Boiler, method for modifying boiler, and method for operating boiler

Abstract

To provide a boiler that can strike a balance between securing an amount of ammonia supply and ignition stability, and to provide a method for modifying a boiler and a method for operating a boiler.SOLUTION: A boiler includes: a furnace for combusting fuel; an ammonia diffusion burner configured to jet liquid ammonia into the furnace; and an ammonia premixing burner configured to jet a pre-mixed gas of a gaseous ammonia and air into the furnace.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to a boiler, a method for retrofitting a boiler, and a method for operating a boiler. [Background technology]

[0002] Boilers equipped with burners that burn ammonia as fuel are known.

[0003] Patent Document 1 describes a boiler equipped with a burner that burns ammonia and pulverized coal. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2023-39881 A Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, in order to ensure the amount of ammonia supplied while suppressing the increase in size of fuel piping, etc., it is more advantageous to supply liquid ammonia to the furnace and perform diffusion combustion, compared to supplying gaseous ammonia to the furnace. On the other hand, ammonia has a slower combustion speed than general hydrocarbon fuels such as methane, and has the property of being difficult to ignite and burn. Furthermore, since liquid ammonia has a large heat of vaporization, it is thought that its ignition ability is reduced. Therefore, in a boiler that uses ammonia as fuel, it is desirable to be able to ensure both the amount of ammonia supplied and ignition stability.

[0006] In view of the above circumstances, at least one embodiment of the present invention has an object to provide a boiler, a boiler modification method, and a boiler operation method that can ensure both an ammonia supply amount and ignition stability. [Means for solving the problem]

[0007] At least one embodiment of the boiler of the present invention comprises: a furnace for burning fuel; an ammonia diffusion burner configured to inject liquid ammonia into the furnace; an ammonia premix burner configured to inject a premix of gaseous ammonia and air into the furnace; Equipped with.

[0008] Further, a method for retrofitting a boiler according to at least one embodiment of the present invention includes the steps of: A method for retrofitting a boiler including a furnace, an oil burner for injecting oil into the furnace, and a pulverized fuel burner for injecting pulverized fuel together with air into the furnace, comprising: converting the oil burner into an ammonia diffusion burner for injecting liquid ammonia into the furnace; converting the pulverized fuel burner into an ammonia premix burner for injecting a premix of gaseous ammonia and air into the furnace; Equipped with.

[0009] Further, a method for retrofitting a boiler according to at least one embodiment of the present invention includes the steps of: A method for retrofitting a boiler including a furnace, an oil burner for injecting oil into the furnace, and a pulverized fuel burner for injecting pulverized fuel together with air into the furnace, comprising: converting the oil burner into an ammonia premix burner for injecting a premix of gaseous ammonia and air into the furnace; converting the pulverized fuel burner into an ammonia diffusion burner for injecting liquid ammonia into the furnace; Equipped with.

[0010] Further, a method for operating a boiler according to at least one embodiment of the present invention includes the steps of: A method for operating the boiler described above, comprising: The method includes a step of adjusting a diffusion ammonia supply amount, which is an ammonia supply amount to the furnace via the ammonia diffusion burner, and a premixed ammonia supply amount, which is an ammonia supply amount to the furnace via the ammonia premixing burner, based on a required load of the boiler; In the step, when the load of the boiler is reduced, the diffused ammonia supply amount is reduced in preference to the premixed ammonia supply amount. Effect of the Invention

[0011] According to at least one embodiment of the present invention, there are provided a boiler, a boiler modification method, and a boiler operation method that can ensure both an ammonia supply amount and ignition stability. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a schematic configuration diagram showing a boiler according to an embodiment. [Diagram 2] FIG. 2 is a schematic diagram of a burner applicable to the boiler shown in FIG. [Diagram 3] FIG. 1 is a schematic diagram illustrating a portion of a boiler according to an embodiment. [Figure 4] FIG. 1 is a schematic diagram illustrating a portion of a boiler according to an embodiment. [Diagram 5] FIG. 1 is a schematic diagram illustrating a portion of a boiler according to an embodiment. [Figure 6] 1 is a graph showing an example of the change over time in the boiler load and the proportion of the supply amount, on a calorific value basis, of fuel (ammonia or pulverized fuel) supplied to each burner when carrying out a boiler operation method according to one embodiment. [Figure 7] 1 is a graph showing an example of the change over time in the boiler load and the proportion of the supply amount, on a calorific value basis, of fuel (ammonia or pulverized fuel) supplied to each burner when carrying out a boiler operation method according to one embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, some embodiments of the present invention will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative positions, etc. of the components described as the embodiments or shown in the drawings are not intended to limit the scope of the present invention, but are merely illustrative examples. In the following description, top and upper refer to the upper side in the vertical direction, and bottom and lower refer to the lower side in the vertical direction, and the vertical direction is not precise and includes errors.

[0014] (Boiler and burner configuration) FIG. 1 is a schematic configuration diagram showing a boiler according to one embodiment.

[0015] As shown in Fig. 1, a boiler 10 according to one embodiment is a boiler that can generate superheated steam by burning pulverized fuel made by pulverizing solid fuel with a burner and exchanging the heat generated by the combustion with feed water or steam. Biomass fuel, coal, etc. are used as the solid fuel.

[0016] The boiler 10 has a furnace 11, a combustion device 20, and a combustion gas passage 12. The furnace 11 has a hollow rectangular cylinder shape and is installed vertically. The furnace wall 101 constituting the inner wall surface of the furnace 11 is composed of a plurality of heat transfer tubes and fins connecting the heat transfer tubes, and recovers heat generated by the combustion of pulverized fuel by heat exchange with water and steam flowing inside the heat transfer tubes, while suppressing the temperature rise of the furnace wall 101.

[0017] The combustion device 20 is installed in the lower region of the furnace 11. In this embodiment, the combustion device 20 has a plurality of burners 21A, 21B, 21C, 21D, 21E, and 21F (hereinafter, they may be collectively referred to as "burners 21") attached to the furnace wall 101. The burners 21 may be arranged in a plurality of stages along the vertical direction, with each set being 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). Note that, for convenience of illustration, only two burners of one set are shown in FIG. 1, and each set is denoted by the reference numerals 21A, 21B, 21C, 21D, 21E, and 21F. The shape of the furnace, the number of burner stages, the number of burners in one stage, the arrangement of the burners, and the like are not limited to this embodiment.

[0018] For example, the combustion device 20 may be a swirl combustion type combustion device in which, as described above, a plurality of burners 21 are evenly arranged along the circumferential direction of the furnace 11 and configured to eject fuel along the circumferential direction around a center line extending in the vertical direction of the furnace 11.

[0019] The burners 21A, 21B, 21C, 21D, 21E, and 21F are connected to a plurality of mills (pulverizers) 31A, 31B, 31C, 31D, 31E, and 31F (hereinafter, sometimes collectively referred to as "mills 31") via a plurality of pulverized fuel supply pipes 22A, 22B, 22C, 22D, 22E, and 22F (hereinafter, sometimes collectively referred to as "pulverized fuel supply pipes 22"). The mill 31 is, for example, a vertical roller mill in which a pulverizing table (not shown) is supported inside so as to be rotatable and a plurality of pulverizing rollers (not shown) are 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 (transport gas, oxidizing gas) supplied to the mill 31. In the classifier, the fuel particles are classified into pulverized fuel having a particle size equal to or smaller than that suitable for combustion in the burner 21, and coarse pulverized fuel having a particle size larger than that. The pulverized fuel passes through the classifier and is supplied to the burner 21 together with primary air via the pulverized fuel supply pipe 22. The coarse pulverized fuel that does not pass through the classifier falls onto the grinding table by its own weight inside the mill 31 and is re-ground.

[0020] An air register 23 is provided on the outside of the furnace 11 at the mounting position of the burner 21, and one end of an air duct 24 is connected to the air register 23. A forced draft fan (FDF: 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 installed in the air duct 24 (details will be described later), and is supplied to the burner 21 via the air register 23 as secondary air (combustion air, oxidizing gas), and is introduced into the furnace 11.

[0021] 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 feed water or steam flowing inside each heat exchanger. The arrangement and shape of each heat exchanger are not limited to the form shown in FIG. 1.

[0022] A flue 13 is connected to the downstream side of the combustion gas passage 12, and discharges the combustion gas whose heat has been recovered by the heat exchanger. An air preheater (air heater) 42 is provided between the flue 13 and the air duct 24, and heat is exchanged between the air flowing through the air duct 24 and the combustion gas flowing through the flue 13, thereby heating the primary air supplied to the mill 31 and the secondary air supplied to the burner 21, thereby recovering further heat from the combustion gas after heat exchange with water and steam.

[0023] Further, 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 having an effect of reducing nitrogen oxides, such as ammonia and urea water, to the combustion gas flowing in the flue 13, and promotes a reaction between the nitrogen oxides (NOx) in the combustion gas to which the reducing agent is supplied and the reducing agent by the catalytic action of a denitration catalyst provided in the denitration device 43, thereby removing and reducing the nitrogen oxides in the combustion gas. A gas duct 41 is connected to the flue 13 downstream of the air preheater 42. The gas duct 41 is provided with environmental devices, such as a dust collector 44 such as an electric dust collector that removes ash and the like in the combustion gas, and a desulfurization device 46 that removes sulfur oxides, as well as an induced draft fan (IDF) 45 for directing the exhaust gas to these environmental devices. The downstream end of the gas duct 41 is connected to a chimney 47, through which the combustion gas treated in the environmental device is discharged to the outside of the system as exhaust gas.

[0024] In the boiler 10, when the multiple mills 31 are driven, the pulverized and classified pulverized fuel is supplied to the burner 21 together with the primary air through the pulverized fuel supply pipe 22. In addition, secondary air heated by the air preheater 42 is supplied to the burner 21 through the wind duct 24 and the wind box 23. The burner 21 blows a pulverized fuel mixture, which is a mixture of the pulverized fuel and the primary air, into the furnace 11, and also blows secondary air into the furnace 11. The pulverized fuel mixture blown into the furnace 11 ignites and reacts with the secondary air to form a flame. A flame is formed in the lower region of the furnace 11, and the high-temperature combustion gas rises inside the furnace 11 and flows into the combustion gas passage 12. In this embodiment, air is used as the oxidizing gas (primary air, secondary air), but the oxidizing gas may have a higher or lower oxygen ratio than air, and stable combustion in the furnace 11 is achieved by adjusting the ratio of the amount of oxygen to the amount of fuel supplied to an appropriate range.

[0025] The combustion gas flowing into the combustion gas passage 12 exchanges heat with water and steam in a superheater 102, a reheater 103, and a coal 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 combustion gas exchanges heat with primary air and secondary air in an air preheater 42, and is then discharged into a 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 combustion 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 devices from the flue 13 to the gas duct 41 with respect to the combustion gas flow does not necessarily have to be in the order described above.

[0026] In the above-described embodiment, the boiler of the present invention has been described as a boiler that uses solid fuel as fuel. The solid fuel used in the boiler may be coal, biomass fuel, petroleum coke (PC) fuel, petroleum residue, or the like.

[0027] The fuel for the boiler is not limited to solid fuels, and can also be petroleum such as heavy oil, light oil, and heavy oil, industrial wastewater, liquid ammonia, etc. Also, gaseous fuels such as natural gas, various petroleum gases, by-product gases generated in the steelmaking process, hydrogen gas, and ammonia gas can also be used.

[0028] Furthermore, the present invention can be applied to a multi-fuel boiler that uses a combination of these various fuels.

[0029] The boiler 10, according to some embodiments, is configured to combust at least ammonia.

[0030] Fig. 2 is a schematic diagram of a burner 21' applicable to the boiler 10 shown in Fig. 1. The burner 21 according to some embodiments can be obtained by modifying the burner 21' described below.

[0031] 2, the burner 21' (corresponding to each of the burners 21A to 21F described above) includes a central burner 60 located in the vertical center, and pulverized fuel burners 50A, 50B (hereinafter collectively referred to as pulverized fuel burners 50) located above and below the central burner 60. In addition, combustion air nozzles 56 are provided above and below these burner groups (the central burner 60 and the pulverized fuel burners 50A, 50B).

[0032] The pulverized fuel burner 50 includes a pulverized fuel nozzle 52 and an air nozzle 54. The pulverized fuel nozzle 52 is adapted to blow primary air supplied from the pulverized fuel supply pipe 22 and pulverized fuel (such as pulverized coal) carried by the primary air into the furnace 11. The air nozzle 54 is adapted to blow secondary air (heated air heated by the air heater 42) supplied from the air duct 24 into the furnace 11.

[0033] The central burner 60 is configured to inject fuel for diffusion combustion together with air into the furnace 11. In the example shown in Fig. 2, the central burner 60 includes an oil nozzle 62 configured to inject oil fuel into the furnace 11, and an air nozzle 66 provided to surround the periphery of the oil nozzle 62. The air nozzle 66 may be configured to inject secondary air (heated air heated by the air heater 42) supplied from the air duct 24 into the furnace 11.

[0034] The combustion air nozzle 56 may be configured to blow secondary air (heated air heated by the air heater 42 ) supplied from the air duct 24 into the furnace 11 .

[0035] Next, the boiler and burner according to some embodiments will be described in more detail. Each of Fig. 3 to Fig. 5 is a schematic diagram showing a part of a boiler according to one embodiment.

[0036] The burner 21 of the boiler 10 according to the embodiment shown in Fig. 3 to Fig. 5 includes an ammonia diffusion burner 70 for injecting liquid ammonia into the furnace 11, and an ammonia premixing burner 72 for injecting a premixed gas of gaseous ammonia and air into the furnace 11. As shown in the drawings, the ammonia diffusion burner 70 and the ammonia premixing burner 72 may be provided adjacent to each other.

[0037] 3 to 5, the burner 21 includes a pulverized fuel burner 50 for injecting pulverized fuel (such as pulverized coal) together with air into the furnace 11. As shown in the drawings, the pulverized fuel burner 50 may be provided adjacent to either the ammonia diffusion burner 70 or the ammonia premix burner 72.

[0038] In the exemplary embodiment shown in Figures 3 and 4, the burner 21 includes an ammonia diffusion burner 70 obtained by modifying the central burner 60 and an ammonia premix burner 72 obtained by modifying the pulverized fuel burner 50B.

[0039] That is, the burner 21 shown in Figures 3 and 4 can be obtained by modifying the oil burner (central burner 60) including the oil nozzle 62 in the burner 21' shown in Figure 2 into an ammonia diffusion burner 70, and by modifying the pulverized fuel burner 50B (the pulverized fuel burner adjacent to the oil burner) in the burner 21' shown in Figure 2 into an ammonia premixed burner 72.

[0040] The oil burner (central burner 60) including the oil nozzle 62 in the burner 21' shown in Figure 2 may be modified to an ammonia diffusion burner 70 by replacing the oil nozzle 62 of the burner 21' with a liquid ammonia nozzle 74 (see Figures 3 and 4) for spraying liquid ammonia into the furnace 11.

[0041] The pulverized fuel burner 50B in the burner 21' shown in FIG. 2 may be modified to the ammonia premixed burner 72 by providing the pulverized fuel burner 50B in the burner 21' with a premixed gas forming section 82 (see FIGS. 3 and 4) for forming a premixed gas of ammonia and air.

[0042] In the exemplary embodiment shown in Fig. 3, the premixed gas forming section 82 includes a premixed gas pipe 84 connected to the pulverized fuel supply pipe 22 and supplied with high-temperature (e.g., 200°C or higher) heated air (e.g., secondary air from the air duct 24), and a liquid ammonia nozzle 86 for injecting liquid ammonia into the premixed gas pipe 84. The liquid ammonia injected into the heated air flow of the premixed gas pipe 84 is vaporized by the high-temperature heated air and mixed with the heated air to form a premixed gas. The premixed gas thus formed is supplied to the pulverized fuel nozzle 52 of the ammonia premixed burner 72 via the pulverized fuel supply pipe 22 and is injected from the pulverized fuel nozzle 52 into the furnace 11.

[0043] The pulverized fuel supply pipe 22 may be provided with a gate valve 92 for switching between a supply state and a non-supply state of the pulverized fuel and primary air from the pulverized fuel supply pipe 22 to the furnace 11. The premixing pipe 84 may be provided with a gate valve 94 for switching between a supply state and a non-supply state of the premixed gas from the premixing pipe 84 to the pulverized fuel supply pipe 22.

[0044] In the exemplary embodiment shown in FIG. 4, the premixed gas forming section 82 includes the pulverized fuel supply pipe 22 and a gaseous ammonia supply pipe 110 connected to the pulverized fuel supply pipe 22 for supplying gaseous ammonia to the pulverized fuel supply pipe 22. The gaseous ammonia supply pipe 110 may be provided with a gate valve 112 for switching between a supply state and a non-supply state of gaseous ammonia from the gaseous ammonia supply pipe 110 to the pulverized fuel supply pipe 22. The gaseous ammonia supplied from the gaseous ammonia supply pipe 110 to the pulverized fuel supply pipe 22 is mixed with the primary air flowing through the pulverized fuel supply pipe 22 together with the pulverized fuel to form a premixed gas. The premixed gas thus formed is supplied to the pulverized fuel nozzle 52 of the ammonia premixed burner 72 via the pulverized fuel supply pipe 22 and ejected from the pulverized fuel nozzle 52 into the furnace 11.

[0045] In the exemplary embodiment shown in FIG. 5, the burner 21 includes an ammonia diffusion burner 70 obtained by modifying the pulverized fuel burner 50B and an ammonia premix burner 72 obtained by modifying the central burner 60.

[0046] That is, the burner 21 shown in FIG. 5 can be obtained by modifying the oil burner (central burner 60) including the oil nozzle 62 in the burner 21' shown in FIG. 2 into an ammonia premixed burner 72, and by modifying the pulverized fuel burner 50B (the pulverized fuel burner adjacent to the oil burner) in the burner 21' shown in FIG. 2 into an ammonia diffusion burner 70.

[0047] The oil burner (central burner 60) including the oil nozzle 62 in the burner 21' shown in Fig. 2 may be modified to the ammonia premixed burner 72 by removing the oil nozzle 62 from the burner 21', installing a gaseous ammonia nozzle 120 for ejecting gaseous ammonia in the space formed by removing the oil nozzle 62, and forming a heated air passage 118 through which heated air (secondary air from the air duct 24, etc.) flows around the gaseous ammonia nozzle 120. The gaseous ammonia ejected from the gaseous ammonia nozzle 120 is mixed with the heated air flowing through the heated air passage 118 to form a premixed gas, and the premixed gas is ejected into the furnace 11.

[0048] The conversion of the pulverized fuel burner 50B in the burner 21' shown in FIG. 2 to an ammonia diffusion burner 70 may be accomplished by replacing the pulverized fuel burner 50B in the burner 21' with a diffusion burner including a liquid ammonia nozzle 74 and an air nozzle 116.

[0049] 3 to 5, liquid ammonia from a liquid ammonia storage section 76 is supplied to the ammonia diffusion burner 70 via an ammonia line 78. The ammonia line 78 may be provided with a first valve 80 capable of adjusting the amount of ammonia supplied to the ammonia diffusion burner 70.

[0050] 3 to 5, a premixed gas of ammonia and air formed from liquid ammonia supplied from a liquid ammonia storage unit 76 via an ammonia line 88 is supplied to the ammonia premixed burner 72. The ammonia line 88 may be provided with a second valve 90 capable of adjusting the amount of ammonia supplied to the ammonia premixed burner 72.

[0051] In the exemplary embodiment shown in FIG. 3, the liquid ammonia from the liquid ammonia reservoir 76 is supplied in a liquid state to the liquid ammonia nozzle 86 (premixed gas formation section 82) via an ammonia line 88.

[0052] In the exemplary embodiment shown in FIG. 4 and FIG. 5, liquid ammonia from the liquid ammonia storage section 76 is vaporized in a vaporizer 114 and then supplied to the gaseous ammonia supply pipe 110 (premixed gas formation section 82) or the gaseous ammonia nozzle 120 via an ammonia line 88.

[0053] As shown in Figures 3 to 5, the pulverized fuel burner 50A is supplied with pulverized fuel from a pulverized fuel reservoir 96 via a pulverized fuel line 98 and a pulverized fuel supply pipe 22. The pulverized fuel line 98 may be provided with a pulverized fuel valve 99 for adjusting the amount of pulverized fuel supplied to the pulverized fuel burner 50A.

[0054] 3 to 5, the boiler 10 may include a control device 200 (control unit) for adjusting the amount of ammonia supplied to the ammonia diffusion burner 70 via the ammonia line 78, the amount of ammonia supplied to the ammonia premix burner 72 via the ammonia line 88, and / or the amount of pulverized fuel supplied to the pulverized fuel burner 50A via the pulverized fuel line 98. The control device 200 may be configured to adjust the opening of the first valve 80, the second valve 90, and / or the pulverized fuel valve 99 so that the amount of each fuel supplied becomes a predetermined value.

[0055] The control device 200 may include a computer equipped with a processor (CPU, etc.), a main storage device (memory device; RAM, etc.), an auxiliary storage device, an interface, etc. The control device 200 may receive target values ​​of the amount of ammonia supplied to the ammonia diffusion burner 70 via the ammonia line 78, the amount of ammonia supplied to the ammonia premix burner 72 via the ammonia line 88, and / or the amount of pulverized fuel supplied to the pulverized fuel burner 50A via the pulverized fuel line 98 from a higher-level control device, etc. The control device 200 may be configured to adjust the opening degree of the first valve 80, the second valve 90, and / or the pulverized fuel valve 99 so that each supply amount approaches the target value. Alternatively, the control device 200 may be configured to receive a required load of the boiler 10 from a higher-level control device, etc. The control device 200 may be configured to adjust the opening degree of the first valve 80, the second valve 90, and / or the pulverized fuel valve 99 so as to satisfy the required load.

[0056] In the boiler 10 according to the embodiment described above, the ammonia diffusion burner 70 ejects ammonia in liquid form into the furnace 11, so that the amount of ammonia supply can be increased while suppressing the increase in size of the fuel piping and the like. In addition, the ammonia premixing burner 72 having relatively good ignition properties is provided together with the ammonia diffusion burner 70, so that the deterioration of ignition properties and combustibility caused by using the ammonia diffusion burner 70 that ejects liquid ammonia can be suppressed. Therefore, according to the embodiment described above, it is possible to ensure both the amount of ammonia supply and ignition stability. In addition, by providing the ammonia premixing burner 72 at a position adjacent to the ammonia diffusion burner 70, the deterioration of ignition properties and combustibility caused by using the ammonia diffusion burner 70 that ejects liquid ammonia can be more effectively suppressed.

[0057] In addition, in the boiler 10 according to the above embodiment, in addition to the ammonia diffusion burner 70 and the ammonia premixed burner 72, the pulverized fuel burner 50A having relatively good ignitability is provided, so that the deterioration of ignitability and combustibility caused by using the ammonia diffusion burner 70 that spouts liquid ammonia can be more effectively suppressed. In addition, by providing the pulverized fuel burner 50A at a position adjacent to either the ammonia diffusion burner 70 or the ammonia premixed burner 72, the deterioration of ignitability and combustibility caused by using the ammonia diffusion burner 70 that spouts liquid ammonia can be more effectively suppressed. In the exemplary embodiment shown in FIG. 3 and FIG. 4, the pulverized fuel burner 50A is provided adjacent to the ammonia diffusion burner 70. In the exemplary embodiment shown in FIG. 5, the pulverized fuel burner 50A is provided adjacent to the ammonia premixed burner 72.

[0058] Next, a description will be given of a method for operating the above-mentioned boiler 10 according to some embodiments. The operation method described below can be performed using the above-mentioned control device 200 or manually.

[0059] 6 and 7 are graphs showing an example of the time change of the boiler load and the ratio of the heat input of the ammonia diffusion burner 70, the ammonia premixing burner 72, and the pulverized fuel burner 50A (i.e., the ratio of the supply amount of the fuel (ammonia (NH3) or pulverized fuel) supplied to each burner on a calorific value basis) when carrying out the boiler operation method according to one embodiment. In the graphs of FIG. 6 and FIG. 7, the boiler load is gradually reduced from 100% (rated load) to 25%.

[0060] In the operation method of the boiler 10 according to some embodiments, the diffusion ammonia feed rate, which is the amount of ammonia fed to the furnace 11 via the ammonia diffusion burner 70, and the premixed ammonia feed rate, which is the amount of ammonia fed to the furnace 11 via the ammonia premixed burner 72, are adjusted based on the required load of the boiler 10. Here, when the load of the boiler 10 is reduced based on the required load, the diffusion ammonia feed rate is reduced in preference to the premixed ammonia feed rate. That is, in this embodiment, when the load of the boiler 10 is reduced, first, the diffusion ammonia feed rate is reduced while maintaining the premixed ammonia feed rate, and then, when the diffusion ammonia feed rate approaches zero, the premixed ammonia feed rate is reduced, as shown in Figs. 6 and 7.

[0061] In the above-described operating method, when the load of the boiler 10 is reduced, the amount of diffused ammonia supplied to the ammonia diffusion burner 70, which has a relatively low ignition property, is reduced in priority to the amount of premixed ammonia supplied to the ammonia premixed burner 72, which has a relatively good ignition property, so that the load of the boiler 10 can be reduced while maintaining ignition stability.

[0062] In one embodiment, when the load of the boiler 10 is reduced based on the required load, the diffusion ammonia supply amount is reduced in preference to the premixed ammonia supply amount, and the premixed ammonia supply amount is reduced in preference to the pulverized fuel supply amount. That is, in this embodiment, when the load of the boiler 10 is reduced, as shown in Fig. 6, first, the diffusion ammonia supply amount is reduced while maintaining the premixed ammonia supply amount and the pulverized fuel supply amount, and then, when the diffusion ammonia supply amount approaches zero, the premixed ammonia supply amount is reduced while maintaining the pulverized fuel, and further, when the premixed ammonia supply amount approaches zero, the pulverized fuel supply amount is reduced.

[0063] According to the above-described embodiment, when the load of the boiler 10 is reduced, the amount of diffusion ammonia supplied to the ammonia diffusion burner having relatively low ignition property is reduced in preference to the amount of premixed ammonia supplied to the ammonia premixed burner having relatively good ignition property, and the amount of premixed ammonia supplied to the ammonia premixed burner is reduced in preference to the amount of pulverized fuel supplied to the pulverized fuel burner having better ignition property. This makes it possible to further reduce the load of the boiler while maintaining ignition stability.

[0064] In one embodiment, when the load of the boiler 10 is reduced based on the required load, the diffusion ammonia supply amount is reduced in preference to the premixed ammonia supply amount while maintaining the ammonia co-firing ratio. Here, the ammonia co-firing ratio is the ratio of the sum of the diffusion ammonia supply amount and the premixed ammonia supply amount to the total of the diffusion ammonia supply amount, the premixed ammonia supply amount, and the pulverized fuel supply amount on a calorific value basis. That is, in this embodiment, when the load of the boiler 10 is reduced, as shown in FIG. 7, both the ammonia supply amount and the pulverized fuel supply amount are reduced while maintaining the ratio of the ammonia supply amount (the sum of the diffusion ammonia supply amount and the premixed ammonia supply amount) to the pulverized fuel supply amount constant. In addition, as for the ammonia supply amount, first, the diffusion ammonia supply amount is reduced while maintaining the premixed ammonia supply amount, and then, when the diffusion ammonia supply amount approaches zero, the premixed ammonia supply amount is reduced.

[0065] According to the above-described embodiment, when the load of the boiler 10 is reduced, the amount of diffused ammonia supplied to the ammonia diffusion burner 70, which has a relatively low ignition property, is reduced in preference to the amount of premixed ammonia supplied to the ammonia premixed burner 72, which has a relatively good ignition property, while maintaining the ammonia co-firing ratio. Therefore, the load of the boiler 10 can be reduced while maintaining ignition stability, while increasing the amount of ammonia input to the boiler 10 as much as possible.

[0066] The contents described in each of the above embodiments can be understood, for example, as follows.

[0067] [1] At least one embodiment of the boiler (10) of the present invention comprises: a furnace (11) for burning fuel; an ammonia diffusion burner (70) configured to inject liquid ammonia into the furnace; an ammonia premix burner (72) configured to inject a premix of gaseous ammonia and air into the furnace; Equipped with.

[0068] In the configuration of [1] above, the ammonia diffusion burner ejects ammonia in liquid form into the furnace, so that the amount of ammonia supply can be increased while suppressing the increase in size of the fuel piping, etc. In addition, an ammonia premixed burner with relatively good ignition properties is provided together with the ammonia diffusion burner, so that the deterioration of ignition properties and combustibility caused by using the ammonia diffusion burner that ejects liquid ammonia can be suppressed. Therefore, according to the configuration of [1] above, it is possible to ensure both the amount of ammonia supply and ignition stability.

[0069] [2] In some embodiments, in the configuration of [1] above, The boiler comprises: The apparatus further includes a pulverized fuel burner (50A) configured to inject pulverized fuel together with air into the furnace.

[0070] According to the above-mentioned configuration [2], since the pulverized fuel burner having relatively good ignition performance is provided in addition to the ammonia diffusion burner and the ammonia premixed burner, it is possible to more effectively suppress the deterioration of ignition performance and combustibility caused by the use of the ammonia diffusion burner that ejects liquid ammonia. Therefore, according to the above-mentioned configuration [2], it is possible to secure the ammonia supply amount and achieve ignition stability at the same time.

[0071] [3] In some embodiments, in the configuration of [1] or [2] above, The boiler comprises: A control unit (e.g., a control device 200) configured to adjust a diffusion ammonia supply amount, which is an ammonia supply amount to the furnace via the ammonia diffusion burner, and a premixed ammonia supply amount, which is an ammonia supply amount to the furnace via the ammonia premixed burner, based on a required load of the boiler; The control unit is configured to reduce the diffused ammonia supply rate in preference to the premixed ammonia supply rate when reducing a load on the boiler.

[0072] According to the configuration [3] above, when the load on the boiler is reduced, the amount of diffused ammonia supplied to the ammonia diffusion burner, which has relatively low ignition property, is reduced in priority to the amount of premixed ammonia supplied to the ammonia premixed burner, which has relatively good ignition property. This makes it possible to reduce the load on the boiler while maintaining ignition stability.

[0073] [4] In some embodiments, in the configuration of [3] above, The boiler comprises: A pulverized fuel burner configured to inject pulverized fuel together with air into the furnace; The control unit is configured to adjust a pulverized fuel supply amount to the furnace via the pulverized fuel burner in addition to the diffusion ammonia supply amount and the premixed ammonia supply amount; The control unit is configured to reduce the diffusion ammonia supply amount in preference to the premixed ammonia supply amount and to reduce the premixed ammonia supply amount in preference to the pulverized fuel supply amount when reducing a load on the boiler.

[0074] According to the configuration [4] above, when the load on the boiler is reduced, the amount of diffusion ammonia supplied to the ammonia diffusion burner having relatively low ignition property is reduced in preference to the amount of premixed ammonia supplied to the ammonia premixed burner having relatively good ignition property, and the amount of premixed ammonia supplied to the ammonia premixed burner is reduced in preference to the amount of pulverized fuel supplied to the pulverized fuel burner having better ignition property. This makes it possible to further reduce the load on the boiler while maintaining ignition stability.

[0075] [5] In some embodiments, in the configuration of [3] above, The boiler comprises: A pulverized fuel burner configured to inject pulverized fuel together with air into the furnace; The control unit is configured to adjust a pulverized fuel supply amount to the furnace via the pulverized fuel burner in addition to the diffusion ammonia supply amount and the premixed ammonia supply amount; The control unit is configured to reduce the diffused ammonia supply amount in preference to the premixed ammonia supply amount while maintaining an ammonia co-firing ratio when reducing a load of the boiler, The ammonia co-firing ratio is a ratio on a calorific value basis of the sum of the diffusion ammonia supply amount and the premixed ammonia supply amount to the total of the diffusion ammonia supply amount, the premixed ammonia supply amount, and the pulverized fuel supply amount.

[0076] According to the configuration [5] above, when the load on the boiler is reduced, the amount of diffused ammonia supplied to the ammonia diffusion burner, which has relatively low ignition property, is reduced in priority to the amount of premixed ammonia supplied to the ammonia premixed burner, which has relatively good ignition property, while maintaining the ammonia co-firing ratio. Therefore, the load on the boiler can be reduced while maintaining ignition stability, while increasing the amount of ammonia input to the boiler as much as possible.

[0077] [6] At least one embodiment of the present invention relates to a method for retrofitting a boiler, comprising: A method for retrofitting a boiler including a furnace (11), an oil burner (e.g., a central burner 60) for injecting oil into the furnace, and a pulverized fuel burner (50B) for injecting pulverized fuel together with air into the furnace, comprising: converting the oil burner into an ammonia diffusion burner (70) for injecting liquid ammonia into the furnace; converting the pulverized fuel burner (72) into an ammonia premix burner (72) for injecting a premix of gaseous ammonia and air into the furnace; Equipped with.

[0078] According to the method of [6] above, the oil burner is modified to an ammonia diffusion burner and the pulverized fuel burner is modified to an ammonia premix burner, thereby obtaining a boiler having the configuration of [1] above. The boiler obtained in this way can ensure both the ammonia supply amount and ignition stability.

[0079] [7] In some embodiments, in the method of [6] above, In the step of modifying the oil burner, an oil nozzle of the oil burner is replaced with a liquid ammonia nozzle (74) for spraying liquid ammonia into the furnace; In the step of modifying the pulverized fuel burner, a premixed gas forming section (82) for forming a premixed gas of gaseous ammonia and air is provided in the pulverized fuel burner.

[0080] According to the method of [7] above, by replacing the oil nozzle of the oil burner with an ammonia nozzle and installing a premixed gas generator in the pulverized fuel burner, a boiler having the configuration of [1] above can be obtained relatively easily.

[0081] [8] A method for retrofitting a boiler according to at least one embodiment of the present invention includes: A method for retrofitting a boiler including a furnace (11), an oil burner (e.g., a central burner 60) for injecting oil into the furnace, and a pulverized fuel burner (50B) for injecting pulverized fuel together with air into the furnace, comprising: converting the oil burner into an ammonia premix burner (72) for injecting a premix of gaseous ammonia and air into the furnace; converting the pulverized fuel burner into an ammonia diffusion burner (70) for injecting liquid ammonia into the furnace; Equipped with.

[0082] According to the method of [8] above, the oil burner is modified to an ammonia premix burner and the pulverized fuel burner is modified to an ammonia diffusion burner, thereby obtaining a boiler having the configuration of [1] above. The boiler obtained in this way can ensure both the ammonia supply amount and ignition stability.

[0083] [9] At least one embodiment of the present invention relates to a method for operating a boiler, comprising: A method for operating a boiler according to any one of the above [1] to [5], The method includes a step of adjusting a diffusion ammonia supply amount, which is an ammonia supply amount to the furnace via the ammonia diffusion burner, and a premixed ammonia supply amount, which is an ammonia supply amount to the furnace via the ammonia premixing burner, based on a required load of the boiler; In the step, when the load of the boiler is reduced, the diffused ammonia supply amount is reduced in preference to the premixed ammonia supply amount.

[0084] According to the method of [9] above, when the load on the boiler is reduced, the amount of diffused ammonia supplied to the ammonia diffusion burner, which has a relatively low ignition property, is reduced in priority to the amount of premixed ammonia supplied to the ammonia premixed burner, which has a relatively good ignition property, so that the load on the boiler can be reduced while maintaining ignition stability.

[0085] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and also includes modifications to the above-described embodiments and appropriate combinations of these modifications.

[0086] In this specification, expressions expressing relative or absolute configuration, such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial," do not only strictly represent such a configuration, but also represent 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 indicating that things are in an equal state, such as "identical," "equal," and "homogeneous," 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. Furthermore, in this specification, expressions describing shapes such as a rectangular shape or a cylindrical shape do not only refer to shapes such as a rectangular shape or a cylindrical shape in the strict geometric sense, but also refer to shapes that include uneven portions, chamfered portions, etc., to the extent that the same effect can be obtained. In addition, in this specification, the expressions "comprise," "include," or "have" a certain component are not exclusive expressions that exclude the presence of other components. [Explanation of symbols]

[0087] 10. Boiler 11 Furnace 12 Combustion gas passage 13 Flue 20 Combustion equipment 21(21A-21F) Burner 22(22A-22F) Fine fuel supply pipe 23 Wind box 24 Air duct 31 Mil 32 Forced draft fan 41 Gas Duct 42 Air preheater (air heater) 43 Denitration equipment 44 Equipment 46 Desulfurization equipment 47 Chimney 50 Pulverized fuel burner 50A pulverized fuel burner 50B Pulverized Fuel Burner 52 Pulverized fuel nozzle 54 Air nozzle 56 Combustion air nozzle 60 Central Burner 62 Oil nozzle 66 Air Nozzle 70 Ammonia diffusion burner 72 Ammonia premix burner 74 Liquid Ammonia Nozzle 76 Liquid ammonia storage section 78 Ammonia Line 80 First valve 82 Premixed air-fuel formation section 84 Premixed Air Pipe 86 Liquid Ammonia Nozzle 88 Ammonia Line 90 Second valve 92 Gate valve 94 Gate valve 96 Pulverized fuel storage section 98 Pulverized Fuel Line 99 Pulverized Fuel Valve 101 Furnace wall 102 Superheater 102A superheater 102B Superheater 102C superheater 103 Reheater 103A Reheater 103B Reheater 104 Economizer 110 Gaseous ammonia supply pipe 112 Gate valve 114 Carburetor 116 Air Nozzle 118 Heated air passage 120 Gaseous ammonia nozzle 200 Control device

Claims

1. a furnace for burning fuel; an ammonia diffusion burner configured to inject liquid ammonia into the furnace; an ammonia premix burner configured to inject a premix of gaseous ammonia and air into the furnace; A boiler equipped with

2. The apparatus further includes a pulverized fuel burner configured to inject pulverized fuel into the furnace together with air. The boiler of claim 1.

3. A control unit configured to adjust a diffusion ammonia supply amount, which is an ammonia supply amount to the furnace via the ammonia diffusion burner, and a premixed ammonia supply amount, which is an ammonia supply amount to the furnace via the ammonia premixed burner, based on a required load of the boiler; The control unit is configured to reduce the diffused ammonia supply amount in preference to the premixed ammonia supply amount when reducing a load on the boiler.

3. The boiler according to claim 1 or 2.

4. A pulverized fuel burner configured to inject pulverized fuel together with air into the furnace; The control unit is configured to adjust a pulverized fuel supply amount to the furnace via the pulverized fuel burner in addition to the diffusion ammonia supply amount and the premixed ammonia supply amount; The control unit is configured to reduce the diffusion ammonia supply amount in preference to the premixed ammonia supply amount and to reduce the premixed ammonia supply amount in preference to the pulverized fuel supply amount when reducing a load of the boiler. The boiler according to claim 3.

5. A pulverized fuel burner configured to inject pulverized fuel together with air into the furnace; The control unit is configured to adjust a pulverized fuel supply amount to the furnace via the pulverized fuel burner in addition to the diffusion ammonia supply amount and the premixed ammonia supply amount; The control unit is configured to reduce the diffused ammonia supply amount in preference to the premixed ammonia supply amount while maintaining an ammonia co-firing ratio when reducing a load of the boiler, The ammonia co-firing ratio is a ratio of the sum of the diffusion ammonia supply amount and the premixed ammonia supply amount to the total of the diffusion ammonia supply amount, the premixed ammonia supply amount, and the pulverized fuel supply amount on a calorific value basis. The boiler according to claim 3.

6. A method for retrofitting a boiler including a furnace, an oil burner for injecting oil into the furnace, and a pulverized fuel burner for injecting pulverized fuel together with air into the furnace, comprising: converting the oil burner into an ammonia diffusion burner for injecting liquid ammonia into the furnace; converting the pulverized fuel burner into an ammonia premix burner for injecting a premix of gaseous ammonia and air into the furnace; A method for modifying a boiler comprising:

7. In the step of modifying the oil burner, an oil nozzle of the oil burner is replaced with a liquid ammonia nozzle for spraying liquid ammonia into the furnace; In the step of modifying the pulverized fuel burner, a premixed gas forming unit for forming a premixed gas of gaseous ammonia and air is provided in the pulverized fuel burner. The method for retrofitting a boiler according to claim 6.

8. A method for retrofitting a boiler including a furnace, an oil burner for injecting oil into the furnace, and a pulverized fuel burner for injecting pulverized fuel together with air into the furnace, comprising: converting the oil burner into an ammonia premix burner for injecting a premix of gaseous ammonia and air into the furnace; converting the pulverized fuel burner into an ammonia diffusion burner for injecting liquid ammonia into the furnace; A method for modifying a boiler comprising:

9. A method for operating a boiler according to claim 1 or 2, comprising: The method includes a step of adjusting a diffusion ammonia supply amount, which is an ammonia supply amount to the furnace via the ammonia diffusion burner, and a premixed ammonia supply amount, which is an ammonia supply amount to the furnace via the ammonia premixing burner, based on a required load of the boiler; In the step, when the load of the boiler is reduced, the diffused ammonia supply amount is reduced in preference to the premixed ammonia supply amount. How to operate a boiler.

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