Ammonia combustion facility

Abstract

To burn ammonia sufficiently to prevent unburnt ammonia from being left, and prevent NOx from occurring during combustion of ammonia, when mixing ammonia and air and burning them.SOLUTION: In an ammonia combustion facility where ammonia NH3 is mixed with air and burned, an air ratio for burning the ammonia NH3 is set to a range of 0.95 to 0.99.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an ammonia combustion facility for mixing ammonia with air and burning the ammonia. In particular, the present invention is characterized in that, when mixing ammonia with air and burning the ammonia, the ammonia is sufficiently burned to prevent unburned ammonia from remaining, and NOx is prevented from being generated during the combustion of ammonia. [Background technology]

[0002] 2. Description of the Related Art Combustion equipment that mixes fuel with combustion air and burns the mixture generally uses hydrocarbon fuel as the fuel.

[0003] However, when a hydrocarbon fuel is mixed with combustion air and burned in this manner, there is a problem in that a large amount of greenhouse gases such as carbon dioxide (CO2) is generated.

[0004] In recent years, there has been a demand for reducing greenhouse gases such as carbon dioxide (CO2), 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. However, ammonia has poor combustibility compared to hydrocarbon fuels, and it is difficult to completely combust ammonia. Unburned ammonia is likely to remain. Furthermore, when ammonia is burned vigorously to reduce the amount of unburned ammonia, the flame temperature becomes high, and the amount of NOx generated increases. This is a problem.

[0006] Patent Document 1 proposes that when ammonia, which is a low-combustibility fuel having poor combustibility as described above, is mixed with combustion air and burned, ammonia premixed with combustion air is selectively used to enhance the combustibility of ammonia.

[0007] However, even when ammonia, which is a low-combustibility fuel, is premixed with combustion air and used selectively in this way, there still remain problems that the ammonia is not sufficiently burned and unburned ammonia remains, and when the ammonia is burned strongly to reduce the amount of unburned ammonia, the flame temperature becomes high and the amount of NOx generated increases.

[0008] Furthermore, Patent Document 2 proposes that when a substance containing sulfur components, such as natural gas or pulverized coal, is burned as fuel, ammonia is injected from an ammonia injection port along the inner wall surface of a wall portion where no burner is installed, and the ammonia is burned in the vicinity of the inner wall surface of the wall portion, thereby preventing the wall portion from being eroded by hydrogen sulfide generated by the combustion of the sulfur components.

[0009] However, in the method disclosed in Patent Document 2, when ammonia itself is burned as described above, the effect of preventing unburned ammonia from remaining or an increase in the amount of NOx generated cannot be obtained. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] JP 2016-130619 A [Patent Document 2] JP 2020-139700 A DISCLOSURE OF THEINVENTION [Problem to be solved by the invention]

[0011] An object of the present invention is to solve the above-mentioned problems in ammonia combustion equipment in which ammonia is mixed with air and combusted.

[0012] That is, an object of the present invention is to prevent unburned ammonia from remaining by sufficiently burning ammonia when ammonia is mixed with air and burned in the ammonia combustion facility as described above, and to prevent NOx from being generated during the combustion of ammonia. [Means for solving the problem]

[0013] In the first ammonia combustion equipment according to the present invention, in order to solve the above-mentioned problems, in the ammonia combustion equipment in which ammonia is mixed with air and burned, the air ratio for burning ammonia is set in the range of 0.95 to 0.99.

[0014] Here, the present inventors conducted an experiment in which ammonia was mixed with air and burned, and investigated the relationship between the air ratio at which ammonia was burned, the amount of unburned ammonia that remains when ammonia is not sufficiently burned, and the amount of NOx generated when ammonia is burned. As a result, it was found that, as shown in FIG. 1, as the air ratio decreases, the amount of NOx generated decreases and becomes zero, and at the same time, there is a point at which unburned ammonia, which was zero, is generated, in other words, a point at which both the generation of NOx and the generation of unburned ammonia are close to zero.

[0015] Furthermore, the experimental results showed that the point at which both NOx emissions and unburned ammonia emissions are close to zero is when the air ratio for burning ammonia is in the range of 0.95 to 0.99. Here, in Figure 1, Experiment A shows the changes in the amount of NOx generated and the amount of unburned ammonia generated when the air ratio for burning ammonia was 0.95, which was the lowest, and Experiment B shows the changes in the amount of NOx generated and the amount of unburned ammonia generated when the air ratio for burning ammonia was 0.99, which was the highest.

[0016] In a second ammonia combustion facility according to the present invention, in an ammonia combustion facility in which ammonia is mixed with air and burned, a guide pipe for guiding the ammonia discharged from the ammonia discharge pipe into a furnace is provided on the outer periphery of the tip of the ammonia discharge pipe that discharges the ammonia, air is introduced into the guide pipe through an air inlet between the ammonia discharge pipe and the guide pipe, and the ammonia and air are jetted radially into the furnace from a plurality of radial jets provided radially on the outer periphery of the tip of the guide pipe to be combusted, with an air ratio for burning the ammonia set in the range of 0.95 to 0.99.

[0017] In the second ammonia combustion facility, ammonia is discharged from the ammonia discharge pipe into the guide pipe provided on the outer periphery of the tip of the ammonia discharge pipe, air is introduced into the guide pipe through the air inlet between the ammonia discharge pipe and the ammonia discharge pipe, and ammonia and air are jetted radially into the furnace from a plurality of radial jets provided radially on the outer periphery of the tip of the guide pipe to be combusted, so that the flame spreads radially near the inner wall surface of the furnace. Therefore, even when ammonia with low combustibility is jetted into the furnace and combusted, it is possible to prevent the flame from extending long into the furnace and directly hitting the workpiece in the furnace, which would result in poor finish of the workpiece, as in the conventional case.

[0018] Furthermore, in the second ammonia combustion facility, the air ratio for burning ammonia was set in the range of 0.95 to 0.99 as described above, so that the amount of unburned ammonia and the amount of NOx generated during combustion were also reduced.

[0019] Here, in the second ammonia combustion equipment, when the ammonia and air introduced into the guide pipe as described above are jetted radially into the furnace from a plurality of radial jets provided radially on the outer periphery of the tip of the guide pipe for combustion, the size of the air introduction part between the ammonia discharge pipe and the guide pipe can be adjusted by air introduction adjustment means to adjust the air ratio for burning the ammonia to be within the range of 0.95 to 0.99.

[0020] In addition, when adjusting the air ratio for burning ammonia to be in the range of 0.95 to 0.99 as described above, an air guide for guiding air into the furnace can be provided on the outer periphery of the guide tube, and the air guided into the furnace through the air guide can be mixed with the ammonia and air jetted radially into the furnace from a plurality of radial jets provided on the outer periphery of the tip of the guide tube as described above, and combusted. The amount of air thus guided into the furnace through the air guide can also be adjusted by a guide air adjustment means. Effect of the Invention

[0021] In the first and second ammonia combustion facilities of the present invention, the air ratio for burning ammonia is set to the range of 0.95 to 0.99, so that the ammonia is sufficiently burned during combustion as described above, and it is possible to prevent unburned ammonia from remaining, and also to prevent the generation of NOx during the combustion of ammonia.

[0022] Furthermore, in the second ammonia combustion equipment of the present invention, as described above, ammonia and air are combusted by being jetted radially into the furnace from a plurality of radial jets provided radially on the outer periphery of the tip of the guide tube. Therefore, even when ammonia, which has low flammability, is jetted into the furnace and combusted, the flame spreads radially near the wall of the furnace, preventing the flame from extending far into the interior of the furnace and directly hitting the material to be treated inside the furnace, as occurred in the conventional case, thereby preventing the flame from deteriorating the finish of the material to be treated. [Brief description of the drawings]

[0023] [Figure 1] FIG. 1 is a diagram showing the relationship between the air ratio at which ammonia is combusted, the amount of unburned ammonia remaining due to insufficient combustion, and the amount of NOx generated during ammonia combustion in the ammonia combustion equipment of the present invention. [Diagram 2]FIG. 1 is a schematic explanatory diagram showing a state in which ammonia is discharged from an ammonia discharge pipe into a guide pipe provided on the outer periphery of the tip of the ammonia discharge pipe, air is introduced into the guide pipe through an air inlet between the ammonia discharge pipe and the ammonia discharge pipe, and ammonia and air are jetted radially into a furnace from a plurality of radial jets provided radially on the outer periphery of the tip of the guide pipe to be combusted. [Diagram 3] FIG. 3 is an explanatory cross-sectional view along line A-A showing a state in which a guide section for guiding air into a furnace is provided on the outer periphery of a guide tube in the ammonia combustion equipment according to the embodiment shown in FIG. 2, and the amount of air guided into the furnace through the air guide section is adjusted by a guide air adjustment means. BEST MODE FOR CARRYING OUT THEINVENTION

[0024] 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.

[0025] In the ammonia combustion facility according to the embodiment of the present invention, as shown in FIG. 2, an ammonia discharge pipe 20 for discharging ammonia NH3 is inserted into the center of a support plate 12b supported by each support 12a attached to a mounting member 11 provided on an outer wall surface 10a of a furnace 10.

[0026] In addition, in the mounting member 11, a guide pipe 30 for guiding ammonia NH3 discharged from the ammonia discharge pipe 20 into the furnace 10 is attached to the center of the protruding portion 11a that is provided so as to protrude outward in a concave shape from the outer wall surface 10a of the furnace 10 so as to be located on the outer periphery of the tip of the ammonia discharge pipe 20, and a plurality of radiation nozzles 31 are provided in the radial direction on the outer periphery of the tip of the guide pipe 30 led into the furnace 10.

[0027] Here, in the ammonia combustion equipment of this embodiment, a screw portion 22 is provided on the outer periphery of the ammonia discharge pipe 20, and an air introduction adjustment means 40 is provided which rotates in mesh with the screw portion 22 on the outer periphery of the ammonia discharge pipe 20 and moves in the axial direction of the ammonia discharge pipe 20, and the size of the air introduction portion S1 between the ammonia discharge pipe 20 and the guide pipe 30 is adjusted by the air introduction adjustment means 40.

[0028] In addition, the inner diameter of the discharge port 21 at the tip of the ammonia discharge pipe 20 is tapered toward the direction in which the ammonia NH3 is discharged, so that the ammonia NH3 guided into the ammonia discharge pipe 20 is forcefully discharged from the contracted discharge port 21 into the guide pipe 30.

[0029] In addition, by combining this with a diffuser structure in which the inner diameter of the flow passage 33 in the guide pipe 30 is gradually contracted in the flow direction and then expanded again, an ejector effect is generated, enabling the air to be ejected with even greater force.

[0030] When ammonia NH3 is forcefully ejected from the outlet 21 of the ammonia ejection pipe 20 into the guide pipe 30 in this manner, air Air is sucked between the ammonia ejection pipe 20 and the guide pipe 30 through the air introduction section S1, and the sucked air Air is mixed with the ammonia NH3 ejected into the guide pipe 30 and is guided to the tip of the guide pipe 30, and is ejected in the radial direction near the inner wall surface 10b of the furnace 10 from the multiple radial ejection ports 31 provided on the outer periphery of the tip of the guide pipe 30.

[0031] In addition, in the ammonia combustion equipment of this embodiment, an air guide section 32 that guides air (Air) into the furnace 10 is provided on the outer periphery of the guide tube 30, and as a guide air adjustment means for adjusting the amount of air (Air) guided to the air guide section 32, a plurality of introduction holes 51 that guide air (Air) to the air guide section 32 are provided in the protrusion 11a of the mounting member 11, and air adjustment holes 53 are provided in a ring-shaped rotating plate 52 that rotates in contact with the surface of the protrusion 11a, so as to correspond to each introduction hole 51 provided in the protrusion 11a.

[0032] To adjust the amount of air (Air) guided into the furnace 10 through the air guide section 32, as shown in FIG. 3, the rotating plate 52 is rotated to change the area of ​​the portion where the inlet hole 51 in the protruding portion 11a communicates with the air adjustment hole 53 in the rotating plate 52, thereby adjusting the amount of air guided to the air guide section 32 through the inlet hole 51 and the air adjustment hole 53. In this way, an appropriate amount of air (Air) is supplied into the furnace 10 through the air guide section 32.

[0033] Here, in the ammonia combustion equipment of this embodiment, as described above, ammonia NH3 is ejected from the outlet 21 of the ammonia ejection pipe 20 into the guide pipe 30, and air Air is sucked between the ammonia ejection pipe 20 and the guide pipe 30 through the air introduction part S1, and while the air Air is mixed together with the ammonia NH3 in the guide pipe 30, the ammonia NH3 and the air Air are ejected in the radial direction into the furnace 10 along the inner wall surface 10b of the furnace 10 from a plurality of radial ejection ports 31 provided on the outer periphery of the tip of the guide pipe 30, and an appropriate amount of air Air is supplied into the furnace 10 through the air guide part 32 on the outer periphery side of the guide pipe 30, and the ammonia NH3 is burned with the air ratio in the range of 0.95 to 0.99 with the air Air added.

[0034] In this way, as shown in FIG. 1, the amount of unburned ammonia (NH3) generated during combustion and the amount of NOx generated can be reduced. In particular, when the air ratio for burning ammonia (NH3) is set to about 0.97, the amount of unburned ammonia generated and the amount of NOx generated can be significantly reduced.

[0035] In addition, in the ammonia combustion equipment of this embodiment, as described above, ammonia NH3 and air Air are ejected radially into the furnace 10 from a plurality of radial ejection ports 31 provided on the outer periphery of the tip of the guide tube 30 along the inner wall surface 10b of the furnace 10, and an appropriate amount of air Air is supplied into the furnace 10 through the air guide section 32 on the outer periphery of the guide tube 30 to combust ammonia NH3. This causes the flame to spread radially near the inner wall surface 10b of the furnace 10, preventing the flame from extending too far into the furnace 10. When a workpiece (not shown) is heat-treated in the furnace 10, the flame is prevented from directly hitting the workpiece, which can prevent the finish of the workpiece from being deteriorated.

[0036] In the ammonia combustion equipment of this embodiment, as described above, ammonia NH3 and air Air are jetted radially into the furnace 10 along the inner wall surface 10b of the furnace 10 from the multiple radial jets 31 provided on the outer periphery of the tip of the guide tube 30, but the ammonia combustion equipment of the present invention is not limited to the above.

[0037] For example, although not shown, a mixture of ammonia NH3 and air may be ejected from the tip of an ejection pipe (not shown) into the furnace. In this case, too, by burning ammonia NH3 with an air ratio in the range of 0.95 to 0.99 as described above, the amount of unburned ammonia NH3 and the amount of NOx generated during combustion can be reduced. [Explanation of symbols]

[0038] 10: Furnace 10a: Exterior wall surface 10b: Inner wall surface 11: Mounting material 11a:Protrusion 12a: Post 12b: Support plate 20: Ammonia discharge pipe 21:Discharge port 22: Screw part 30: Guide tube 31: Radiation spout 32: Air guide section 33: Flow path 40: Air introduction adjustment means 51: Introduction hole 52: Rotating plate 53: Air adjustment hole Air: NH3: Ammonia S1: Air intake section

Claims

1. 1. An ammonia combustion facility for burning ammonia mixed with air, characterized in that the air ratio for burning ammonia is set in the range of 0.95 to 0.

99.

2. In an ammonia combustion facility for burning ammonia mixed with air, a guide pipe for guiding the ammonia discharged from the ammonia discharge pipe into a furnace is provided on the outer periphery of the tip of the ammonia discharge pipe for discharging the ammonia, air is introduced into the guide pipe through an air inlet between the ammonia discharge pipe and the guide pipe, and the ammonia and air are jetted radially into the furnace from a plurality of radial jets provided radially on the outer periphery of the tip of the guide pipe to be combusted, the ammonia combustion facility being characterized in that an air ratio for burning the ammonia is set in the range of 0.95 to 0.

99.

3. 3. The ammonia combustion facility according to claim 2, further comprising an air introduction adjusting means for adjusting the size of the air introduction portion between the ammonia discharge pipe and the guide pipe.

4. 4. The ammonia combustion facility according to claim 2 or 3, wherein an air guide section for guiding air into the furnace is provided on the outer periphery of the guide tube, and the air guided into the furnace through the air guide section is mixed with the ammonia and air jetted radially into the furnace from a plurality of radial jets provided on the outer periphery of the tip of the guide tube along the inner wall surface of the furnace, and combusted, with an air ratio for burning the ammonia in the range of 0.95 to 0.

99.

5. 5. The ammonia combustion facility according to claim 4, further comprising an air guide adjusting means for adjusting the amount of air guided into the furnace through said air guide portion.

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