Ammonia combustion apparatus

Abstract

To mix fuel using ammonia with combustion air for stable combustion, suppress an increase in a combustion temperature, and prevent damage of a tip part, etc. of a fuel feeding pipe in the vicinity of a combustion part.SOLUTION: When fuel using ammonia NH3 is ejected from a fuel ejection port 11 provided at a tip part of a fuel feeding pipe 10, is mixed with combustion air Air guided from an outer periphery of the fuel feeding pipe and is burned in a combustion part, an ammonia decomposition device 40 for decomposing the ammonia into hydrogen gas and nitrogen gas is provided in the fuel feeding pipe, a result obtained by detecting a temperature in the vicinity of the combustion part by using a temperature sensor 31 is output to a control device 30, and the amount of ammonia to be decomposed into hydrogen gas H2 and nitrogen gas N2 by using the ammonia decomposition device is controlled by the control device.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to an ammonia combustion device that provides a fuel supply pipe that supplies ammonia-based fuel with a fuel outlet at the tip of the fuel supply pipe for ejecting the fuel, mixes the fuel ejected from the fuel outlet with combustion air introduced from the outer periphery of the fuel supply pipe, and combusts the fuel in a combustion section. In particular, the ammonia combustion device is characterized in that, when the ammonia in the fuel is decomposed into hydrogen gas and nitrogen gas and combusted, the combustion temperature is increased by the combustion of the hydrogen resulting from the decomposition of ammonia, and damage to the tip of the fuel supply pipe and the like is prevented. [Background technology]

[0002] 2. Description of the Related Art Combustion devices that mix fuel with combustion air and combust the mixture generally use hydrocarbon fuels as the fuel.

[0003] However, when a hydrocarbon fuel is mixed with combustion air and burned in such a combustion device, there is a problem in that a large amount of greenhouse gases such as carbon dioxide is generated.

[0004] In recent years, there has been a demand for reducing greenhouse gases such as carbon dioxide, and the use of fuels other than hydrocarbon fuels has been considered.

[0005] In addition, it has been known to use ammonia as a fuel in a combustion device, but ammonia-based fuel has poor combustibility compared to hydrocarbon fuel, and it is difficult to completely combust it, and it is prone to misfires when combusted at low temperatures. In addition, ammonia generates fuel NOx, which increases the amount of NOx generated.

[0006] In order to burn fuel using ammonia, which has poor combustibility, Patent Document 1 discloses a method in which a part of the ammonia is thermally decomposed into hydrogen gas and nitrogen gas, and the hydrogen gas and nitrogen gas are mixed with the remaining ammonia to form a reformed ammonia fuel, which is then mixed with combustion air and burned.

[0007] Moreover, Patent Document 2 discloses an ammonia decomposition catalyst that decomposes ammonia into hydrogen gas and nitrogen gas.

[0008] Here, as shown in the above-mentioned Patent Document 2, when the hydrogen gas and nitrogen gas obtained by decomposing ammonia with an ammonia decomposition catalyst are mixed with combustion air and burned in a furnace by a burner, if the temperature inside the furnace becomes high (about 800°C or higher), the amount of NOx contained in the combustion exhaust gas increases rapidly, causing a problem of environmental damage.

[0009] Also, Patent Document 3 discloses a system in which a first supply path is provided for supplying reformed ammonia fuel, obtained by decomposing a part of ammonia fuel into hydrogen gas and nitrogen gas by an ammonia decomposition device, to a burner, and a second supply path is provided for supplying ammonia fuel as is to the burner, and the amount of ammonia fuel supplied to the burner through the first supply path and the second supply path is controlled by a control device based on the environmental condition in the furnace detected by an in-furnace environment detection sensor, and the ammonia fuel is mixed with combustion air in the burner and burned in the furnace.

[0010] However, Patent Documents 1 to 3 do not disclose an ammonia combustion device in which a fuel outlet for ejecting ammonia-based fuel is provided at the tip of a fuel supply pipe that supplies the fuel, and the fuel ejected from the fuel outlet is mixed with combustion air introduced from the outer periphery of the fuel supply pipe and combusted in a combustion section. Furthermore, in such an ammonia combustion device, when ammonia in an ammonia-based fuel is decomposed into hydrogen gas and nitrogen gas and combusted, the combustion temperature increases due to the combustion of the hydrogen resulting from the decomposition of ammonia, and damage to the tip of the fuel supply pipe, etc. is prevented. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] Japanese Patent Application Publication No. 7-331265 [Patent Document 2] JP 2012-5926 A [Patent Document 3] JP 2023-39681 A DISCLOSURE OF THEINVENTION [Problem to be solved by the invention]

[0012] The present invention has an ammonia combustion device in which a fuel outlet for ejecting ammonia-based fuel is provided at the tip of a fuel supply pipe that supplies the fuel, and the fuel ejected from the fuel outlet is mixed with combustion air introduced from the outer periphery of the fuel supply pipe and combusted in a combustion section. An object of the present invention is to suppress an increase in combustion temperature due to the combustion of the hydrogen resulting from the decomposition of ammonia when the ammonia in the ammonia-based fuel is decomposed into hydrogen gas and nitrogen gas and combusted, and to prevent damage to the tip of the fuel supply pipe near the combustion section, etc. [Means for solving the problem]

[0013] In order to solve the above-mentioned problems, the ammonia combustion apparatus according to the present invention provides an ammonia combustion apparatus in which a fuel outlet for ejecting ammonia-based fuel is provided at the tip of a fuel supply pipe that supplies the fuel, and the fuel ejected from the fuel outlet is mixed with combustion air introduced from the outer periphery of the fuel supply pipe and combusted in a combustion section, the fuel supply pipe is provided with an ammonia decomposition device for decomposing ammonia into hydrogen gas and nitrogen gas, a temperature sensor is provided for detecting the temperature in the vicinity of the combustion section where the fuel and combustion air are mixed and combusted, and a control device is provided for controlling the ammonia decomposition device based on the temperature detected by the temperature sensor, and the control device increases the amount of ammonia decomposed into hydrogen gas and nitrogen gas by the ammonia decomposition device when the temperature detected by the temperature sensor is low, while decreasing the amount of ammonia decomposed into hydrogen gas and nitrogen gas by the ammonia decomposition device when the temperature detected by the temperature sensor is high.

[0014] In the ammonia combustion apparatus of the present invention, the temperature near the combustion section where the fuel and combustion air are mixed and burned is detected by a temperature sensor, and when the temperature detected by the temperature sensor is high, the control device reduces the amount of ammonia decomposed into hydrogen gas and nitrogen gas by the ammonia decomposition device, thereby reducing the amount of hydrogen gas led to the combustion section, suppressing an increase in the combustion temperature during combustion and preventing damage to the tip of the fuel supply pipe near the combustion section, etc.

[0015] Here, in the ammonia combustion apparatus according to the present invention, the ammonia decomposition apparatus can be provided with at least one of a catalytic reforming section containing a catalyst that decomposes ammonia into hydrogen gas and nitrogen gas, and a thermal reforming section that heats ammonia to decompose it into hydrogen gas and nitrogen gas.

[0016] In the case where the ammonia decomposition device is provided with at least the thermal reforming unit, the control device can change the temperature at which the ammonia is heated in the thermal reforming unit when controlling the amount of ammonia decomposed into hydrogen gas and nitrogen gas by the ammonia decomposition device. In this case, when the temperature at which the ammonia is heated in the thermal reforming unit is increased, the decomposition of ammonia is promoted and the amount of ammonia decomposed into hydrogen gas and nitrogen gas increases, whereas when the temperature at which the ammonia is heated is decreased, the decomposition of ammonia is suppressed and the amount of ammonia decomposed into hydrogen gas and nitrogen gas decreases.

[0017] Furthermore, in the ammonia combustion apparatus according to the present invention, when the fuel supply pipe guides the ammonia-based fuel to a fuel outlet provided at the tip of the fuel supply pipe, a first supply passage that guides the ammonia-based fuel through the ammonia decomposition device and a second supply passage that guides the ammonia-based fuel without passing through the ammonia decomposition device are provided, and when the temperature detected by the temperature sensor is low, the control device increases the amount of ammonia-based fuel guided to the first supply passage to increase the amount of ammonia decomposed into hydrogen gas and nitrogen gas by the ammonia decomposition device, while when the temperature detected by the temperature sensor is high, the amount of ammonia-based fuel guided to the second supply passage is increased to decrease the amount of ammonia decomposed into hydrogen gas and nitrogen gas by the ammonia decomposition device.

[0018] In the ammonia combustion apparatus according to the present invention, a flame stabilizing member can be provided on the outer periphery of the fuel supply pipe upstream of the fuel outlet at the tip of the fuel supply pipe in the fuel flow direction, and the temperature sensor can be provided in the vicinity of the flame stabilizing member. In this way, when a flame stabilizing member is provided on the outer periphery of the fuel supply pipe at a position upstream of the fuel outlet at the tip of the fuel supply pipe in the fuel flow direction, the flame stabilizing member stores heat of the flame and maintains a high temperature, preventing the flame in the combustion section from going out, and by providing the temperature sensor in the vicinity of the flame stabilizing member, it becomes possible to prevent the temperature of the combustion section from becoming too high during combustion, which would cause the flame stabilizing member to be damaged.

[0019] In the ammonia combustion apparatus according to the present invention, the above-mentioned ammonia combustion apparatus can be provided inside a radiant tube. Effect of the Invention

[0020] In the ammonia combustion apparatus of the present invention, as described above, an ammonia decomposition device for decomposing ammonia into hydrogen gas and nitrogen gas is provided in the fuel supply pipe, and a control device for controlling the ammonia decomposition device is provided. The temperature in the vicinity of the combustion section where the fuel using ammonia and combustion air are mixed and burned is detected by a temperature sensor. When the temperature detected by the temperature sensor is low, the control device increases the amount of ammonia decomposed into hydrogen gas and nitrogen gas by the ammonia decomposition device, while when the temperature detected by the temperature sensor is high, the control device decreases the amount of ammonia decomposed into hydrogen gas and nitrogen gas by the ammonia decomposition device.

[0021] As a result, in the ammonia combustion apparatus according to the present invention, when the temperature in the vicinity of the combustion section where the fuel and combustion air are mixed and burned is low, the control device increases the amount of ammonia decomposed by the ammonia decomposer into hydrogen gas and nitrogen gas, thereby increasing the amount of hydrogen gas contained in the fuel led to the combustion section, so that the fuel using ammonia can be mixed with the combustion air and burned reliably, and when the temperature in the vicinity of the combustion section where the fuel and combustion air are mixed and burned is high, the control device reduces the amount of ammonia decomposed by the ammonia decomposer into hydrogen gas and nitrogen gas, thereby reducing the amount of hydrogen gas contained in the fuel led to the combustion section, so that the combustion temperature in the combustion section is prevented from becoming high and damage to the tip of the fuel supply pipe near the combustion section, etc. can be prevented. [Brief description of the drawings]

[0022] [Figure 1] FIG. 1 is a schematic side view illustrating a state in which, in an ammonia combustion apparatus according to a first embodiment of the present invention, the amount of ammonia used as fuel decomposed into hydrogen gas and nitrogen gas by an ammonia decomposer is adjusted by a control device, the fuel is ejected from a fuel ejection port provided at the tip of a fuel supply pipe, and the fuel is mixed with combustion air introduced from the outer periphery of the fuel supply pipe and burned in a combustion tube. [Diagram 2] FIG. 2 is a schematic front view illustrating a state in which a flame stabilizer is provided on the outer periphery of the tip end of the fuel supply pipe in the ammonia combustion apparatus according to the first embodiment. [Diagram 3] FIG. 11 is a schematic side view illustrating a modification of the ammonia combustion apparatus according to the first embodiment, in which the control device adjusts the amount of ammonia used as fuel decomposed into hydrogen gas and nitrogen gas by the ammonia decomposition device. [Figure 4]FIG. 11 is a schematic side view illustrating an ammonia combustion apparatus according to a second embodiment of the present invention, in which the amount of ammonia used as fuel is decomposed into hydrogen gas and nitrogen gas by an ammonia decomposition device, adjusted, ejected from a fuel outlet provided at the tip of a fuel supply pipe, mixed with combustion air introduced from the outer periphery of the fuel supply pipe, and combusted in a radiant tube. BEST MODE FOR CARRYING OUT THEINVENTION

[0023] Hereinafter, an ammonia combustion apparatus according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. Note that the ammonia combustion apparatus according to the present invention is not limited to the following embodiment, and can be appropriately modified and implemented within the scope of the invention.

[0024] (Embodiment 1) In the ammonia combustion apparatus according to the first embodiment, as shown in Figs. 1 and 2, an air guide section 20 for supplying combustion air (Air) is provided on the outer periphery of a fuel supply pipe 10 for supplying a fuel using ammonia (NH3).

[0025] The fuel supply pipe 10 is inserted into a combustion tube 2 that is arranged to pass through the furnace wall 1a of the furnace 1, and a plurality of fuel nozzles 11 are provided circumferentially on the outer periphery of the tip of the fuel supply pipe 10 inserted into the combustion tube 2. A circular flame stabilizing member 12 with a diameter smaller than the inner diameter of the combustion tube 2 is provided on the outer periphery of the fuel supply pipe 10 at a position upstream of the fuel nozzles 11 in the fuel flow direction. The temperature of the flame stabilizing member 12 in the vicinity of the fuel nozzle 11 is detected by a temperature sensor 31 such as a thermocouple, and the temperature of the flame stabilizing member 12 detected by this temperature sensor 31 is output to a control device 30 via a temperature measuring device 32.

[0026] In addition, the combustion air (Air) is guided from the air guide section 20 to the outer periphery of the fuel supply pipe 10 inside the combustion tube 2, and then through the gap (s) between the combustion tube 2 and the flame stabilizing member 12, the combustion air (Air) is guided to the tip of the fuel supply pipe 10, and the fuel ejected from each fuel nozzle 11 provided on the outer periphery of the tip of the fuel supply pipe 10 is mixed with the combustion air (Air) and combusted inside the combustion tube 2.

[0027] Here, in the ammonia combustion apparatus according to the first embodiment, in order to introduce fuel using ammonia NH3 to the fuel nozzle 11 provided at the tip of the fuel supply pipe 10, an ammonia decomposition device 40 for decomposing ammonia NH3 into hydrogen gas H2 and nitrogen gas N2 is provided at a position before the fuel supply pipe 10 is inserted into the combustion tube 2.

[0028] In the ammonia combustion device according to the first embodiment, the ammonia decomposition device 40 is provided with a catalytic reforming section 41 that contains a catalyst that decomposes ammonia NH3 into hydrogen gas H2 and nitrogen gas N2, and a thermal reforming section (heater) 42 that heats the ammonia NH3 introduced into the catalytic reforming section 41 to activate the decomposition action of the ammonia NH3. In the first embodiment, the ammonia decomposition device 40 has both the catalytic reforming section 41 and the thermal reforming section 42 as described above, but since the catalyst has a decomposition action even if it is not activated by heating, and ammonia NH3 decomposes when the heating temperature is increased, it is also possible to use either the catalytic reforming section 41 or the thermal reforming section 42 alone.

[0029] In the ammonia combustion apparatus according to the first embodiment, the fuel supply pipe 10 is provided with a first supply passage 13 for guiding a fuel using ammonia NH3 to the ammonia decomposition device 40 to decompose the ammonia NH3 into hydrogen gas H2 and nitrogen gas N2, and a second supply passage 14 for guiding the fuel to the tip of the fuel supply pipe 10 without passing through the ammonia decomposition device 40. The first supply passage 13 and the second supply passage 14 are provided with flow control valves 13a and 14a, respectively, and the flow control valves 13a and 14a are controlled by the control device 30 to control the amount of the fuel guided to the ammonia decomposition device 40 through the first supply passage 13 and the amount of the fuel flowing through the second supply passage 14 that is not guided to the ammonia decomposition device 40.

[0030] In the ammonia combustion apparatus according to the first embodiment, the fuel ejected from each fuel ejection port 11 provided circumferentially on the outer periphery of the tip of the fuel supply pipe 10 as described above is mixed with the combustion air (Air) guided from the outer periphery of the fuel supply pipe 10 to the tip of the fuel supply pipe 10 through the gap (s) between the combustion tube 2 and the flame stabilizer 12, and combusted in the combustion tube 2. As described above, the temperature of the flame stabilizer 12 in the vicinity of the fuel ejection port 11 is detected by the temperature sensor 31 and output to the control device 30.

[0031] Here, in the ammonia combustion apparatus of this embodiment 1, when the temperature of the flame stabilizing member 12 in the vicinity of the combustion section detected by the temperature sensor 31 is low, such as in the initial stage of starting combustion of fuel using ammonia NH3, it may be difficult to burn the ammonia NH3 fuel as it is, so the control device 30 reduces the opening of the flow control valve 14a provided in the second supply path 14 to reduce the amount of ammonia NH3 flowing through the second supply path 14, while increasing the opening of the flow control valve 13a to increase the amount of ammonia NH3 guided to the ammonia decomposition device 40 through the first supply path 13.

[0032] Then, a large amount of ammonia NH3 introduced to the ammonia decomposition device 40 through the first supply passage 13 is decomposed into hydrogen gas H2 and nitrogen gas N2, and the decomposed hydrogen gas H2 and nitrogen gas N2 are mixed with ammonia NH3 introduced through the second supply passage 14 and introduced through the fuel supply pipe 10 to each fuel nozzle 11 provided at the tip of the fuel supply pipe 10, and the fuel mixed with the hydrogen gas H2, nitrogen gas N2 and ammonia NH3 is ejected from each fuel nozzle 11, and mixed with the combustion air Air introduced to the tip of the fuel supply pipe 10 through the gap s between the combustion tube 2 and the flame stabilizing member 12 as described above, and combusted in the combustion tube 2 toward the furnace 1.

[0033] In this manner, a large amount of ammonia NH3 is decomposed by the ammonia decomposition device 40, and the fuel containing a large amount of highly combustible hydrogen gas H2 is mixed with the combustion air Air and burned. This improves combustibility compared to the case where only ammonia NH3 is mixed with the combustion air Air and burned, and enables stable combustion even when the temperature of the flame stabilizing member 12 is low.

[0034] On the other hand, when the fuel obtained by decomposing ammonia NH3 into hydrogen gas H2 and nitrogen gas N2 as described above is mixed with the combustion air Air and burned, the temperature in the combustion section rises, and there is a risk of damaging the flame stabilizing member 12 or the tip of the fuel supply pipe 10. In this case, the temperature of the flame stabilizing member 12 is detected by the temperature sensor 31, and when the detected temperature of the flame stabilizing member 12 rises to a predetermined temperature, the control device 30 reduces the opening of the flow control valve 13a to reduce the amount of ammonia NH3 led to the ammonia decomposition device 40 through the first supply path 13, thereby reducing the amount of ammonia NH3 decomposed by the ammonia decomposition device 40 into hydrogen gas H2 and nitrogen gas N2. On the other hand, the opening of the flow control valve 14a provided in the second supply path 14 is increased to increase the amount of ammonia NH3 flowing through the second supply path 14, thereby reducing the amount of hydrogen gas H2 contained in the fuel led to each fuel nozzle 11 provided at the tip of the fuel supply pipe 10.

[0035] Then, the fuel with a large amount of ammonia NH3 and a small amount of hydrogen gas H2 is ejected from each fuel nozzle 11 and mixed with the combustion air Air guided to the tip of the fuel supply pipe 10 through the gap s between the combustion tube 2 and the flame stabilizing member 12 as described above, and combusted in the combustion tube 2 toward the furnace 1. This lowers the combustion temperature of the fuel, prevents the temperature in the combustion section from becoming too high, and prevents damage to the flame stabilizing member 12 and the tip of the fuel supply pipe 10.

[0036] In the ammonia combustion apparatus of the first embodiment, in order to control the amount of ammonia NH3 decomposed into hydrogen gas H2 and nitrogen gas N2 by the ammonia decomposition device 40, the fuel supply pipe 10 is provided with a first supply passage 13 for guiding a fuel using ammonia NH3 to the ammonia decomposition device 40 to decompose the ammonia NH3 into hydrogen gas H2 and nitrogen gas N2, and a second supply passage 14 for guiding the fuel to the tip of the fuel supply pipe 10 without passing through the ammonia decomposition device 40, and the openings of the flow control valves 13a, 14a provided on the first supply passage 13 and the second supply passage 14 are adjusted. However, when the amount of ammonia NH3 decomposed into hydrogen gas H2 and nitrogen gas N2 is to be significantly changed, the flow control valve 13a provided on the first supply passage 13 and the flow control valve 14a provided on the second supply passage 14 can be closed.

[0037] In addition, in the ammonia combustion device of this embodiment 1, in order to control the amount of ammonia NH3 decomposed into hydrogen gas H2 and nitrogen gas N2 by the ammonia decomposition device 40, the fuel supply pipe 10 is provided with a first supply passage 13 that guides the fuel using ammonia NH3 to the ammonia decomposition device 40, and a second supply passage 14 that guides the fuel to the tip of the fuel supply pipe 10 without passing through the ammonia decomposition device 40, but this is not limited to the above.

[0038] For example, as shown in FIG. 3, all fuel using ammonia NH3 can be led to an ammonia decomposition device 40 through a fuel supply pipe 10, and the temperature at which the fuel using ammonia NH3 is heated in a thermal reforming section (heater) 42 in the ammonia decomposition device 40 can be simply controlled by the control device 30.

[0039] As described above, when the control device 30 adjusts the temperature at which the fuel using ammonia NH3 is heated in the thermal reforming section 42, if the temperature of the flame stabilizing member 12 in the vicinity of the combustion section detected by the temperature sensor 31 is low, the control device 30 increases the temperature of the thermal reforming section 42 in the ammonia decomposition device 40 to increase the amount of ammonia NH3 in the fuel that is decomposed into hydrogen gas H2 and nitrogen gas N2. On the other hand, if the temperature in the vicinity of the combustion section detected by the temperature sensor 31 increases and there is a risk of damaging the flame stabilizing member 12 or the tip of the fuel supply pipe 10, the control device 30 decreases the temperature of the thermal reforming section 42 in the ammonia decomposition device 40 to reduce the amount of ammonia NH3 in the fuel that is decomposed into hydrogen gas H2 and nitrogen gas N2.

[0040] (Embodiment 2) In the ammonia combustion apparatus of the second embodiment, instead of the combustion tube 2 in the ammonia combustion apparatus of the first embodiment, a radiant tube 3 is provided so as to pass through the furnace wall 1a of the furnace 1 as shown in FIG. 4, and a fuel supply pipe 10 for supplying fuel using ammonia NH3 is inserted into the radiant tube 3.

[0041] In addition, a plurality of fuel nozzles 11 are provided circumferentially on the outer periphery of the tip of the fuel supply pipe 10, and a circular flame-stabilizing member 12 with a diameter smaller than the inner diameter of the radiant tube 3 is provided on the outer periphery of the fuel supply pipe 10 at a position upstream of the fuel nozzles 11 in the fuel flow direction, and the temperature of the flame-stabilizing member 12 in the vicinity of the fuel nozzle 11 is detected by a temperature sensor 31.

[0042] The fuel ejected from each fuel nozzle 11 provided circumferentially on the outer periphery of the tip of the fuel supply pipe 10 is mixed with combustion air Air guided from the outer periphery of the fuel supply pipe 10 through the gap s between the radiant tube 3 and the flame stabilizing member 12 to the tip of the fuel supply pipe 10, and combusted in the radiant tube 3 to indirectly heat the inside of the furnace 1.Other than that, the configuration is the same as that of the ammonia combustion apparatus of the first embodiment.

[0043] Here, in the ammonia combustion apparatus according to the second embodiment, when a fuel using ammonia NH3 is burned in the radiant tube 3 in the same manner as in the ammonia combustion apparatus according to the first embodiment, when the temperature in the vicinity of the combustion section is low, as in the case of the ammonia combustion apparatus according to the first embodiment, the control device 30 causes the ammonia decomposition device 40 to decompose a large amount of ammonia NH3 into hydrogen gas H2 and nitrogen gas N2, so that the fuel containing a large amount of highly combustible hydrogen gas H2 is mixed with the combustion air Air and burned, and the combustibility is improved compared to the case where only ammonia NH3 is mixed with the combustion air Air and burned, and stable combustion can be performed.

[0044] On the other hand, if there is a risk that the temperature in the combustion section will rise and damage the flame-stabilizing member 12 or the tip of the fuel supply pipe 10 will occur, the control device 30 will reduce the amount of ammonia NH3 decomposed by the ammonia decomposition device 40 into hydrogen gas H2 and nitrogen gas N2, and reduce the amount of hydrogen gas H2 contained in the fuel before combustion, thereby preventing the temperature in the combustion section from becoming too high and preventing damage to the flame-stabilizing member 12 or the tip of the fuel supply pipe 10. [Explanation of symbols]

[0045] 1: Furnace 1a: Furnace wall 2: Combustion tube 3: Radiant tube 10:Fuel supply pipe 11:Fuel spout 12: Flame retaining material 13: 1st supply route 13a: Flow control valve 14:Second supply route 14a: Flow control valve 20: Air guide section 30: Control device 31: Temperature sensor (thermocouple) 32: Temperature measuring device 40: Ammonia decomposition unit 41: Catalytic reforming section 42: Heating reforming section (heater) Air: Combustion air H2: Hydrogen gas N2: Nitrogen gas NH3: Ammonia s: gap

Claims

1. An ammonia combustion apparatus having a fuel supply pipe at a tip end thereof for supplying ammonia-based fuel with a fuel outlet for ejecting the fuel, and having the fuel ejected from the fuel outlet mixed with combustion air introduced from the outer periphery of the fuel supply pipe and combusted in a combustion section, the ammonia combustion apparatus further comprising an ammonia decomposer for decomposing ammonia into hydrogen gas and nitrogen gas in the fuel supply pipe, a temperature sensor for detecting a temperature in the vicinity of the combustion section where the fuel and combustion air are mixed and combusted, and a control device for controlling the ammonia decomposer based on the temperature detected by the temperature sensor, the control device increasing the amount of ammonia decomposed into hydrogen gas and nitrogen gas by the ammonia decomposer when the temperature detected by the temperature sensor is low, and decreasing the amount of ammonia decomposed into hydrogen gas and nitrogen gas by the ammonia decomposer when the temperature detected by the temperature sensor is high.

2. 2. The ammonia combustion apparatus according to claim 1, wherein the ammonia decomposition device is provided with at least one of a catalytic reforming section containing a catalyst for decomposing ammonia into hydrogen gas and nitrogen gas, and a thermal reforming section for heating ammonia to decompose it into hydrogen gas and nitrogen gas.

3. 3. The ammonia combustion apparatus according to claim 2, wherein at least the thermal reforming section is provided in the ammonia decomposition device, and the control device changes the temperature at which the ammonia is heated in the thermal reforming section when controlling the amount of ammonia decomposed into hydrogen gas and nitrogen gas by the ammonia decomposition device.

4. 2. The ammonia combustion apparatus according to claim 1, wherein, when the fuel supply pipe guides the ammonia-based fuel to a fuel outlet provided at a tip of the fuel supply pipe, a first supply path that guides the ammonia-based fuel through the ammonia decomposer and a second supply path that guides the ammonia-based fuel without passing through the ammonia decomposer are provided, and when the temperature detected by the temperature sensor is low, the control device increases the amount of the ammonia-based fuel guided to the first supply path to increase the amount of ammonia decomposed into hydrogen gas and nitrogen gas by the ammonia decomposer, while when the temperature detected by the temperature sensor is high, the control device increases the amount of the ammonia-based fuel guided to the second supply path to decrease the amount of ammonia decomposed into hydrogen gas and nitrogen gas by the ammonia decomposer.

5. 5. The ammonia combustion apparatus according to claim 1, further comprising: a flame stabilizing member provided on an outer circumferential side of the fuel supply pipe upstream of a fuel outlet at a tip of the fuel supply pipe in a fuel flow direction; and the temperature sensor provided in the vicinity of the flame stabilizing member.

6. An ammonia combustion apparatus comprising: an ammonia combustion apparatus according to any one of claims 1 to 4 provided in a radiant tube.

7. 6. An ammonia combustion apparatus comprising: the ammonia combustion apparatus according to claim 5 provided in a radiant tube.

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