Ammonia combustion equipment

Abstract

To efficiently remove unburned ammonia included in exhaust gas after ammonia is burned in a combustion furnace.SOLUTION: A first combustion furnace 10 includes a first combustion burner 11 for burning ammonia NH3. A second combustion furnace 20 to which first exhaust gas Ga1 including unburned ammonia discharged from the first combustion furnace is guided includes a second combustion burner 21 for mixing and burning fuel G and air Air. An ammonia combustion facility includes: a first guide passage 15 for guiding first exhaust gas including unburned ammonia discharged from the first combustion furnace into the second combustion furnace; and a second guide passage 16 for guiding the first exhaust gas to the second combustion burner provided in the second combustion furnace. An amount of the first exhaust gas containing the unburned ammonia to be guided to the first guide passage and the second guide passage is controlled by control means 30.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to ammonia combustion equipment for combusting ammonia. The invention is particularly characterized in that it is capable of sufficiently removing unburned ammonia contained in exhaust gas after ammonia is combusted in a combustion furnace. [Background Art]

[0002] In combustion equipment that mixes fuel with combustion air and combusts the mixture, equipment using hydrocarbon-based fuel as fuel is generally employed.

[0003] However, such combustion apparatuses that mix and combust hydrocarbon-based fuel with combustion air have had the problem of generating large amounts of greenhouse gases such as carbon dioxide.

[0004] For this reason, in recent years, the use of fuels other than hydrocarbon-based fuels has been studied.

[0005] Furthermore, the use of ammonia as a fuel has been implemented. However, ammonia has poorer combustibility than hydrocarbon-based fuels, making complete combustion difficult, and thus has the problem that unburned ammonia remains in the exhaust gas after combustion.

[0006] Regarding the combustion of ammonia, which has poor combustibility, Patent Document 1 discloses combustion equipment including a boiler that has a burner for combusting ammonia and co-combusts ammonia with pulverized coal, and a denitration device that denitrates exhaust gas discharged from the boiler, wherein the combustion equipment is provided with a combustion state determination system that determines the combustion state of ammonia in the boiler.

[0007] However, Patent Document 1 only shows that a denitrification device is provided to denitrify the exhaust gas discharged from the boiler, and that the combustion state of ammonia in the boiler is determined by a combustion state determination system. It does not show at all how to treat the unburned ammonia contained in the exhaust gas after ammonia has been burned.

[0008] Furthermore, Patent Document 2 proposes a method in which ammonia is added to a burner that burns fossil fuels, and the ammonia is burned together with the fossil fuels to suppress the generation of unburned ammonia.

[0009] However, Patent Document 2 only shows that burning ammonia together with fossil fuels suppresses the generation of unburned ammonia, and does not show at all how to deal with the unburned ammonia that remains after burning. [Prior art documents] [Patent Documents]

[0010] [Patent Document 1] WO2019 / 092858 publication [Patent Document 2] Japanese Patent Publication No. 2018-76985 [Disclosure of the Invention] [Problems that the invention aims to solve]

[0011] The present invention aims to solve problems in ammonia combustion equipment that burns ammonia, and in particular, to enable sufficient removal of unburned ammonia contained in the exhaust gas after ammonia has been burned in a combustion furnace. [Means for solving the problem]

[0012] In the ammonia combustion equipment according to the present invention, in order to solve the above-mentioned problems, a first combustion furnace equipped with a first combustion burner for burning ammonia, and a second combustion furnace into which a first exhaust gas containing unburned ammonia discharged from the first combustion furnace is introduced, a second combustion burner for mixing fuel and air and burning it is provided in the second combustion furnace, a first guide path for guiding the first exhaust gas containing the unburned ammonia discharged from the first combustion furnace into the second combustion furnace, and a second guide path for guiding it to the second combustion burner provided in the second combustion furnace, and the first guide path and the second guide path are provided A control means is provided to control the amount of the first exhaust gas containing the unburned ammonia. When the amount of unburned ammonia in the first exhaust gas is small, the control means increases the amount of the first exhaust gas guided into the second combustion furnace through the first guide passage, thereby guiding the unburned ammonia into the second combustion furnace for combustion. Conversely, when the amount of unburned ammonia in the first exhaust gas is large, the control means increases the amount of the first exhaust gas guided to the second combustion burner through the second guide passage, thereby increasing the amount of unburned ammonia burned together with the fuel.

[0013] Furthermore, in the ammonia combustion equipment according to the present invention, when the amount of unburned ammonia contained in the first exhaust gas discharged from the first combustion furnace is small, simply increasing the amount of the first exhaust gas guided into the second combustion furnace through the first guide passage and burning the unburned ammonia in the second combustion furnace will ensure that the unburned ammonia contained in the first exhaust gas is sufficiently burned and removed in the second combustion furnace. Also, when the amount of unburned ammonia contained in the first exhaust gas discharged from the first combustion furnace is large, the first exhaust gas is guided to the second combustion burner installed in the second combustion furnace through the second guide passage, and the unburned ammonia is burned together with the fuel in the second combustion burner. As a result, even if the first exhaust gas contains a large amount of unburned ammonia, it will be burned together with the fuel and sufficiently removed.

[0014] In the ammonia combustion equipment according to the present invention, it is preferable to increase the diameter of the second guide passage to reduce the flow velocity of the first exhaust gas guided to the second combustion burner through the second guide passage. In this way, the first exhaust gas, which contains a large amount of unburned ammonia, is mixed more uniformly with the fuel supplied to the second combustion burner and burned, thereby ensuring more reliable combustion of the unburned ammonia.

[0015] Furthermore, in the ammonia combustion equipment according to the present invention, an ammonia concentration detection device is provided to detect the concentration of unburned ammonia contained in the first exhaust gas discharged from the first combustion furnace. Based on the concentration of unburned ammonia detected by the ammonia concentration detection device, the control means can control the amount of the first exhaust gas containing the unburned ammonia that is guided to the first guide path and the second guide path. In this way, when the amount of unburned ammonia contained in the first exhaust gas is small, the amount of the first exhaust gas guided into the second combustion furnace through the first guide path is increased to guide the unburned ammonia into the second combustion furnace and burn it. On the other hand, when the amount of unburned ammonia contained in the first exhaust gas is large, the first exhaust gas is guided to the second combustion burner installed in the second combustion furnace through the second guide path, and the unburned ammonia is burned together with the fuel in the second combustion burner. This can be easily controlled.

[0016] In the ammonia combustion equipment according to the present invention, if the combustion in the first combustion burner misfires and the amount of unburned ammonia contained in the first exhaust gas discharged from the first combustion furnace increases significantly, the control means can stop guiding the first exhaust gas into the second combustion furnace through the first guide passage, and guide the first exhaust gas to the second combustion burner through the second guide passage to burn the unburned ammonia together with the fuel. In this way, even if the combustion of ammonia in the first combustion burner misfires and the amount of unburned ammonia contained in the first exhaust gas discharged from the first combustion furnace increases significantly, the first exhaust gas containing a large amount of unburned ammonia is guided to the second combustion burner, and in the second combustion burner, the unburned ammonia is burned together with the fuel and sufficiently removed. [Effects of the Invention]

[0017] In the ammonia combustion equipment of the present invention, when the amount of unburned ammonia contained in the first exhaust gas discharged from the first combustion furnace is small, the amount of the first exhaust gas guided into the second combustion furnace through the first guide passage is increased so that the unburned ammonia is guided into the second combustion furnace and burned. On the other hand, when the amount of unburned ammonia contained in the first exhaust gas discharged from the first combustion furnace is large, the first exhaust gas is guided into the second combustion burner provided in the second combustion furnace through the second guide passage so that the unburned ammonia is burned together with the fuel in the second combustion burner.

[0018] As a result, in the ammonia combustion equipment according to the present invention, when the amount of unburned ammonia contained in the first exhaust gas is small, the first exhaust gas is guided into the second combustion furnace, where the unburned ammonia is burned in the second combustion furnace and is sufficiently removed. On the other hand, when the amount of unburned ammonia contained in the first exhaust gas is large, the first exhaust gas is guided to the second combustion burner provided in the second combustion furnace, where the unburned ammonia is burned together with the fuel in the second combustion burner and is sufficiently removed, thereby reliably preventing the discharge of unburned ammonia from the second combustion furnace to the outside. [Brief explanation of the drawing]

[0019] [Figure 1] This is a schematic diagram illustrating an ammonia combustion equipment according to an embodiment of the present invention, in which ammonia is burned by a first combustion burner in a first combustion furnace, and the amount of first exhaust gas guided to the second combustion furnace through a first guide path and a second guide path is controlled by a control means according to the amount of unburned ammonia contained in the first exhaust gas after combustion. [Figure 2] This is a schematic diagram illustrating a state in the ammonia combustion equipment according to the above embodiment in which, when the combustion of ammonia by the first combustion burner in the first combustion furnace fails, the first exhaust gas containing a large amount of unburned ammonia is guided through the second guide passage to the second combustion burner in the second combustion furnace, and the unburned ammonia is burned together with the fuel in the second combustion burner. [Figure 3] This is a schematic diagram illustrating a modified example 1 of the ammonia combustion equipment according to the above embodiment, in which the diameter of the second guide passage that guides the first exhaust gas containing a large amount of unburned ammonia to the second combustion burner in the second combustion furnace when the combustion of ammonia by the first combustion burner in the first combustion furnace fails has been increased. [Figure 4]In Modified Example 2 of the ammonia combustion facility according to the above embodiment, an ammonia concentration detector that detects the concentration of unburned ammonia contained in the first exhaust gas discharged from the first combustion furnace is provided, and this schematic explanatory diagram shows a state where, based on the concentration of unburned ammonia detected by the ammonia concentration detector, a control means controls the amount of the first exhaust gas containing unburned ammonia that is guided to the first guide path and the second guide path. Best Mode for Carrying Out the Invention

[0020] Hereinafter, an ammonia combustion facility according to an embodiment of the present invention will be specifically described with reference to the accompanying drawings. The ammonia combustion facility according to the present invention is not limited to those shown in the following embodiments, and can be appropriately modified and implemented without changing the gist of the invention.

[0021] In the ammonia combustion facility according to this embodiment, as shown in FIG. 1, the amount of ammonia NH3 supplied to a first combustion burner 11 provided in a first combustion furnace 10 that heats an object to be heated (not shown) is controlled by a flow rate control valve 12a provided in a fuel supply pipe 12, and the amount of air Air supplied to the first combustion burner 11 is controlled by a flow rate control valve 13a provided in an air supply pipe 13. The ammonia NH3 is mixed with air Air, combusted in the first combustion furnace 10 by the first combustion burner 11, and the first exhaust gas Ga1 after combustion is guided to a second combustion furnace 20 through a first exhaust gas path 14, so that unburned ammonia NH3 is combusted.

[0022] In the ammonia combustion facility according to this embodiment, a flame sensor 17 detects the combustion state in the first combustion furnace 10, and outputs the detection result obtained by the flame sensor 17 to a control means 30.

[0023] Here, when ammonia NH3 is mixed with air as described above and burned in the first combustion furnace 10 by the first combustion burner 11, the ammonia NH3 is not completely burned, and unburned ammonia NH3 remains in the first exhaust gas Ga1.

[0024] Furthermore, when guiding the first exhaust gas Ga1, which contains unburned ammonia NH3, to the second combustion furnace 20 through the first exhaust gas passage 14 as described above, a first guide passage 15 is provided to guide the first exhaust gas Ga1 directly into the second combustion furnace 20, and a second guide passage 16 is provided to guide the first exhaust gas Ga1 to the second combustion burner 21 installed in the second combustion furnace 20. The control means 30 controls the flow control valve 15a installed in the first guide passage 15 and the flow control valve 16a installed in the second guide passage 16 to control the amount of first exhaust gas Ga1 guided to the second combustion furnace 20 through the first guide passage 15 and the amount of first exhaust gas Ga1 guided to the second combustion burner 21 installed in the second combustion furnace 20 through the second guide passage 16.

[0025] Here, in the second combustion burner 21 installed in the second combustion furnace 20, the amount of fuel G supplied is controlled by a flow control valve 22a installed in the fuel supply pipe 22, and the amount of air supplied is controlled by a flow control valve 23a installed in the air supply pipe 23, so that the fuel G is mixed with the air and burned. Furthermore, the first exhaust gas Ga1, which is adjusted by the flow control valve 16a and guided through the second guide passage 16, is supplied to the air supply pipe 23. It is also possible to supply the first exhaust gas Ga1, which is adjusted by the flow control valve 16a and guided through the second guide passage 16, to the fuel supply pipe 22.

[0026] Furthermore, when the amount of unburned ammonia NH3 contained in the first exhaust gas Ga1 is small, the control means 30 reduces the amount of first exhaust gas Ga1 guided to the second combustion burner 21 through the second guide passage 16, and increases the amount of first exhaust gas Ga1 guided into the second combustion furnace 20 through the first guide passage 15. Even if the unburned ammonia NH3 contained in the first exhaust gas Ga1 is sufficiently burned in the second combustion furnace 20, the second exhaust gas Ga2 is discharged through the second exhaust gas passage 24 in the second combustion furnace 20 without containing unburned ammonia NH3. At this time, the flow control valve 16a may be closed to prevent the first exhaust gas Ga1 from being guided into the second guide passage 16.

[0027] On the other hand, when the amount of unburned ammonia NH3 contained in the first exhaust gas Ga1 is large, the control means 30 increases the amount of first exhaust gas Ga1 supplied to the air supply pipe 23 of the second combustion burner 21 through the second guide passage 16, and this first exhaust gas Ga1 is mixed with air through the air supply pipe 23 and with fuel G supplied through the fuel supply pipe 22, and burned in the second combustion furnace 20 by the second combustion burner 21.

[0028] In this way, even if the first exhaust gas Ga1 contains a large amount of unburned ammonia NH3, the unburned ammonia NH3 is mixed with the fuel G together with the air and is thoroughly burned in the second combustion furnace 20, so that the second exhaust gas Ga2 does not contain any unburned ammonia NH3 and is discharged through the second exhaust gas passage 24 in the second combustion furnace 20.

[0029] Furthermore, if the combustion of ammonia NH3 in the first combustion burner 11 fails, the ammonia NH3 will not be burned and will be guided directly to the first exhaust gas passage 14 as the first exhaust gas Ga1. As a result, the amount of unburned ammonia NH3 in the first exhaust gas Ga1 will become very large. Therefore, as shown in Figure 2, when the flame sensor 17 detects that the combustion of ammonia NH3 has failed and outputs this to the control means 30, the control means 30 will close the flow control valve 12a provided in the fuel supply pipe 12 to prevent ammonia NH3 from being supplied to the first combustion furnace 10, and will also close the flow control valve 15a provided in the first guide passage 15 to allow all of the first exhaust gas Ga1, which now contains a very large amount of unburned ammonia NH3, to be supplied to the air supply pipe 23 of the second combustion burner 21 through the second guide passage 16.

[0030] In this way, even if the amount of unburned ammonia NH3 contained in the first exhaust gas Ga1 becomes very large, the first exhaust gas Ga1 mixes with air through the air supply pipe 23 and with fuel G supplied through the fuel supply pipe 22, and is burned in the second combustion furnace 20 by the second combustion burner 21, so that the unburned ammonia NH3 is sufficiently burned in the second combustion furnace 20 and the second exhaust gas Ga2 is discharged through the second exhaust gas passage 24 in the second combustion furnace 20 without containing any unburned ammonia NH3. In addition, even if the combustion of ammonia NH3 in the first combustion burner 11 misfires, it is also possible to slightly open the flow control valve 15a provided in the first guide passage 15 to guide a portion of the first exhaust gas Ga1 into the second combustion furnace 20 through the first guide passage 15. Note that the flow control valves 12a, 13a, 15a, 16a, 22a, and 23a are shown open in white and closed in black.

[0031] Furthermore, as described above, if the combustion of ammonia NH3 in the first combustion burner 11 fails, the first exhaust gas Ga1, which contains a very large amount of unburned ammonia NH3, is supplied entirely through the second guide passage 16 to the air supply pipe 23 of the second combustion burner 21. In order to mix it with the fuel G supplied through the fuel supply pipe 22 and burn it, as shown in Figure 3, the diameter of the second guide passage 16 can be increased to reduce the flow velocity of the first exhaust gas Ga1 guided to the second combustion burner 21 through the second guide passage 16. In this way, by increasing the diameter of the second guide passage 16 and reducing the flow velocity of the first exhaust gas Ga1 guided to the second combustion burner 21 through the second guide passage 16, the first exhaust gas Ga1, which contains a large amount of unburned ammonia NH3, is mixed more uniformly with the fuel G supplied to the second combustion burner 21 and burned, so that the unburned ammonia NH3 is more reliably and sufficiently burned in the second combustion furnace 20, and the second exhaust gas Ga2, which does not contain unburned ammonia NH3, is discharged through the second exhaust gas passage 24 in the second combustion furnace 20.

[0032] Furthermore, when mixing ammonia NH3 with air as described above and burning it in the first combustion furnace 10 by the first combustion burner 11, and guiding the first exhaust gas Ga1 containing unburned ammonia NH3 to the second combustion furnace 20 through the first exhaust gas passage 14 as described above, the control means 30 controls the flow control valve 15a provided in the first guide passage 15 and the flow control valve 16a provided in the second guide passage 16 to control the amount of first exhaust gas Ga1 guided to the second combustion furnace 20 through the first guide passage 15 and the amount of first exhaust gas Ga1 guided to the second combustion burner 21 provided in the second combustion furnace 20 through the second guide passage 16, as shown in Figure 4, an ammonia concentration detection device 18 is provided to detect the concentration of unburned ammonia NH3 contained in the first exhaust gas Ga1 guided to the first exhaust gas passage 14, and the results detected by the ammonia concentration detection device 18 are output to the control means 30.

[0033] If the concentration of unburned ammonia NH3 in the first exhaust gas Ga1 detected by the ammonia concentration detection device 18 is low, the control means 30 reduces the amount of first exhaust gas Ga1 guided to the second combustion burner 21 through the second guide passage 16 and increases the amount of first exhaust gas Ga1 guided into the second combustion furnace 20 through the first guide passage 15, so that the unburned ammonia NH3 in the first exhaust gas Ga1 is burned in the second combustion furnace 20. On the other hand, if the concentration of unburned ammonia NH3 in the first exhaust gas Ga1 detected by the ammonia concentration detection device 18 is high, the amount of first exhaust gas Ga1 supplied to the air supply pipe 23 in the second combustion burner 21 through the second guide passage 16 is increased, and this first exhaust gas Ga1 is mixed with air through the air supply pipe 23 and with fuel G supplied through the fuel supply pipe 22, so that it is burned in the second combustion furnace 20 by the second combustion burner 21.

[0034] In this way, whether the concentration of unburned ammonia NH3 in the first exhaust gas Ga1 is low or high, the second exhaust gas Ga2 can be discharged through the second exhaust gas passage 24 in the second combustion furnace 20 without containing unburned ammonia NH3, just as in the case described above. [Explanation of Symbols]

[0035] 10: First Combustion Reactor 11: First combustion burner 12:Fuel supply pipe 12a: Flow control valve 13: Air supply pipe 13a: Flow control valve 14: First exhaust gas passage 15: First Guideway 15a: Flow control valve 16: Second Guideway 16a: Flow control valve 17: Flame sensor 18: Ammonia concentration detection device 20: Second Combustion Reactor 21: Second combustion burner 22:Fuel supply pipe 22a: Flow control valve 23: Air supply pipe 23a: Flow control valve 24: Second exhaust gas passage 30: Control means Air: air G: fuel Ga1: First exhaust gas Ga2: Second exhaust gas NH3: Ammonia

Claims

1. The invention comprises a first combustion furnace equipped with a first combustion burner for burning ammonia, and a second combustion furnace into which a first exhaust gas containing unburned ammonia discharged from the first combustion furnace is introduced, the second combustion furnace is provided with a second combustion burner for mixing and burning fuel and air, a first guide passage for guiding the first exhaust gas containing the unburned ammonia discharged from the first combustion furnace into the second combustion furnace, and a second guide passage for guiding it to the second combustion burner provided in the second combustion furnace, and the amount of the first exhaust gas containing the unburned ammonia guided to the first guide passage and the second guide passage An ammonia combustion system is provided with a control means to control the amount of unburned ammonia contained in the first exhaust gas, and when the amount of unburned ammonia contained in the first exhaust gas is small, the control means increases the amount of the first exhaust gas guided through the first guide passage into the second combustion furnace to guide the unburned ammonia into the second combustion furnace and burn it, while when the amount of unburned ammonia contained in the first exhaust gas is large, the control means increases the amount of the first exhaust gas guided through the second guide passage to the second combustion burner to increase the amount of unburned ammonia burned together with the fuel.

2. An ammonia combustion apparatus according to claim 1, characterized in that the diameter of the second guide passage is increased to reduce the flow velocity of the first exhaust gas guided to the second combustion burner through the second guide passage.

3. An ammonia combustion facility according to claim 1 or claim 2, characterized in that an ammonia concentration detection device is provided for detecting the concentration of unburned ammonia contained in the first exhaust gas discharged from the first combustion furnace, and the control means controls the amount of the first exhaust gas containing the unburned ammonia that is guided to the first guide path and the second guide path based on the concentration of unburned ammonia detected by the ammonia concentration detection device.

4. An ammonia combustion apparatus according to claim 1 or claim 2, characterized in that, when combustion in the first combustion burner misfires and the amount of unburned ammonia contained in the first exhaust gas discharged from the first combustion furnace increases significantly, the control means stops guiding the first exhaust gas through the first guide passage into the second combustion furnace, and guides the first exhaust gas through the second guide passage to the second combustion burner to burn the unburned ammonia together with the fuel.

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