Ammonia combustion facility

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 an ammonia combustion facility for burning ammonia. In particular, the present invention is characterized in that unburned ammonia contained in exhaust gas after ammonia is burned in a combustion furnace can be sufficiently removed. [Background technology]

[0002] 2. Description of the Related Art In combustion facilities in which fuel is mixed with combustion air and combusted, generally, hydrocarbon fuels are used as the fuel.

[0003] However, such combustion devices that mix hydrocarbon fuel with combustion air and burn it have 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 fuels has been considered.

[0005] In addition, ammonia has been used as a fuel. However, ammonia has poor combustibility compared to hydrocarbon fuels, and it is difficult to completely combust ammonia, and there has been a problem in that unburned ammonia is contained in exhaust gas after combustion.

[0006] In order to combust ammonia, which has poor combustibility, Patent Document 1 discloses a combustion facility including a boiler having a burner for burning ammonia and co-firing the ammonia with pulverized coal, and a denitrification device for denitrifying exhaust gas discharged from the boiler, and the combustion state determination system is provided to determine the combustion state of the ammonia in the boiler.

[0007] However, Patent Document 1 only discloses that a denitration device is provided for denitrifying exhaust gas discharged from a boiler, and that the combustion state of ammonia in the boiler is determined by a combustion state determination system, and does not disclose at all how to treat unburned ammonia contained in the exhaust gas after ammonia is combusted.

[0008] Furthermore, Patent Document 2 proposes adding ammonia to a burner that burns fossil fuels, and burning the ammonia together with the fossil fuels to suppress the generation of unburned ammonia.

[0009] However, Patent Document 2 only discloses that ammonia is burned together with fossil fuel to suppress the generation of unburned ammonia, and does not disclose at all how to treat the unburned ammonia that remains unburned when ammonia is burned. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] WO2019 / 092858 publication [Patent Document 2] JP 2018-76985 A DISCLOSURE OF THEINVENTION [Problem to be solved by the invention]

[0011] An object of the present invention is to solve problems in ammonia combustion facilities that combust ammonia, and in particular to make it possible to sufficiently remove unburned ammonia contained in exhaust gas after ammonia is combusted in a combustion furnace. [Means for solving the problem]

[0012] In order to solve the above-mentioned problems, the ammonia combustion equipment according to the present invention has a first combustion furnace equipped with a first combustion burner for burning ammonia, and a second combustion furnace to which a first exhaust gas containing unburned ammonia discharged from the first combustion furnace is guided, the second combustion furnace is provided with a second combustion burner for mixing fuel and air and burning the resulting mixture, a first guide path is provided for guiding the first exhaust gas containing unburned ammonia discharged from the first combustion furnace into the second combustion furnace, and a second guide path is provided for guiding the first exhaust gas containing unburned ammonia discharged from the first combustion furnace to the second combustion burner provided in the second combustion furnace, and a gas guided between the first guide path and the second guide path is provided. A control means is provided for controlling the amount of the first exhaust gas containing the unburned ammonia, 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 introduced into the second combustion furnace through the first guide path, so that the unburned ammonia is introduced into the second combustion furnace and burned therein, 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 introduced into the second combustion burner through the second guide path, so that the amount of unburned ammonia to be burned together with the fuel is increased.

[0013] In the ammonia combustion facility 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, the amount of the first exhaust gas introduced into the second combustion furnace through the first guide path is increased, and the unburned ammonia is introduced into the second combustion furnace and burned therein, so that the unburned ammonia contained in the first exhaust gas is sufficiently burned and removed in the second combustion furnace. In addition, 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 introduced into the second combustion burner provided 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, so that even if the first exhaust gas contains a large amount of unburned ammonia, it is 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 and 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 containing a large amount of unburned ammonia is more uniformly mixed with the fuel supplied to the second combustion burner and burned, so that the unburned ammonia can be more reliably burned.

[0015] In the ammonia combustion facility according to the present invention, an ammonia concentration detector is provided for detecting the concentration of unburned ammonia contained in the first exhaust gas discharged from the first combustion furnace, and the amount of the first exhaust gas containing unburned ammonia introduced into the first guide path and the second guide path can be controlled by the control means based on the concentration of unburned ammonia detected by the ammonia concentration detector. In this way, when the amount of unburned ammonia contained in the first exhaust gas is small as described above, the amount of the first exhaust gas introduced into the second combustion furnace through the first guide path is increased so that the unburned ammonia is introduced into the second combustion furnace and burned therein, while when the amount of unburned ammonia contained in the first exhaust gas is large, the first exhaust gas is introduced into the second combustion burner provided 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.

[0016] Here, in the ammonia combustion equipment according to the present invention, 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 can stop guiding the first exhaust gas through the first guide path into the second combustion furnace, and guide the first exhaust gas through the second guide path to the second combustion burner to burn the unburned ammonia together with the fuel. In this way, even when 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 the unburned ammonia is combusted together with the fuel in the second combustion burner and sufficiently removed. Effect 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 as described above, the amount of the first exhaust gas guided into the second combustion furnace through the first guide path is increased so that the unburned ammonia is guided into the second combustion furnace and burned, whereas 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 through the second guide path to a second combustion burner provided in the second combustion furnace, and the unburned ammonia is burned together with the fuel in the second combustion burner.

[0018] As a result, in the ammonia combustion equipment of the present invention, when the amount of unburned ammonia contained in the first exhaust gas is small, the first exhaust gas is led into the second combustion furnace, and the unburned ammonia is burned in the second combustion furnace, so that the unburned ammonia is sufficiently removed, whereas when the amount of unburned ammonia contained in the first exhaust gas is large, the first exhaust gas is led to a second combustion burner provided in the second combustion furnace, and the unburned ammonia is burned together with the fuel in the second combustion burner, so that the unburned ammonia is sufficiently removed, thereby making it possible to reliably prevent unburned ammonia from being discharged to the outside from the second combustion furnace. [Brief description of the drawings]

[0019] [Figure 1] FIG. 1 is a schematic explanatory diagram showing a state in which ammonia is burned by a first combustion burner in a first combustion furnace, and the amount of the first exhaust gas guided to a 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 a first exhaust gas after combustion, in an ammonia combustion facility according to an embodiment of the present invention. [Diagram 2] FIG. 1 is a schematic explanatory diagram showing a state in which, in the ammonia combustion equipment according to the embodiment, when combustion of ammonia by a first combustion burner in a first combustion furnace goes awry, a first exhaust gas containing a large amount of unburned ammonia is guided through a second guide path to a second combustion burner in a second combustion furnace, and the unburned ammonia is burned together with fuel in the second combustion burner. [Diagram 3] FIG. 11 is a schematic explanatory diagram showing a state 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 is increased when combustion of ammonia by the first combustion burner in the first combustion furnace misfires in a first modification of the ammonia combustion equipment according to the above embodiment. [Figure 4]FIG. 11 is a schematic explanatory diagram showing a state in which 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 in a modified example 2 of the ammonia combustion equipment according to the embodiment, and the amount of the first exhaust gas containing unburned ammonia that is guided to the first guide path and the second guide path is controlled by a control means based on the concentration of unburned ammonia detected by the ammonia concentration detection device. BEST MODE FOR CARRYING OUT THEINVENTION

[0020] Hereinafter, an ammonia combustion facility according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. Note that the ammonia combustion facility 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.

[0021] In the ammonia combustion equipment according to this embodiment, as shown in FIG. 1, the amount of ammonia NH3 supplied to the first combustion burner 11 provided in the first combustion furnace 10 for heating the object to be heated (not shown) is controlled by a flow control valve 12a provided in the fuel supply pipe 12, and the amount of air Air supplied to the first combustion burner 11 is controlled by a flow control valve 13a provided in the air supply pipe 13, and the ammonia NH3 is mixed with the air Air and burned in the first combustion furnace 10 by the first combustion burner 11, and the first exhaust gas Ga1 after combustion is led to the second combustion furnace 20 through the first exhaust gas passage 14 to burn the unburned ammonia NH3.

[0022] In the ammonia combustion facility according to this embodiment, the combustion state in the first combustion furnace 10 is detected by a flame sensor 17, and the detection result by the flame sensor 17 is output 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] When the first exhaust gas Ga1 containing unburned ammonia NH3 is guided to the second combustion furnace 20 through the first exhaust gas passage 14 as described above, a first guide passage 15 is provided for guiding the first exhaust gas Ga1 directly into the second combustion furnace 20, and a second guide passage 16 is provided for guiding the first exhaust gas Ga1 to a second combustion burner 21 provided in the second combustion furnace 20. 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 the first exhaust gas Ga1 guided to the second combustion furnace 20 through the first guide passage 15 and the amount of the first exhaust gas Ga1 guided to the second combustion furnace 20 through the second guide passage 16.

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

[0026] In a state where the amount of unburned ammonia NH3 contained in the first exhaust gas Ga1 is small, the amount of the first exhaust gas Ga1 guided to the second combustion burner 21 through the second guide passage 16 is reduced by the control means 30, and even if the amount of the first exhaust gas Ga1 guided to the second combustion furnace 20 through the first guide passage 15 is increased, the unburned ammonia NH3 contained in the first exhaust gas Ga1 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 unburned ammonia NH3. At this time, the flow control valve 16a may be closed so that the first exhaust gas Ga1 is not guided to 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 the first exhaust gas Ga1 supplied to the air supply pipe 23 in the second combustion burner 21 through the second guide passage 16, and this first exhaust gas Ga1 is mixed with air Air through the air supply pipe 23 and mixed with the fuel G supplied through the fuel supply pipe 22, and combusted in the second combustion furnace 20 by the second combustion burner 21.

[0028] In this manner, 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 Air and is sufficiently combusted 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 unburned ammonia NH3.

[0029] In addition, if the combustion of ammonia NH3 in the first combustion burner 11 misfires, the ammonia NH3 is not burned and is introduced as it is into the first exhaust gas passage 14 as the first exhaust gas Ga1, and the amount of unburned ammonia NH3 in the first exhaust gas Ga1 becomes very large. Therefore, when the misfire of the combustion of ammonia NH3 is detected by the flame sensor 17 and output to the control means 30 as shown in FIG. 2, the control means 30 closes 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 closes the flow control valve 15a provided in the first guide passage 15 to supply all of the first exhaust gas Ga1 with a very large amount of unburned ammonia NH3 through the second guide passage 16 to the air supply pipe 23 in the second combustion burner 21.

[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 is mixed with the air Air through the air supply pipe 23 and mixed with the fuel G supplied through the fuel supply pipe 22, and is burned in the second combustion furnace 20 by the second combustion burner 21, and 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 unburned ammonia NH3. Even if the combustion of ammonia NH3 in the first combustion burner 11 fails in this way, it is also possible to slightly open the flow control valve 15a provided in the first guide passage 15 to guide a part of the first exhaust gas Ga1 into the second combustion furnace 20 through the first guide passage 15. The flow control valves 12a, 13a, 15a, 16a, 22a, and 23a are shown as open in white and closed in black.

[0031] Furthermore, in the case where the combustion of ammonia NH3 in the first combustion burner 11 misfires as described above, the first exhaust gas Ga1 with a very large amount of unburned ammonia NH3 is supplied entirely through the second guide passage 16 to the air supply pipe 23 in the second combustion burner 21, and mixed with the fuel G supplied through the fuel supply pipe 22 for combustion, the diameter of the second guide passage 16 can be increased as shown in FIG. 3 to reduce the flow rate 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 rate of the first exhaust gas Ga1 guided through the second guide passage 16 to the second combustion burner 21, the first exhaust gas Ga1 containing a large amount of unburned ammonia NH3 is more uniformly mixed with the fuel G supplied to the second combustion burner 21 and burned, so that the unburned ammonia NH3 is more reliably combusted sufficiently within the second combustion furnace 20, and the second exhaust gas Ga2 not containing unburned ammonia NH3 is discharged through the second exhaust gas passage 24 in the second combustion furnace 20.

[0032] In addition, when the ammonia NH3 is mixed with the air Air and burned in the first combustion furnace 10 by the first combustion burner 11 as described above, and the first exhaust gas Ga1 containing unburned ammonia NH3 is led to the second combustion furnace 20 through the first exhaust gas passage 14 as described above, 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 are controlled by the control means 30 to control the amount of the first exhaust gas Ga1 led to the second combustion furnace 20 through the first guide passage 15 and the amount of the first exhaust gas Ga1 led to the second combustion burner 21 provided in the second combustion furnace 20 through the second guide passage 16, as shown in FIG. 4, an ammonia concentration detector 18 that detects the concentration of unburned ammonia NH3 contained in the first exhaust gas Ga1 led to the first exhaust gas passage 14 can be provided, and the result detected by the ammonia concentration detector 18 can be output to the control means 30.

[0033] When the concentration of unburned ammonia NH3 contained in the first exhaust gas Ga1 detected by the ammonia concentration detector 18 is low, the amount of the first exhaust gas Ga1 guided to the second combustion burner 21 through the second guide path 16 is reduced by the control means 30, and the amount of the first exhaust gas Ga1 guided into the second combustion furnace 20 through the first guide path 15 is increased, so that the unburned ammonia NH3 contained in the first exhaust gas Ga1 is burned in the second combustion furnace 20. On the other hand, when the concentration of unburned ammonia NH3 contained in the first exhaust gas Ga1 detected by the ammonia concentration detector 18 is high, the amount of the first exhaust gas Ga1 supplied to the air supply pipe 23 in the second combustion burner 21 through the second guide path 16 is increased, and the first exhaust gas Ga1 is mixed with air Air through the air supply pipe 23 and mixed with the fuel G supplied through the fuel supply pipe 22, and burned in the second combustion furnace 20 by the second combustion burner 21.

[0034] In this manner, even if the concentration of unburned ammonia NH3 contained in the first exhaust gas Ga1 is low or even if the concentration of unburned ammonia NH3 contained in the first exhaust gas Ga1 is 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, as in the above case. [Explanation of symbols]

[0035] 10: First combustion furnace 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: 2nd guideway 16a: Flow control valve 17: Flame sensor 18: Ammonia concentration detector 20: Second combustion furnace 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: G: fuel Ga1: First exhaust gas Ga2: Second exhaust gas NH3: Ammonia

Claims

1. The present invention has a first combustion furnace equipped with a first combustion burner for burning ammonia, and a second combustion furnace to 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 fuel and air and burning the resulting mixture, a first guide passage for guiding the first exhaust gas containing unburned ammonia discharged from the first combustion furnace into the second combustion furnace, and a second guide passage for guiding the first exhaust gas containing unburned ammonia discharged from the first combustion furnace to the second combustion burner provided in the second combustion furnace, and an amount of the first exhaust gas containing unburned ammonia to be introduced into the first guide passage and the second guide passage is controlled by a control unit. and when an amount of unburned ammonia contained in the first exhaust gas is small, the control means increases the amount of the first exhaust gas that is guided into the second combustion furnace through the first guide path, thereby introducing the unburned ammonia into the second combustion furnace and burning it, while when an amount of unburned ammonia contained in the first exhaust gas is large, the control means increases the amount of the first exhaust gas that is guided into the second combustion burner through the second guide path, thereby increasing the amount of unburned ammonia that is burned together with the fuel.

2. 2. The ammonia combustion facility according to claim 1, wherein a diameter of the second guide passage is increased to reduce a flow velocity of the first exhaust gas guided to the second combustion burner through the second guide passage.

3. 3. The ammonia combustion facility according to claim 1 or 2, further comprising an ammonia concentration detection device that detects a concentration of unburned ammonia contained in a first exhaust gas discharged from the first combustion furnace, and the control means controls an amount of the first exhaust gas containing unburned ammonia to be 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. 3. The ammonia combustion facility according to claim 1 or 2, wherein, when combustion in the first combustion burner goes off and an 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 into the second combustion furnace through the first guide path, and guides the first exhaust gas to the second combustion burner through the second guide path, thereby burning the unburned ammonia together with the fuel.

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