Ammonia fuel supply unit and boiler system

Abstract

To provide an ammonia fuel supply unit capable of decreasing a risk that the operation of a boiler is adversely influenced by the leakage of ammonia fuel, and a boiler system.SOLUTION: The ammonia fuel supply unit according to some embodiments of the present invention, comprises an ammonia fuel supply pipe configured to supply a boiler with ammonia fuel, and an outer pipe disposed to surround at least a portion of the ammonia fuel supply pipe to form a double pipe structure in combination with the ammonia fuel supply pipe.SELECTED DRAWING: Figure 2A

Description

Technical Field

[0001] The present disclosure relates to an ammonia fuel supply unit and a boiler system.

Background Art

[0002] A boiler in which ammonia is supplied into a furnace as fuel is known. For example, in the boiler disclosed in Patent Document 1, ammonia co-firing is performed in which ammonia burns in a furnace together with coal.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The amount of ammonia used as fuel is very large compared to, for example, the amount of ammonia used as a catalyst for denitrification of combustion gas. Therefore, if ammonia as fuel leaks during the process of being supplied to the boiler, the impact on the operation of the boiler is significant, and an effective measure for suppressing leakage is desired. However, the above patent documents do not disclose a specific configuration of the suppression measure.

[0005] An object of the present disclosure is to provide an ammonia fuel supply unit and a boiler system capable of reducing the risk of affecting the operation of the boiler due to leakage of ammonia fuel.

Means for Solving the Problems

[0006] The ammonia fuel supply unit according to at least one embodiment of the present disclosure is an ammonia fuel supply pipe configured to supply ammonia fuel to a boiler, The system includes an outer pipe that is positioned to surround at least a portion of the ammonia fuel supply pipe and forms a double-pipe structure together with the ammonia fuel supply pipe.

[0007] A boiler system according to at least one embodiment of the present disclosure is The ammonia fuel supply unit, The system includes a boiler that generates steam using combustion gas produced by the combustion of ammonia fuel supplied from the ammonia fuel supply unit as a heat source. [Effects of the Invention]

[0008] According to this disclosure, it is possible to provide an ammonia fuel supply unit and a boiler system that can reduce the risk of boiler operation being affected by ammonia fuel leakage. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic diagram of a boiler system according to one embodiment. [Figure 2A] This is a schematic diagram of the ammonia fuel supply unit according to the first embodiment. [Figure 2B] This is a schematic diagram of the ammonia fuel supply unit according to the second embodiment. [Figure 2C] This is a schematic diagram of the ammonia fuel supply unit according to the third embodiment. [Figure 2D] This is a schematic diagram of the ammonia fuel supply unit according to the fourth embodiment. [Figure 3] Figures 2A to 2D show a conceptual enlarged view of the region enclosed by the dashed line A. [Figure 4] Figures 2A and 2C show a conceptual enlarged view of the region enclosed by the dashed line B. [Modes for carrying out the invention]

[0010] An embodiment of the present invention will be described below with reference to the drawings. Note that the present invention is not limited by this embodiment, and if there are multiple embodiments, they may be constructed by combining each embodiment. In the following description, "up" or "above" refers to the upper side in the vertical direction, and "down" or "below" refers to the lower side in the vertical direction; the vertical direction is not precise and includes errors. Furthermore, the dimensions, materials, shapes, relative arrangements, etc., of the components described or shown in the drawings as embodiments are not intended to limit the scope of this disclosure, but are merely illustrative examples. For example, expressions describing relative or absolute arrangements such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial" should not only strictly describe such arrangements, but also describe states of relative displacement with tolerances or angles or distances that allow for the same function to be achieved. For example, expressions such as "identical," "equal," and "homogeneous" that describe things being in an equal state not only describe a state of being strictly equal, but also describe a state in which there is a tolerance or a difference that is sufficient to achieve the same function. For example, expressions describing shapes such as squares or cylinders shall not only represent geometrically precise shapes such as squares or cylinders, but also shapes that include protrusions, chamfers, etc., to the extent that the same effect can be achieved. On the other hand, expressions such as "possessing," "including," or "having" one component are not exclusive expressions that exclude the existence of other components. Note that similar configurations may be denoted by the same reference numerals and their explanations may be omitted.

[0011] <1. Overall configuration of boiler system 1> Figure 1 is a schematic diagram showing a boiler system 1 in this embodiment, which includes a boiler that primarily uses ammonia fuel and other fuels besides ammonia fuel.

[0012] The boiler 10 included in the boiler system 1 of this embodiment is a boiler capable of burning other fuels and ammonia fuel by a burner, and generating superheated steam by exchanging the heat generated by this combustion with feed water or steam. As the other fuel, solid fuels such as biomass fuel and coal are used. Coal as a solid fuel is, for example, pulverized fine coal fuel. Further, the ammonia fuel is liquid ammonia or ammonia gas.

[0013] The boiler 10 has a furnace 11, combustion devices 20, 50, and a combustion gas passage 12. The furnace 11 has a hollow shape of a square cylinder and is installed along the vertical direction. The furnace wall 101 constituting the inner wall surface of the furnace 11 is composed of a plurality of heat transfer tubes and fins connecting the heat transfer tubes to each other, and recovers the heat generated by the combustion of the pulverized coal fuel by exchanging heat with the water or steam flowing inside the heat transfer tubes, and suppresses the temperature rise of the furnace wall 101.

[0014] The combustion devices 20, 50 are installed in the lower region of the furnace 11. In this embodiment, the combustion device 20 is configured to inject pulverized coal fuel into the furnace 11. Further, the combustion device 50 is configured to inject ammonia fuel into the furnace 11.

[0015] 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 51. At the tip of each burner 21, an injection nozzle (not shown) configured to inject pulverized coal fuel into the furnace 11 is provided. Further, at the tip of each ammonia burner 51, an ammonia injection nozzle (not shown) is provided. When a liquid ammonia injection method in which liquid ammonia is injected into the furnace 11 is adopted, the ammonia injection nozzle may be a two-fluid injection nozzle configured to atomize and inject liquid ammonia by an atomizing fluid such as steam, or a one-fluid injection nozzle configured to inject only liquid ammonia. Further, when an ammonia gas injection method in which ammonia gas is injected into the furnace 11 is adopted, the ammonia injection nozzle may be a gas injection nozzle. The burner 21 and the ammonia burner 51 are arranged at equal intervals along the circumferential direction of the furnace 11 (for example, four burners installed at each corner of the square furnace 11 are taken as one set) and are arranged in a plurality of stages along the vertical direction. In the example of FIG. 1, two sets of burners 21 are arranged in two stages, and four sets of ammonia burners 51 are arranged in four stages. In FIG. 1, for the sake of illustration, only two of the burners in one set are shown, and the reference numerals 21 and 51 are attached to each set. The shape of the furnace, the number of stages of the burners, the number of burners in one stage, the arrangement of the burners, etc. are not limited to this embodiment. Also, the combustion method in the furnace 11 may be either a swirling combustion method or a counter combustion method. Depending on the combustion method adopted, the shape of the furnace 11 and the arrangements of the plurality of burners 21 and the plurality of ammonia burners 51 may all be appropriately changed.

[0016] Each of the burners 21 of the combustion device 20 is connected to a plurality of mills (pulverizers) 31A, 31B (hereinafter may be collectively referred to as "mill 31") via a plurality of pulverized coal fuel supply pipes 22A, 22B (hereinafter may be collectively referred to as "pulverized coal fuel supply pipe 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 roller and the pulverizing table is conveyed 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, it is classified into pulverized coal fuel having a particle size suitable for combustion in the burner 21 and coarse pulverized coal fuel having a particle size larger than the above-mentioned particle size. The pulverized coal fuel passes through the classifier and is supplied to the burner 21 via the pulverized coal fuel supply pipe 22 together with the primary air. The coarse pulverized coal fuel that has not passed through the classifier falls onto the pulverizing table inside the mill 31 due to its own weight and is pulverized again.

[0017] The primary air (conveyor gas, oxidizing gas) supplied to the mill 31 is sent to the mill 31 via the air pipe 30 from a primary air fan 33 (PAF) that takes in outside air. The air pipe 30 includes a hot air guide pipe 30A through which hot air heated by the air heater 42 flows from the air sent from the primary air fan 33, a cold air guide pipe 30B through which cold air at near room temperature flows from the air sent from the primary air fan 33 that does not pass through the air heater 42, and a conveyor gas passage 30C through which the hot air and cold air flow together.

[0018] The ammonia burner 51 of the combustion device 50 is connected to the ammonia fuel supply unit 90. The ammonia fuel supply unit 90 in 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. If an ammonia gas injection method is adopted, a vaporizer 81 (see Figures 2A and 2B) for vaporizing liquid ammonia may be provided in the ammonia fuel supply pipe 92 (details will be described later). Furthermore, if a liquid ammonia injection method is adopted, the ammonia fuel supply unit 90 may further include an atomizing fluid supply pipe (not shown) for supplying atomizing fluid to the combustion device 50.

[0019] An air register 23 is provided on the outside of the furnace 11 at the mounting positions of the burner 21 and the ammonia burner 51, and one end of an air duct 24 is connected to this air register 23. A forced draft fan (FDF) 32 is connected to the other end of the air duct 24. The air supplied from the forced draft fan 32 is heated by an air preheater 42 installed in the air duct 24 (details will be described later), and is supplied to the burner 21 as secondary air (combustion air, oxidizing gas) via the air register 23 and introduced into the furnace 11.

[0020] The combustion gas passage 12 is connected to the upper vertical part of the furnace 11. The combustion gas passage 12 is equipped with superheaters 102A, 102B, 102C (hereinafter sometimes collectively referred to as "superheater 102"), reheaters 103A, 103B (hereinafter sometimes collectively referred to as "reheater 103"), and an economizer 104 as heat exchangers for recovering heat from the combustion gas. Heat exchange takes place between the combustion gas generated in the furnace 11 and the feedwater or steam circulating inside each heat exchanger. Note that the arrangement and shape of each heat exchanger are not limited to the configuration shown in Figure 1.

[0021] Downstream of the combustion gas passage 12 is a flue 13 through which the combustion gas, whose heat has been recovered by the heat exchanger, is discharged. An air preheater (air heater) 42 is installed between the flue 13 and the air duct 24, and heat exchange takes place between the air flowing through the air duct 24 and the combustion gas flowing through the flue 13. By heating the primary air supplied to the mill 31 and the secondary air supplied to the burner 21, heat is further recovered from the combustion gas after heat exchange with water or steam.

[0022] Furthermore, a denitrification device 43 may be provided in the flue 13 at a position upstream of the air preheater 42. The denitrification device 43 supplies a reducing agent, such as ammonia or urea solution, which has the effect of reducing nitrogen oxides, to the combustion gas flowing through the flue 13. The reaction between the nitrogen oxides (NOx) in the combustion gas to which the reducing agent has been supplied and the reducing agent is promoted by the catalytic action of a denitrification catalyst installed in the denitrification device 43, thereby removing and reducing nitrogen oxides in the combustion gas. A gas duct 41 is connected downstream of the air preheater 42 in the flue 13. The gas duct 41 is equipped with dust collection devices 44, such as an electrostatic precipitator, to remove ash and other particles from the combustion gas, and environmental devices such as a desulfurization device 46 to remove sulfur oxides, as well as an induced draft fan (IDF) 45 to guide the exhaust gas to these environmental devices. The downstream end of the gas duct 41 is connected to the chimney 47, and the combustion gas treated by the environmental devices is discharged outside the system as exhaust gas.

[0023] In the boiler 10, when multiple mills 31 are driven, the crushed and classified pulverized coal fuel is supplied to the burner 21 via the pulverized coal fuel supply pipe 22 along with primary air. In addition, ammonia fuel is supplied to the ammonia burner 51 from the ammonia fuel supply unit 90. Furthermore, secondary air heated by the air preheater 42 is supplied to the burner 21 and the ammonia burner 51 via the air duct 24 and the air register 23. Burner 21 injects a pulverized coal fuel mixture, which is a mixture of pulverized coal fuel and primary air, into the furnace 11, along with secondary air. The pulverized coal fuel mixture injected into the furnace 11 ignites and reacts with the secondary air to form a flame. Ammonia burner 51 injects ammonia fuel along with secondary air into the furnace 11. The ammonia fuel injected into the furnace 11 reacts with the secondary air and burns. The high-temperature combustion gases generated by the combustion of pulverized coal fuel and ammonia fuel rise inside the furnace 11 and flow into the combustion gas passage 12. Furthermore, the timing of injecting ammonia fuel into the furnace 11 may be after the temperature inside the furnace 11 has risen to a certain temperature due to the combustion of pulverized coal fuel. For example, after the boiler 10 is started up and pulverized coal fuel is exclusively burned, ammonia fuel may be injected into the furnace 11, and ammonia co-firing of ammonia fuel and pulverized coal fuel may occur. After that, the injection of pulverized coal fuel may be stopped and ammonia exclusive burning may be performed. Furthermore, in this embodiment, air is used as the oxidizing gas (primary air, secondary air), but it may also be a gas with a higher or lower oxygen content than air, and stable combustion can be achieved in the furnace 11 by adjusting the ratio of oxygen to the supplied fuel amount to an appropriate range.

[0024] The combustion gas flowing into the combustion gas passage 12 undergoes heat exchange with water and steam in the superheater 102, reheater 103, and economizer 104 located inside the combustion gas passage 12, before being discharged into the flue 13. There, nitrogen oxides are removed in the denitrification device 43, and after heat exchange with primary and secondary air in the air preheater 42, it is further discharged into the gas duct 41. Ash and other contaminants are removed in the dust collector 44, and sulfur oxides are removed in the desulfurization device 46 before being discharged out of the system through the chimney 47. Note that the arrangement of each heat exchanger in the combustion gas passage 12 and each device from the flue 13 to the gas duct 41 does not necessarily have to be in the order described above with respect to the flow of combustion gas.

[0025] The boiler described herein is not limited to the embodiments described above. As the solid fuel used in the boiler, coal, biomass fuel, petroleum coke (PC), petroleum residue, etc., may be used instead of or in conjunction with pulverized coal fuel. Furthermore, the fuel used in boilers combined with ammonia fuel is not limited to solid fuels; liquid fuels such as heavy oil, light oil, heavy crude oil, and industrial wastewater can also be used. Gaseous fuels such as natural gas, various petroleum gases, and by-product gases generated in steelmaking processes can also be used. Furthermore, this can also be applied to co-firing boilers that use a combination of these various fuels.

[0026] <2. Configuration of the ammonia fuel supply unit 90> Refer to Figures 2A to 2D to illustrate the details of the configuration of the ammonia fuel supply unit 90. Figures 2A to 2D are conceptual diagrams of the ammonia fuel supply units 90A to 90D (90). Figure 3 is a conceptual enlarged view of the region enclosed by the dashed line A shown in Figures 2A to 2D. Figure 4 is a conceptual enlarged view of the region enclosed by the dashed line B shown in Figures 2A and 2C.

[0027] The ammonia fuel supply units 90A and 90B(90) illustrated in Figures 2A and 2B are applied to a boiler 10 employing an ammonia gas injection system. The ammonia fuel supply units 90C and 90D(90) illustrated in Figures 2C and 2D are applied to a boiler 10 employing a liquid ammonia injection system.

[0028] The ammonia fuel supply units 90A to 90D (90) illustrated in Figures 2A to 2D include, as described above, an ammonia fuel supply pipe 92 for supplying ammonia fuel stored in an ammonia tank 91 to the boiler 10. The ammonia fuel supply pipe 92 is a single pipe connected to the ammonia tank 91 and the combustion device 50 (see Figure 1) of the boiler 10. In the illustrated embodiment, the ammonia tank 91 is a tank installed outside the building 15 of the boiler 10, but in embodiments where ammonia fuel is supplied from, for example, a liquid ammonia production site or a large-scale storage facility, the ammonia tank 91 may not be provided. In this case, the upstream end of the ammonia fuel supply pipe 92 may be connected to a liquid ammonia pipeline.

[0029] The ammonia fuel supply units 90A and 90B illustrated in Figures 2A and 2B are each equipped with at least one vaporizer 81 in the ammonia fuel supply pipe 92. The vaporizer 81 is configured to vaporize the liquid ammonia supplied from the ammonia fuel supply unit 90. Therefore, the single pipes downstream of the vaporizer 81 in the ammonia fuel supply pipe 92 of the ammonia fuel supply units 90A and 90B each form a supply path for ammonia gas. As an example, the vaporizer 81 may directly or indirectly utilize steam or condensed water generated in the boiler 10, hot air generated using the waste heat of the boiler 10, or seawater outside the boiler system 1 as a heat source. The ammonia fuel supply pipes 92 of the ammonia fuel supply units 90C and 90D illustrated in Figures 2C and 2D are not equipped with a vaporizer 81. The ammonia fuel supply pipes 92 shown in the figures form a liquid ammonia supply path along their entire length.

[0030] <2-1. Examples of operation in ammonia fuel supply units 90A-90D> As shown in Figures 2A to 2D, the ammonia fuel supply units 90A to 90D (90) are arranged to surround at least a portion of the ammonia fuel supply pipe 92 and include an outer pipe 95 that forms a double-pipe structure together with the ammonia fuel supply pipe 92. The outer pipe 95 illustrated in the figures is arranged to surround a portion of the ammonia fuel supply pipe 92 in its extending direction, over the circumferential direction of the ammonia fuel supply pipe 92. In other embodiments, the outer pipe 95 may be arranged to surround the ammonia fuel supply pipe 92 over its entire flow path (not shown). In other words, the outer pipe 95 may be connected to the ammonia tank 91 and the combustion device 50.

[0031] According to the above configuration, a double-pipe structure is adopted in which at least a portion of the ammonia fuel supply pipe 92 is surrounded by an outer pipe 95, thereby reducing the risk of ammonia fuel leaking from the ammonia fuel supply unit 90. For example, in the examples of Figures 2A and 2B, the risk of ammonia gas leaking from the outer pipe 95 is reduced, and in the examples of Figures 2C and 2D, the risk of ammonia fuel, which is either liquid ammonia or ammonia gas, leaking from the outer pipe 95 is reduced. Thus, an ammonia fuel supply unit 90 is realized that can reduce the risk of the operation of the boiler 10 being affected by ammonia fuel leakage.

[0032] In the embodiments illustrated in Figures 2A to 2D, the outer pipe 95 is located only inside the building of the boiler 10, rather than outside the building. Therefore, the outer pipe 95 is not located outside the building 15 of the boiler 10, and the ammonia fuel supply pipe 92 is located as a single pipe. As shown in Figure 3, the ammonia fuel supply pipe 92 is installed to penetrate the wall portion of the building 15, and the upstream end of the outer pipe 95 is connected to the inner surface of the wall portion. If the ammonia fuel supply pipe 92 from the ammonia tank 91 (see Figures 2A to 2D) to the boiler 10 were all double pipes, it would lead to increased costs for the ammonia fuel supply unit 90. Furthermore, if ammonia fuel leaks inside the building of the boiler 10, rather than outside, it would have a greater impact on the operation of the boiler 10 because, for example, the inside of the building 15 would need to be ventilated. With the above configuration, the double pipe structure formed by the ammonia fuel supply pipe 92 and the outer pipe 95 is located only inside the building of the boiler 10. Therefore, it is possible to effectively reduce the risk of the operation of the boiler 10 being affected by ammonia fuel leakage while suppressing increased costs. Furthermore, as illustrated in Figures 2A and 2C, a double-pipe structure may be formed in a portion of the ammonia fuel supply pipe 92 located inside the building 15, or, as illustrated in Figures 2B and 2D, a double-pipe structure may be formed along the entire length of the ammonia fuel supply pipe 92 located inside the building 15. In either case, the above advantages can be obtained.

[0033] In the embodiments illustrated in Figures 2A to 2D, the outer pipe 95 forms a purge gas flow path between itself and the ammonia fuel supply pipe 92. The purge gas illustrated in Figures 2A and 2B is hot air. As a more specific example, the outer tube 95 is connected via an extraction tube 97 to a hot air duct 24A configured to guide hot air heated by an air heater 42 to a boiler 10. Therefore, hot air flows as purge gas in the intermediate space between the outer tube 95 and the ammonia fuel supply tube 92 shown in the figure. The purge gas illustrated in Figures 2C and 2D is unheated air (cold air). As a more specific example, the outer pipe 95 is connected via an air supply pipe 241 to a cold air duct 24B, which is an air duct 24 configured to guide atmospheric air to an air heater 42. Therefore, cold air flows as purge gas in the intermediate space between the outer pipe 95 and the ammonia fuel supply pipe 92 shown in the figure.

[0034] With the above configuration, even if ammonia fuel leaks from the ammonia fuel supply pipe 92, the ammonia fuel flows toward the boiler 10 together with the purge gas, so that the residual ammonia fuel in the intermediate space between the ammonia fuel supply pipe 92 and the outer pipe 95 can be suppressed.

[0035] <2-2. Examples of operation in ammonia fuel supply units 90A and 90C> In the embodiment illustrated in Figures 2A and 2C, a double-walled structure is formed in a portion of the ammonia fuel supply pipe 92 inside the building 15 of the boiler 10, and the other portion of the ammonia fuel supply pipe 92 is located inside the hot air duct 24A. Therefore, the ammonia fuel supply pipe 92 in the figures is provided so as to penetrate the wall portion constituting the hot air duct 24A, and the downstream end of the outer pipe 95 is connected to the hot air duct 24A. More specifically, as shown in Figure 4, the ammonia fuel supply pipe 92 includes an inner pipe 921 located inside the outer pipe 95, and a connecting pipe 922 located inside the hot air duct 24A and connected to the boiler 10 and the inner pipe 921. Note that in Figures 2A and 2C, the outer wall portion of the hot air duct 24A is virtually illustrated by a dashed line W (the same applies to Figures 2B and 2D).

[0036] According to the above configuration, even if ammonia fuel leaks from the connecting pipe 922, the ammonia fuel is guided to the boiler 10 by the hot air duct 24A. For example, in the embodiment shown in Figure 2A, even if ammonia gas leaks from the connecting pipe 922, the ammonia gas receives heat from the hot air, so condensation of the ammonia gas is unlikely to occur. The ammonia gas then flows through the inner space of the hot air duct 24A, indicated by the area enclosed by the dashed line W, and reaches the air nozzle provided in the boiler 10. After that, the ammonia gas is injected into the furnace 11. Also, in the embodiment shown in Figure 2C, even if liquid ammonia leaks from the connecting pipe 922, the liquid ammonia vaporizes into ammonia gas due to the heat received from the hot air. The ammonia gas flows through the inner space of the hot air duct 24A, indicated by the area enclosed by the dashed line W, and reaches the air nozzle. As described above, the leaked ammonia fuel, whether as ammonia gas or liquid ammonia, flows into the furnace 11 of the boiler 10, thus reducing the risk of the boiler 10's operation being affected by ammonia fuel leakage. Furthermore, since the outer tube 95 is not located inside the hot air duct 24A, and the double-tube structure is only used in a portion of the ammonia fuel supply tube 92, cost increases can be suppressed. Therefore, the risk of the boiler 10's operation being affected by ammonia fuel leakage can be effectively reduced while suppressing cost increases.

[0037] Referring to Figures 2A and 3, a more specific configuration is illustrated in which the purge gas flowing through the outer pipe 95 is hot air. The ammonia fuel supply unit 90A includes an extraction pipe 97 configured to send hot air extracted from the hot air duct 24A to the outer pipe 95. The hot air extracted from the extraction pipe 97 flows as purge gas between the outer pipe 95 and the inner pipe 921. The inner pipe 921 of the ammonia fuel supply unit 90A forms an ammonia gas supply passage on its inside, and the temperature of the ammonia gas flowing through this supply passage is lower than the temperature of the hot air supplied from the extraction pipe 97. With the above configuration, even if ammonia gas leaks from the inner pipe 921 of the ammonia fuel supply pipe 92, the ammonia gas receives heat from the hot air, so condensation of the ammonia gas is suppressed. Therefore, even if an ammonia gas leak occurs, the ammonia gas does not condense and is guided to the boiler 10 via the hot air duct 24A. Therefore, it is possible to suppress the residual ammonia gas between the inner pipe 921 and the outer pipe 95.

[0038] Referring to Figures 2C and 3, a more specific configuration is illustrated in which the purge gas flowing through the outer pipe 95 is cold air. The ammonia fuel supply unit 90C is equipped with an air supply pipe 241. In this example, the air supply pipe 241 is connected to the cold air duct 24B and the outer pipe 95. As a result, the cold air introduced by the air supply pipe 241 flows as purge gas between the outer pipe 95 and the inner pipe 921. The inner pipe 921 of the ammonia fuel supply unit 90C forms a liquid ammonia supply passage on its inside, and the temperature of the liquid ammonia flowing through this supply passage is approximately the same as the temperature of the cold air supplied from the air supply pipe 241. With the above configuration, since the cold air, which is unheated air that was in the atmosphere, flows as purge gas through the intermediate space between the outer pipe 95 and the inner pipe 921, the liquid ammonia flowing through the inner pipe 921 is less likely to change into ammonia gas, and vapor lock in the ammonia fuel supply pipe 92 can be suppressed. Furthermore, since the pressure in the intermediate space between the inner pipe 921 and the outer pipe 95 is lower than the supply pressure in the ammonia fuel supply pipe 92 shown in Figure 2C, even if liquid ammonia leaks from the inner pipe 921, the liquid ammonia vaporizes into ammonia gas and is sent to the hot air duct 24A by cold air acting as a purge gas. The ammonia gas then flows through the inner space of the hot air duct 24A, indicated by the area enclosed by the dashed line W, and is led to the boiler 10. Therefore, it is possible to suppress the residue of leaked liquid ammonia between the inner pipe 921 and the outer pipe 95. In other embodiments, the air supply pipe 241 does not necessarily have to be branched from the cold air duct 24B, and may be a single pipe connected to a blower (not shown) and an outer pipe 95.

[0039] <2-3. Examples of operation in the ammonia fuel supply unit 90C> The ammonia fuel supply unit 90C illustrated in Figure 2C is equipped with an insulating mechanism 120 provided on the outer surface of the connecting pipe 922. The insulating mechanism 120 in this example is an insulating material provided on the outer surface of the connecting pipe 922. With the above configuration, the heat input from the hot air flowing through the hot air duct 24A to the liquid ammonia flowing through the connecting pipe 922 can be suppressed, thereby suppressing vapor lock in the connecting pipe 922. Therefore, liquid ammonia can flow stably through the connecting pipe 922 of the ammonia fuel supply unit 90.

[0040] <2-4. Ammonia Detector 80> The ammonia fuel supply units 90A to 90D (90) illustrated in Figures 2A to 2D include ammonia detectors 80A to 80D (80) configured to detect ammonia fuel. The ammonia detectors 80A to 80D are located in at least one of the following spaces: the intermediate space between the ammonia fuel supply pipe 92 and the outer pipe 95, a space communicating with the intermediate space, or the space outside the outer pipe 95. As a more specific example, the ammonia detectors 80A and 80C illustrated in Figures 2A and 2C are located in the space between the outer wall of the hot air duct 24A, indicated by the dashed line W, and the connecting pipe 922 (i.e., the space communicating with the intermediate space). The ammonia detectors 80B and 80D illustrated in Figures 2B and 2D are located outside the outer pipe 95 (i.e., in the outer space). Although not shown in detail, ammonia detectors 80 according to other embodiments may be located in the intermediate space.

[0041] The ammonia detector 80 in this example is a laser-type gas measuring instrument configured to measure ammonia concentration based on the spectrum of laser light transmitted through the gas. The laser-type gas measuring instrument utilizes the principle that ammonia gas has a unique light absorption spectrum. It detects whether or not ammonia gas is present in the detection area by spectrally analyzing the output result of a photodetector that receives light irradiated toward the detection area where ammonia gas may be present. The ammonia detector 80 may be placed near the boiler 10 such that the furnace 11 of the boiler 10 is included in the detection area.

[0042] With the above configuration, the ammonia detector 80 can detect if ammonia fuel has leaked from the ammonia fuel supply pipe 92 or the outer pipe 95. Therefore, the ammonia fuel supply unit 90 can take post-incident measures after ammonia fuel has leaked. For example, in an embodiment in which the ammonia detector 80 is connected to an interlock (not shown) configured to cause a boiler trip, the interlock may be activated when the detection result of the ammonia detector 80 satisfies the specified stop conditions, causing a boiler trip. This allows the operator to take appropriate measures (for example, repair the piping from which ammonia fuel leaked) and then restart the operation of the boiler 10.

[0043] <3. Summary> Some embodiments of this disclosure can be understood, for example, as follows:

[0044] 1) An ammonia fuel supply unit (90) according to at least one embodiment of the present disclosure is an ammonia fuel supply pipe (92) configured to supply ammonia fuel to a boiler (10), The system includes an outer pipe (95) that is positioned to surround at least a portion of the ammonia fuel supply pipe and forms a double-pipe structure together with the ammonia fuel supply pipe.

[0045] When ammonia is used as fuel for a boiler, a large amount of ammonia is handled. Therefore, the impact on boiler operation when ammonia fuel leaks is significant. In this regard, according to the configuration of 1) above, a double-pipe structure is adopted in which at least a portion of the ammonia fuel supply pipe is surrounded by an outer pipe, thereby reducing the risk of ammonia fuel leaking from the ammonia fuel supply unit. Thus, an ammonia fuel supply unit is realized that can reduce the risk of boiler operation being affected by ammonia fuel leakage.

[0046] 2) In some embodiments, the ammonia fuel supply unit described in 1) above, The outer tube is located inside the boiler building, or outside the building.

[0047] If all ammonia fuel supply pipes are double-walled, it leads to increased costs for the ammonia fuel supply unit. Furthermore, if ammonia fuel leaks inside the boiler building, rather than outside, it has a greater impact on boiler operation because, for example, ventilation measures inside the building are required. In this respect, according to the configuration in 2) above, the double-walled structure formed by the ammonia fuel supply pipe and the outer pipe is located only inside the boiler building. Therefore, it is possible to effectively reduce the risk of boiler operation being affected by ammonia fuel leakage while suppressing increased costs.

[0048] 3) In some embodiments, the ammonia fuel supply unit is as described in 1) or 2) above, The outer pipe forms a flow path for purge gas between itself and the ammonia fuel supply pipe.

[0049] According to the configuration described in 3) above, even if ammonia fuel leaks from the ammonia fuel supply pipe, the ammonia fuel flows toward the boiler together with the purge gas, thus suppressing the residue of ammonia fuel between the ammonia fuel supply pipe and the outer pipe.

[0050] 4) In some embodiments, the ammonia fuel supply unit is as described in 3) above, The outer tube is connected to a hot air duct (24A) configured to guide hot air heated by an air heater (42) to the boiler. The ammonia fuel supply pipe is An inner tube (921) is positioned inside the outer tube, It includes a connecting pipe (922) positioned inside the hot air duct and connected to the boiler and the inner tube.

[0051] According to the configuration described in 4) above, even if ammonia fuel leaks from the connecting pipe, the ammonia fuel is guided to the boiler by the hot air duct. Since the leaked ammonia fuel flows into the inside of the boiler furnace, the risk of the boiler operation being affected by ammonia fuel leakage can be effectively reduced. In addition, since the double-pipe structure is only used in a portion of the ammonia fuel supply pipe, cost increases can be suppressed. Therefore, the risk of the boiler operation being affected by ammonia fuel leakage can be effectively reduced while suppressing cost increases.

[0052] 5) In some embodiments, the ammonia fuel supply unit described in 4) above, The aforementioned connecting pipe is further provided with an insulating mechanism (120) on its outer surface, The ammonia fuel supply pipe has an internal supply channel for liquid ammonia.

[0053] According to the configuration described in 5) above, the heat input from the hot air flowing through the hot air duct to the liquid ammonia flowing through the connecting pipe can be suppressed, thereby suppressing vapor lock in the connecting pipe. Consequently, liquid ammonia can flow stably through the connecting pipe of the ammonia fuel supply unit.

[0054] 6) In some embodiments, the ammonia fuel supply unit is as described in 4) or 5) above, The system further includes an air supply pipe (241) configured to supply air from the atmosphere to the outer pipe without applying heat treatment, The ammonia fuel supply pipe has an internal supply channel for liquid ammonia.

[0055] According to the configuration described in 6) above, the air that was in the atmosphere flows directly through the outer tube as a purge gas, so the heat input from the purge gas to the liquid ammonia flowing through the inner tube is suppressed. Liquid ammonia is less likely to change into ammonia gas, and vapor lock in the ammonia fuel supply pipe can be suppressed. In addition, even if liquid ammonia leaks from the inner tube, the liquid ammonia vaporizes into ammonia gas and flows to the hot air duct by the air acting as the purge gas. After that, the ammonia gas flows inside the hot air duct and is guided to the boiler. Therefore, the residue of leaked liquid ammonia between the inner and outer tubes can be suppressed.

[0056] 7) In some embodiments, the ammonia fuel supply unit is as described in 4) above, The system further comprises an extraction pipe (97) configured to send the hot air extracted from the hot air duct to the outer pipe, The inner pipe forms an ammonia gas supply passage on its interior.

[0057] According to the configuration described in 7) above, hot air extracted from the hot air duct flows through the ammonia fuel supply pipe and the outer pipe. Therefore, even if ammonia gas leaks from the inner pipe of the ammonia fuel supply pipe, the ammonia gas is guided to the boiler via the hot air duct without condensing. Consequently, the retention of leaked ammonia gas between the inner and outer pipes can be suppressed.

[0058] 8) In some embodiments, an ammonia fuel supply unit according to any one of 1) to 7) above, The system further includes an ammonia detector (80) provided in at least one of the intermediate space between the ammonia fuel supply pipe and the outer pipe, a space communicating with the intermediate space, or an outer space in the outer pipe, and configured to detect ammonia fuel.

[0059] According to the configuration described in 8) above, it is possible to detect ammonia fuel leaking from the ammonia supply pipe or from the outer pipe. Therefore, the ammonia fuel supply unit can take post-incident measures after an ammonia fuel leak occurs.

[0060] 9) A boiler system (1) according to at least one embodiment of the present disclosure is: An ammonia fuel supply unit (90) as described in any of 1) to 8) above, The system includes a boiler (10) that generates steam using combustion gas produced by the combustion of ammonia fuel supplied from the ammonia fuel supply unit as a heat source.

[0061] According to the configuration in 9) above, a boiler system is realized that can reduce the risk of the boiler's operation being affected by ammonia fuel leakage, for the same reasons as in 1) above. [Explanation of Symbols]

[0062] 1: Boiler System 10: Boiler 15: Building 24A: Hot air duct 42: Air heater 80: Ammonia detector 90: Ammonia fuel supply unit 92: Ammonia fuel supply pipe 95:Outer tube 97: Tracheal extraction tube 120: Thermal insulation mechanism 241: Air supply pipe 921 :Inner tube 922: Connecting pipe

Claims

1. an ammonia fuel supply pipe configured to supply ammonia fuel to a boiler, An outer tube is positioned to surround at least a portion of the ammonia fuel supply pipe and together with the ammonia fuel supply pipe to form a double-tube structure. Equipped with, An intermediate space for the flow of purge gas is formed between the outer pipe and the ammonia fuel supply pipe. The outer tube is located inside the boiler building, or outside the building, but only inside the building. The ammonia fuel supply pipe is installed so as to penetrate the wall portion that constitutes the building, The upstream end of the outer tube is connected to the inner surface of the wall portion. Ammonia fuel supply unit.

2. an ammonia fuel supply pipe configured to supply ammonia fuel to a boiler, An outer tube is positioned to surround at least a portion of the ammonia fuel supply pipe and together with the ammonia fuel supply pipe to form a double-tube structure. Equipped with, An intermediate space for the flow of purge gas is formed between the outer pipe and the ammonia fuel supply pipe. The outer tube is connected to a hot air duct configured to guide hot air heated by an air heater to the boiler. The ammonia fuel supply pipe is An inner tube positioned inside the outer tube, It includes a connecting pipe positioned inside the hot air duct and connected to the boiler and the inner tube. Ammonia fuel supply unit.

3. The aforementioned connecting pipe is further equipped with an insulating mechanism provided on its outer surface, The ammonia fuel supply pipe has a liquid ammonia supply passage on its inside. The ammonia fuel supply unit according to claim 2.

4. The system further includes an air supply pipe configured to deliver air from the atmosphere to the outer tube without applying heat treatment, The ammonia fuel supply pipe has a liquid ammonia supply passage on its inside. The ammonia fuel supply unit according to claim 2.

5. The system further comprises an extraction pipe configured to send the hot air extracted from the hot air duct to the outer pipe, The inner pipe forms an ammonia gas supply passage on its interior. The ammonia fuel supply unit according to claim 2.

6. The system further comprises an ammonia detector provided in at least one of the following spaces: the intermediate space between the ammonia fuel supply pipe and the outer pipe, the space communicating with the intermediate space, or the outer space in the outer pipe, and configured to detect ammonia fuel. The ammonia fuel supply unit according to claim 1 or 2.

7. an ammonia fuel supply pipe configured to supply ammonia fuel to a boiler, An outer tube is positioned to surround at least a portion of the ammonia fuel supply pipe and together with the ammonia fuel supply pipe to form a double-tube structure. Equipped with, Between the outer tube and the ammonia fuel supply tube, an intermediate space is formed for the purge gas to flow toward the boiler. If the ammonia fuel leaks from the ammonia fuel supply pipe into the intermediate space, the ammonia fuel is configured to flow through the intermediate space together with the purge gas and be guided to the boiler. Ammonia fuel supply unit.

8. an ammonia fuel supply unit according to claim 1 or 2, The boiler generates steam using combustion gas produced by the combustion of ammonia fuel supplied from the ammonia fuel supply unit as a heat source. A boiler system equipped with [a specific feature / feature].

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