into contact with the partially premixed fuel and combustion air premixed in the combustion air nozzle 54 and is cooled, thereby making it possible to suppress a temperature rise in the flame stabilizer 56.

[0071] (When liquid ammonia is sprayed) As described above, the ammonia burner 51 according to some embodiments may be configured to inject liquid ammonia fuel. In this case, nozzle tips (atomizers) capable of spraying liquid ammonia fuel may be attached to the tips of the first ammonia injection nozzle 521 and the second ammonia injection nozzle 522. FIG. 7A is a cross-sectional view schematically showing an example of the structure of the pressure spray nozzle 525. As shown in FIG. FIG. 7B is a schematic diagram of a backplate 525a positioned within the pressure atomizing nozzle 525 shown in FIG. 7A. FIG. 8 is a cross-sectional view showing a schematic example of the structure of the two-fluid spray nozzle 526. As shown in FIG.

[0072] The nozzle tips attached to the ends of the first ammonia injection nozzle 521 and the second ammonia injection nozzle 522 may be, for example, a pressure atomizing nozzle 525 as shown in FIG. 7A or a two-fluid atomizing nozzle 526 as shown in FIG. 8.

[0073] 7A, when the liquid ammonia passes through a back plate arranged inside, the flow direction is changed so that the liquid ammonia has a radial velocity component, and a swirl force is applied to the liquid ammonia fuel sprayed from the pressure spray nozzle 525. As a result, the liquid ammonia fuel is sprayed from the pressure spray nozzle 525 in, for example, a cone shape.

[0074] For example, in a two-fluid spray nozzle 526 as shown in FIG. 8, liquid ammonia fuel is atomized by an atomizing fluid supplied separately from the fuel, and then sprayed from the two-fluid spray nozzle 526. When a two-fluid spray nozzle 526 as shown in FIG. 8 is used for the first ammonia injection nozzle 521 and the second ammonia injection nozzle 522, superheated steam, air, nitrogen, or the like is used as the atomizing fluid.

[0075] As described above, by spraying liquid ammonia fuel from the ammonia burner 51 according to some embodiments, the flame stabilizer 56 and the like can be cooled by the latent heat of vaporization of the liquid ammonia fuel injected from, for example, the first ammonia injection nozzle 521. This makes it possible to suppress a rise in the temperature of the flame stabilizer 56 and the like.

[0076] (Regarding adjustment of the amount of ammonia injected from the first ammonia injection nozzle 521) In the boiler 10 equipped with the ammonia burner 51 according to some of the above-described embodiments, the amount of ammonia injected from the first ammonia injection nozzle 521 may be adjusted, for example, as described below. FIG. 9 is a diagram for explaining adjustment of the amount of ammonia injected from the first ammonia injection nozzle 521 in the ammonia burner 51 according to some embodiments. The ammonia burner 51 shown in FIG. 9 is the first ammonia burner 51A shown in FIG. 2, but may be the second ammonia burner 51B shown in FIG. 5 or the first ammonia burner 51A shown in FIG.

[0077] The boiler 10 including the ammonia burner 51 according to some embodiments includes a control device 900 for controlling the amount of ammonia injected from the first ammonia injection nozzle 521. The control device 900 according to some embodiments includes a controller 901 and an adjustment unit 95 .

[0078] The controller 901 includes a processor 901a that executes various arithmetic processes and a memory 901b that non-temporarily or temporarily stores various data processed by the processor. The processor is realized by a CPU, a GPU, an MPU, a DSP, various other arithmetic devices, or a combination of these. The memory is realized by a ROM, a RAM, a flash memory, or a combination of these. The controller 901 may be configured to control the boiler 10. The controller 901 may be configured to control the boiler system 1.

[0079] The controller 901 includes a functional block, an injection amount calculation unit 902. A processor 901a of the controller 901 functions as the injection amount calculation unit 902 by executing a program stored in a memory.

[0080] The adjustment unit 95 is, for example, a first flow rate adjustment valve 95A for adjusting the injection amount of ammonia fuel injected from the first ammonia injection nozzle 521. The adjustment unit 95 may include a second flow rate adjustment valve 95B for adjusting the injection amount of ammonia fuel injected from the second ammonia injection nozzle 522, and a third flow rate adjustment valve 95C for adjusting the supply amount of combustion air supplied to the combustion air nozzle 54.

[0081] The ammonia burner 51 according to some embodiments may include a temperature sensor 96 for detecting the metal temperature of the ammonia burner 51. The temperature sensor 96 may be, for example, a thermocouple, and may be attached to a metal portion in the combustion air nozzle 54 at a position relatively close to the opening 54a. The temperature sensor 96 may be attached to detect the temperature of the partition wall 625, for example, as shown in FIG. 9, or may be attached to detect the temperature in the vicinity of the downstream end of the first ammonia injection nozzle 521. The temperature sensor 96 may also be attached to detect the temperature of the flame stabilizer 56. The temperature sensor 96 may be installed to detect temperatures at locations other than the above-mentioned several detection locations. The temperature sensor 96 only needs to be installed to detect the temperature at at least one of these detection locations. The temperature sensor 96 functions as an ignition detection sensor 98 when used to detect ignition within the combustion air nozzle 54 as described below. The ammonia burner 51 according to some embodiments is provided with a temperature sensor 96 that detects the metal temperature of the combustion air nozzle 54, and therefore, as will be described later, it becomes possible to manage the metal temperature of the combustion air nozzle 54.

[0082] The ammonia burner 51 according to some embodiments may include a pressure sensor 97 for detecting the pressure inside the combustion air nozzle 54. Note that the pressure sensor 97 functions as an ignition detection sensor 98 when used to detect ignition inside the combustion air nozzle 54 as described below. As will be described later, if the pressure sensor 97 is used as the ignition detection sensor 98, it is sufficient that the pressure sensor 97 be able to detect pressure fluctuations of the combustion air inside the combustion air nozzle 54, and therefore the pressure sensor 97 does not necessarily have to be placed inside the combustion air nozzle 54.

[0083] In the boiler 10 including the ammonia burner 51 according to some embodiments, the detection signals from the temperature sensor 96 and the pressure sensor 97 are configured to be input to the controller 901 . In a boiler 10 including an ammonia burner 51 according to some embodiments, the first flow rate control valve 95A, the second flow rate control valve 95B, and the third flow rate control valve 95C are each provided with an actuator (not shown) for adjusting the flow rate. In a boiler 10 including an ammonia burner 51 according to some embodiments, control signals for driving these actuators are configured to be output from a controller 901.

[0084] (When controlling the injection amount of ammonia fuel injected from the first ammonia injection nozzle 521 in order to suppress ignition inside the combustion air nozzle 54) In the boiler 10 including the ammonia burner 51 according to some embodiments, the injection amount of the ammonia fuel injected from the first ammonia injection nozzle 521 may be controlled based on the detection result of the ignition detection sensor 98.

[0085] Fig. 10 is a flowchart showing the flow of a process for controlling the injection amount of ammonia fuel injected from the first ammonia injection nozzle 521 based on the detection result of the ignition detection sensor 98. A program for executing the process shown in the flowchart of Fig. 10 is read from the memory 901b and executed by the processor 901a.

[0086] The method for operating the boiler 10 according to one embodiment includes step S10 of calculating the injection amount and step S20 of adjusting the injection amount.

[0087] Step S10 of calculating the injection amount is a step of calculating the injection amount of ammonia fuel to be injected from the first ammonia injection nozzle based on the detection result of the ignition detection sensor 98. In step S10 of calculating the injection amount, the injection amount calculation unit 902 of the controller 901 determines whether ignition has occurred inside the combustion air nozzle 54 based on the detection result of the ignition detection sensor 98. For example, in step S10 of calculating the injection amount, the injection amount calculation unit 902 may determine whether ignition has occurred inside the combustion air nozzle 54 from the temperature detected by the temperature sensor 96, a change in that temperature, etc. Also, for example, in step S10 of calculating the injection amount, the injection amount calculation unit 902 may determine whether ignition has occurred inside the combustion air nozzle 54 from the pressure of the combustion air supplied to the combustion air nozzle 54 detected by the pressure sensor 97, a change in that pressure, etc. When it is determined that ignition has occurred inside the combustion air nozzle 54, the injection amount calculation unit 902 sets, for example, the set value of the injection amount from the first ammonia injection nozzle 521 to an injection amount smaller than the current ammonia injection amount. Note that when the injection amount calculation unit 902 sets the set value of the injection amount from the first ammonia injection nozzle 521 to an injection amount smaller than the current ammonia injection amount, the injection amount calculation unit 902 may set the set value of the injection amount from the second ammonia injection nozzle 522 to an injection amount larger than the current ammonia injection amount by an amount equivalent to the decrease in the injection amount from the first ammonia injection nozzle 521.

[0088] Step S20 of adjusting the injection amount is a step of adjusting the injection amount from the first ammonia injection nozzle 521 so that it becomes the injection amount calculated in step S10 of calculating the injection amount. In step S20 of adjusting the injection amount, the processor 901a outputs a control signal to drive an actuator (not shown) of the first flow rate control valve 95A so that the injection amount becomes the injection amount calculated (set) in step S10 of calculating the injection amount. In the first flow rate control valve 95A, an actuator (not shown) receives the control signal and adjusts the flow rate of ammonia in the first flow rate control valve 95A. As a result, the injection amount of ammonia fuel injected from the first ammonia injection nozzle 521 is adjusted to the injection amount calculated (set) in step S10 of calculating the injection amount. This reduces the risk of backfire into the ammonia combustion burner 51. In addition, in step S20 of adjusting the injection amount, the processor 901a may output a control signal for driving an actuator (not shown) of the second flow rate control valve 95B so that the injection amount from the first ammonia injection nozzle 521 becomes the injection amount calculated (set) in step S10 of calculating the injection amount. In the second flow rate control valve 95B, an actuator (not shown) receives the control signal and adjusts the flow rate of ammonia in the second flow rate control valve 95B. As a result, the injection amount of ammonia fuel injected from the second ammonia injection nozzle 522 is adjusted to the injection amount calculated (set) in step S10 for calculating the injection amount.

[0089] That is, the boiler 10 including the ammonia burner 51 according to some embodiments includes an ignition detection sensor 98 that detects ignition inside the combustion air nozzle 54, and a control device 900 that controls the injection amount of ammonia fuel injected from the first ammonia injection nozzle 521 based on the detection result of the ignition detection sensor 98. The control device 900 includes an injection amount calculation unit 902 that calculates the injection amount of ammonia fuel injected from the first ammonia injection nozzle 521 based on the detection result of the ignition detection sensor 98, and an adjustment unit 95 that adjusts the injection amount so that it becomes the injection amount calculated by the injection amount calculation unit 902.

[0090] (When controlling the injection amount of ammonia fuel injected from the first ammonia injection nozzle 521 in order to suppress the metal temperature of the ammonia combustion burner 51) In the boiler 10 including the ammonia burner 51 according to some embodiments, the injection amount of the ammonia fuel injected from the first ammonia injection nozzle 521 may be controlled based on the detection result of the temperature sensor 96.

[0091] Fig. 11 is a flowchart showing the flow of a process for controlling the injection amount of ammonia fuel injected from the first ammonia injection nozzle 521 based on the detection result of the temperature sensor 96. A program for executing the process shown in the flowchart of Fig. 11 is read from the memory 901b and executed by the processor 901a.

[0092] The method for operating the boiler 10 according to one embodiment includes a step S50 of calculating the injection amount and a step S60 of adjusting the injection amount.

[0093] Step S10 of calculating the injection amount is a step of calculating the injection amount of the ammonia fuel to be injected from the first ammonia injection nozzle 521 based on the detection result of the temperature sensor 96. In step S10 of calculating the injection amount, the injection amount calculation unit 902 of the controller 901 monitors the detection result of the temperature sensor 96, i.e., the metal temperature detected by the temperature sensor 96. Then, for example, when the injection amount calculation unit 902 determines that the metal temperature detected by the temperature sensor 96 has exceeded a preset threshold, it sets the set value of the injection amount from the first ammonia injection nozzle 521 to an injection amount larger than the current ammonia injection amount. Note that when the injection amount calculation unit 902 sets the set value of the injection amount from the first ammonia injection nozzle 521 to an injection amount larger than the current ammonia injection amount, it may set the set value of the injection amount from the second ammonia injection nozzle 522 to an injection amount smaller than the current ammonia injection amount by an amount corresponding to the increase in the injection amount from the first ammonia injection nozzle 521.

[0094] For example, if the structure of the ammonia combustion burner 51 differs, the conditions and extent of damage (hereinafter referred to as burnout) to the tip of the combustion air nozzle 54, the flame stabilizer 56, and other components of the ammonia combustion burner 51 due to heat received from the combustion gas in the furnace 11 and the self-flame formed by the ammonia combustion burner 51 will differ. Therefore, in step S10 of calculating the injection amount, the injection amount calculation unit 902 may change the injection amount from the first ammonia injection nozzle 521 for suppressing the metal temperature depending on the structure of the ammonia combustion burner 51. Furthermore, in step S10 of calculating the injection amount, the injection amount calculation unit 902 may predict a change in the metal temperature from the metal temperature detected by the temperature sensor 96, and set the injection amount from the first ammonia injection nozzle 521 based on the predicted temperature change. When predicting a change in the metal temperature, the injection amount calculation unit 902 may take into consideration the combustion air ratio in the ammonia combustion burner 51, the structure of the ammonia combustion burner 51, the load on the boiler 10, etc.

[0095] Step S60 of adjusting the injection amount is a step of adjusting the injection amount from the first ammonia injection nozzle 521 so that it becomes the injection amount calculated in step S50 of calculating the injection amount. In step S60 of adjusting the injection amount, the processor 901a outputs a control signal to drive an actuator (not shown) of the first flow rate control valve 95A so that the injection amount becomes the amount calculated (set) in step S50 of calculating the injection amount. In the first flow rate control valve 95A, an actuator (not shown) receives the control signal and adjusts the flow rate of ammonia in the first flow rate control valve 95A. As a result, the injection amount of ammonia fuel injected from the first ammonia injection nozzle 521 is adjusted to the injection amount calculated (set) in step S50 of calculating the injection amount. This makes it possible to suppress an increase in the metal temperature of the ammonia combustion burner 51 and to suppress the occurrence of burnout. When suppressing the metal temperature of the ammonia combustion burner 51 by increasing the injection amount from the first ammonia injection nozzle 521 in this way, it is more effective to use liquid ammonia fuel as the ammonia fuel supplied to the first ammonia injection nozzle 521. The flame stabilizer 56 and the like can be cooled by the latent heat of vaporization of the liquid ammonia injected from the first ammonia injection nozzle 521. This makes it possible to more effectively suppress the temperature rise of the flame stabilizer 56 and the like. In step S60 of adjusting the injection amount, the processor 901a may output a control signal to drive an actuator (not shown) of the second flow rate control valve 95B so that the injection amount from the first ammonia injection nozzle 521 becomes the injection amount calculated (set) in step S50 of calculating the injection amount. In the second flow rate control valve 95B, an actuator (not shown) receives the control signal and adjusts the flow rate of ammonia in the second flow rate control valve 95B. As a result, the injection amount of ammonia fuel injected from the second ammonia injection nozzle 522 is adjusted to the injection amount calculated (set) in step S50 of calculating the injection amount.

[0096] As described above, the boiler 10 including the ammonia burner 51 according to some embodiments includes a control device 900 that controls the injection amount of ammonia fuel injected from the first ammonia injection nozzle 521. The ammonia fuel supplied to the first ammonia injection nozzle 521 may be liquid ammonia fuel. The ammonia combustion burner 51 includes a temperature sensor 96 that detects the metal temperature. The control device 900 includes an injection amount calculation unit 902 that calculates the injection amount of ammonia fuel injected from the first ammonia injection nozzle 521 based on the detection result of the temperature sensor 96, and an adjustment unit 95 that adjusts the injection amount so that it becomes the injection amount calculated by the injection amount calculation unit 902.

[0097] The present disclosure is not limited to the above-described embodiments, but also includes modifications to the above-described embodiments and appropriate combinations of these modifications.

[0098] The contents described in each of the above embodiments can be understood, for example, as follows. (1) The ammonia combustion burner 51 according to at least one embodiment of the present disclosure is an ammonia combustion burner 51 for burning ammonia fuel in the boiler 10. The ammonia combustion burner 51 according to at least one embodiment of the present disclosure includes a combustion air nozzle 54 for ejecting combustion air. The ammonia combustion burner 51 according to at least one embodiment of the present disclosure includes a first ammonia injection nozzle 521 that is disposed inside the combustion air nozzle 54 and for injecting ammonia fuel inside the combustion air nozzle 54. The ammonia combustion burner 51 according to at least one embodiment of the present disclosure includes a flame stabilizer 56 that is disposed downstream of the first ammonia injection nozzle 521. The combustion air nozzle 54 is configured to eject a partially premixed fuel of a portion of the combustion air and ammonia fuel injected from the first ammonia injection nozzle 521, and the remainder of the combustion air.

[0099] According to the above-mentioned configuration (1), it is easy to lower the local air ratio at the contact surface between the partially premixed fuel and the remainder of the combustion air in the combustion field compared to the local air ratio at the contact surface between the ammonia fuel and the combustion air in the combustion field when premixing is not performed. Furthermore, according to the above-mentioned configuration (1), compared to when premixing is not performed, the flow rate of the combustion air to be diffusively mixed is reduced by the amount used in advance for partial premixing, so that the contact surface between the combustion air and the partially premixed fuel during diffusive mixing can be narrowed. This makes it possible to suppress the amount of NOx generated in the ammonia combustion burner 51.

[0100] (2) In some embodiments, in the configuration of (1) above, the combustion air nozzle 54 may have an opening 54a through which the combustion air is ejected. The opening 54a may form a gap between the opening 54a and the outer edge of the flame stabilizer 56. The gap may be a passage through which at least a portion of the partially premixed fuel and the remainder of the combustion air are ejected from the gap.

[0101] According to the configuration (2) above, by ejecting at least a part of the partially premixed fuel and the remaining part of the combustion air from the gap, it is possible to narrow the contact surface between the combustion air and the partially premixed fuel during diffusive mixing, thereby suppressing the amount of NOx generated in the ammonia combustion burner 51.

[0102] (3) In some embodiments, in the configuration of (1) or (2) above, a partition wall 625 may be provided that separates the flow path 541 for the partially premixed fuel from the flow path 542 for the remainder of the combustion air.

[0103] According to the above configuration (3), it is possible to prevent more combustion air than necessary from being premixed with ammonia fuel inside the combustion air nozzle 54, and therefore it is easy to stabilize the air ratio in the partially premixed fuel.

[0104] (4) In some embodiments, in any of the configurations (1) to (3) above, the flame holder 56 may be a diffuser-type or swirler-type flame holder.

[0105] According to the above configuration (4), the flame can be stabilized in the vicinity of the ammonia combustion burner 51, so that it is possible to prevent the contact surface between the combustion air and the partially premixed fuel from expanding during diffusive mixing. This makes it possible to suppress the amount of NOx generated in the ammonia combustion burner 51.

[0106] (5) In some embodiments, in any of the configurations (1) to (4) above, at least a portion of the flame stabilizer 56 may be located within an injection range of the ammonia fuel injected by the first ammonia injection nozzle 521.

[0107] According to the configuration (5) above, it is expected that the flame stabilizer 56 will be cooled by the ammonia fuel injected from the first ammonia injection nozzle 521, which contributes to suppressing the temperature rise of the flame stabilizer 56.

[0108] (6) In some embodiments, in any of the configurations (1) to (5) above, the ammonia fuel supplied to the first ammonia injection nozzle 521 may be liquid ammonia fuel.

[0109] According to the above configuration (6), the flame stabilizer 56 and the like can be cooled by the latent heat of vaporization of the liquid ammonia fuel injected from the first ammonia injection nozzle 521. This makes it possible to suppress a rise in the temperature of the flame stabilizer 56 and the like.

[0110] (7) In some embodiments, in any of the configurations (1) to (6) above, a second ammonia injection nozzle 522 for injecting ammonia fuel downstream of the flame stabilizer 56 may be provided.

[0111] According to the above configuration (7), the ammonia fuel injected from the second ammonia injection nozzle 522 can be subjected to diffusion combustion.

[0112] (8) In some embodiments, any of the configurations (1) to (7) above may be provided with a protrusion 57 connected to the flame stabilizer 56 and protruding toward the upstream side of the flame stabilizer 56.

[0113] According to the configuration (8) above, the protruding portion 57 is cooled by convection, so that the temperature rise of the flame stabilizer 56 can be suppressed.

[0114] (9) In some embodiments, in any of the configurations (1) to (8) above, a temperature detection sensor (temperature sensor 96) that detects the metal temperature of the combustion air nozzle 54 may be provided.

[0115] According to the above configuration (9), it is possible to control the metal temperature of the combustion air nozzle 54.

[0116] (10) In some embodiments, any of the configurations (1) to (9) above may include an ignition detection sensor 98 that detects ignition inside the combustion air nozzle 54.

[0117] According to the configuration (10) above, even if the partially premixed fuel ignites inside the combustion air nozzle 54, this ignition can be detected, and the risk of backfire into the ammonia combustion burner 51 can be reduced.

[0118] (11) A boiler 10 according to at least one embodiment of the present disclosure comprises a furnace 11 including a furnace wall 101, and an ammonia combustion burner 51 having any of the configurations described above in (1) to (10) provided on the furnace wall 101.

[0119] According to the above configuration (11), the amount of NOx emitted from the boiler 10 equipped with the ammonia combustion burner 51 can be suppressed.

[0120] (12) A boiler 10 according to at least one embodiment of the present disclosure comprises a furnace 11 including a furnace wall 101, an ammonia combustion burner 51 having any of the configurations (1) to (10) above provided on the furnace wall 101, and a different fuel burner (burner 21) provided at a position different from the ammonia combustion burner 51 on the furnace wall 101 and burning a fuel other than ammonia fuel.

[0121] According to the configuration (12) above, the amount of NOx emitted from the boiler 10 can be suppressed.

[0122] (13) A boiler 10 according to at least one embodiment of the present disclosure includes a furnace 11 including a furnace wall 101, an ammonia combustion burner 51 having any of the configurations described above in (1) to (9) and provided on the furnace wall 101, an ignition detection sensor 98 that detects ignition inside the combustion air nozzle 54, and a control device 900 that controls the injection amount of ammonia fuel injected from the first ammonia injection nozzle 521 based on the detection result of the ignition detection sensor 98. The control device 900 includes an injection amount calculation unit 902 that calculates the injection amount of ammonia fuel injected from the first ammonia injection nozzle 521 based on the detection result of the ignition detection sensor 98, and an adjustment unit 95 that adjusts the injection amount so that the injection amount becomes the injection amount calculated by the injection amount calculation unit 902.

[0123] According to the above configuration (13), the risk of backfire into the ammonia combustion burner 51 can be reduced.

[0124] (14) A boiler 10 according to at least one embodiment of the present disclosure comprises a furnace 11 including a furnace wall 101, an ammonia combustion burner 51 having the configuration described in any one of (1) to (9) above and provided on the furnace wall 101, and a control device 900 that controls the injection amount of ammonia fuel injected from a first ammonia injection nozzle 521. The ammonia fuel supplied to the first ammonia injection nozzle 521 is liquid ammonia. The ammonia combustion burner 51 is equipped with a temperature sensor 96 that detects a metal temperature. The control device 900 comprises an injection amount calculation unit 902 that calculates the injection amount of ammonia fuel injected from the first ammonia injection nozzle 521 based on the detection result of the temperature sensor 96, and an adjustment unit 95 that adjusts the injection amount so that the injection amount becomes the injection amount calculated by the injection amount calculation unit 902.

[0125] According to the above configuration (14), the metal temperature of the ammonia combustion burner 51 can be suppressed, and the occurrence of burnout can be suppressed.

[0126] (15) A method for operating a boiler 10 according to at least one embodiment of the present disclosure is a method for operating a boiler 10 to which ammonia fuel is supplied. The boiler 10 includes a furnace 11 including a furnace wall 101, an ammonia combustion burner 51 having any of the configurations (1) to (8) above provided on the furnace wall 101, and an ignition detection sensor 98 that detects ignition inside the combustion air nozzle 54. The method for operating a boiler 10 according to at least one embodiment of the present disclosure includes step S10 of calculating an injection amount of ammonia fuel to be injected from the first ammonia injection nozzle 821 based on a detection result of the ignition detection sensor 98, and step S20 of adjusting the injection amount so that the injection amount becomes the injection amount calculated in step S10.

[0127] According to the above configuration (15), the risk of backfire into the ammonia combustion burner 51 can be reduced.

[0128] (16) A method for operating a boiler 10 according to at least one embodiment of the present disclosure is a method for operating a boiler 10 to which ammonia fuel is supplied. The boiler 10 includes a furnace 11 including a furnace wall 101, and an ammonia combustion burner 51 having any of the configurations described above in (1) to (9) that is provided on the furnace wall 101. The ammonia fuel supplied to the first ammonia injection nozzle 521 is liquid ammonia. The ammonia combustion burner 51 is equipped with a temperature sensor 96 that detects a metal temperature. The method for operating a boiler 10 according to at least one embodiment of the present disclosure includes step S50 of calculating an injection amount of ammonia fuel to be injected from the first ammonia injection nozzle 521 based on a detection result of the temperature sensor 96, and step S60 of adjusting the injection amount so that the injection amount becomes the injection amount calculated in step S50.

[0129] According to the above configuration (16), the metal temperature of the ammonia combustion burner 51 can be suppressed, and the occurrence of burnout can be suppressed. [Explanation of symbols]

[0130] 1. Boiler system 10. Boiler 11 Furnace 20, 50 Combustion equipment 21 Burner 51 Ammonia burner (ammonia combustion burner) 51A First ammonia burner 51B Second ammonia burner 54 Combustion air nozzle 54a opening 56, 56A, 56B flame holder 57 Protrusion 101 Furnace wall 521 First ammonia injection nozzle 522 Second ammonia injection nozzle 541 Channel 542 Channel 625 Bulkhead

Claims

1. 1. An ammonia combustion burner for burning ammonia fuel in a boiler, comprising: a combustion air nozzle for ejecting combustion air; a plurality of first ammonia injection nozzles arranged at intervals in a circumferential direction inside the combustion air nozzle, the first ammonia injection nozzles being for injecting the ammonia fuel inside the combustion air nozzle; a flame stabilizer disposed downstream of the plurality of first ammonia injection nozzles; Equipped with the combustion air nozzle is configured to inject partially premixed fuel of a portion of the combustion air and the ammonia fuel injected from the plurality of first ammonia injection nozzles, and the remainder of the combustion air, a partition wall disposed downstream of the plurality of first ammonia injection nozzles and upstream of the flame stabilizer, the partition wall separating a flow path of the partially premixed fuel from a flow path of the remainder of the combustion air; an upstream opening end, at a downstream side of the plurality of first ammonia injection nozzles, for allowing the combustion air to be partially premixed with the ammonia fuel injected from the plurality of first ammonia injection nozzles to flow inside the partition wall; a downstream opening end, located upstream of an outer edge of the flame stabilizer, for allowing the partially premixed fuel, which has been partially premixed inside the partition wall, to flow out of the partition wall; Equipped with Ammonia combustion burner.

2. the combustion air nozzle has an opening for ejecting combustion air, the opening forms a gap between the opening and the outer edge of the flame stabilizer, The gap is a passage for ejecting at least a portion of the partially premixed fuel and the remainder of the combustion air from the gap.

2. The ammonia combustion burner according to claim 1.

3. The flame holder is a diffuser type flame holder.

3. The ammonia combustion burner according to claim 1 or 2.

4. at least a portion of the flame stabilizer is located within an injection range of the ammonia fuel injected by the plurality of first ammonia injection nozzles; 3. The ammonia combustion burner according to claim 1 or 2.

5. the ammonia fuel supplied to the plurality of first ammonia injection nozzles is liquid ammonia.

3. The ammonia combustion burner according to claim 1 or 2.

6. a second ammonia injection nozzle for injecting the ammonia fuel downstream of the flame stabilizer; Equipped with 3. The ammonia combustion burner according to claim 1 or 2.

7. a protrusion connected to the flame stabilizer and protruding toward the upstream side of the flame stabilizer; Equipped with 3. The ammonia combustion burner according to claim 1 or 2.

8. A temperature detection sensor for detecting the metal temperature of the combustion air nozzle Equipped with 3. The ammonia combustion burner according to claim 1 or 2.

9. an ignition detection sensor that detects ignition inside the combustion air nozzle Equipped with 3. The ammonia combustion burner according to claim 1 or 2.

10. a furnace including a furnace wall; The ammonia combustion burner according to claim 1 or 2, which is provided on the furnace wall; Equipped with Boiler.

11. a furnace including a furnace wall; The ammonia combustion burner according to claim 1 or 2, which is provided on the furnace wall; an other-fuel burner provided at a position different from the ammonia combustion burner on the furnace wall and configured to burn a fuel other than the ammonia fuel; Equipped with Boiler.

12. a furnace including a furnace wall; The ammonia combustion burner according to claim 1 or 2, which is provided on the furnace wall; an ignition detection sensor that detects ignition inside the combustion air nozzle; a control device that controls an injection amount of the ammonia fuel injected from the plurality of first ammonia injection nozzles based on a detection result of the ignition detection sensor; Equipped with The control device an injection amount calculation unit that calculates an injection amount of the ammonia fuel to be injected from the plurality of first ammonia injection nozzles based on a detection result of the ignition detection sensor; an adjustment unit that adjusts the injection amount so that the injection amount becomes the injection amount calculated by the injection amount calculation unit; have Boiler.

13. a furnace including a furnace wall; The ammonia combustion burner according to claim 1 or 2, which is provided on the furnace wall; a control device that controls an injection amount of the ammonia fuel injected from the plurality of first ammonia injection nozzles; Equipped with the ammonia fuel supplied to the plurality of first ammonia injection nozzles is liquid ammonia, the ammonia combustion burner is provided with a temperature sensor for detecting a metal temperature; The control device an injection amount calculation unit that calculates an injection amount of the ammonia fuel to be injected from the plurality of first ammonia injection nozzles based on a detection result of the temperature sensor; an adjustment unit that adjusts the injection amount so that the injection amount becomes the injection amount calculated by the injection amount calculation unit; have Boiler.

14. 1. A method for operating a boiler supplied with ammonia fuel, comprising: The boiler comprises: a furnace including a furnace wall; The ammonia combustion burner according to claim 1 or 2, which is provided on the furnace wall; an ignition detection sensor that detects ignition inside the combustion air nozzle; Including, calculating an injection amount of the ammonia fuel to be injected from the plurality of first ammonia injection nozzles based on a detection result of the ignition detection sensor; adjusting the injection amount to the injection amount calculated in the calculating step; Equipped with How to operate a boiler.

15. 1. A method for operating a boiler supplied with ammonia fuel, comprising: The boiler comprises: a furnace including a furnace wall; The ammonia combustion burner according to claim 1 or 2, which is provided on the furnace wall; Including, the ammonia fuel supplied to the plurality of first ammonia injection nozzles is liquid ammonia, the ammonia combustion burner is provided with a temperature sensor for detecting a metal temperature; calculating an injection amount of the ammonia fuel to be injected from the plurality of first ammonia injection nozzles based on a detection result of the temperature sensor; adjusting the injection amount to the injection amount calculated in the calculating step; Equipped with How to operate a boiler.

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