Radiant burner

Abstract

A radiant burner 100 comprises a burner tile 1 and a nozzle 2 protruding from the burner tile 1 toward a combustion space S. The nozzle 2 comprises: a first fuel injection hole 25 through which a first fuel containing ammonia is injected into the combustion space S; a first fuel flow path 23 in fluid communication with the first fuel injection hole 25; a preheating space P separated from the first fuel injection hole 25 and the first fuel flow path 23 by a wall and adjacent to the first fuel flow path 23 with the wall therebetween; and a second fuel injection hole 26 that opens into the preheating space P and injects a second fuel into the preheating space P.

Description

radiant burner

[0001] This application claims the benefit of priority from Japanese Patent Application No. 2023-170183, filed on September 29, 2023, the contents of which are incorporated herein by reference.

[0002] A radiant burner heats the surface of a burner tile by burning fuel and heats an object by radiant heat from the heated surface. For example, Patent Document 1 discloses such a radiant burner. In this radiant burner, a fuel-air mixture outlet is positioned away from the bottom of a cup. An impingement plate is provided facing the outlet. The impingement plate changes the direction of the mixture from the outlet. The impingement plate guides the mixture radially outward toward the surface of the cup. With this configuration, the mixture impacts the surface of the cup and decelerates. Therefore, it takes a longer time for the mixture to impact the surface of the cup again. During this time, the mixture is sufficiently heated and combusted. With this configuration, problems such as insufficient combustion of the fuel are solved when fuels with slow combustion speeds, such as natural gas or liquefied petroleum gas, are used.

[0003] Japanese Utility Model Laid-Open Publication No. 51-58438

[0004] Ammonia is CO ２ However, the burning rate of ammonia is much slower than that of natural gas. Therefore, when using ammonia in a radiant burner, the flammability of the fuel can be an issue.

[0005] An object of the present disclosure is to provide a radiant burner that can improve the combustibility of fuel when ammonia is used as fuel.

[0006] A radiant burner according to one aspect of the present disclosure comprises a burner tile; and a nozzle protruding from the burner tile toward a combustion space, the nozzle including: a first fuel injection hole for injecting a first fuel containing ammonia into the combustion space; a first fuel flow path fluidly connected to the first injection hole; a preheating space separated from the first fuel injection hole and the first fuel flow path by a wall and adjacent to the first fuel flow path across the wall; and a second fuel injection hole opening into the preheating space for injecting a second fuel into the preheating space.

[0007] A first mixed gas of a first fuel and an oxidizer may be supplied to the first fuel flow passage, and a second mixed gas of a second fuel and an oxidizer may be supplied to the second fuel injection hole.

[0008] The nozzle may include a first oxidizer injection hole facing the area opposite the first fuel injection hole and injecting oxidizer, and a second oxidizer injection hole facing the area opposite the second fuel injection hole and injecting oxidizer.

[0009] The nozzle may include a catalyst disposed in the first fuel flow passage at a position adjacent to the preheating space across the wall.

[0010] The nozzle may extend along a central axis, the preheating space may be disposed on the central axis, and the first fuel flow path may be disposed outside the preheating space around the central axis so as to surround the preheating space.

[0011] The preheat space may open to the combustion space on the central axis, and the nozzle may include a through-hole extending from the preheat space to the combustion space in a direction transverse to the central axis and passing through the first fuel flow passage.

[0012] The nozzle may extend along a central axis, the preheating space may include a plurality of preheating sections, the first fuel flow path may include a plurality of first branch fuel flow paths, and the plurality of preheating sections and the plurality of first branch fuel flow paths may be arranged alternately with each other around the central axis.

[0013] According to the present disclosure, when ammonia is used as fuel in a radiant burner, the combustibility of the fuel can be improved.

[0014] FIG. 1 is a schematic cross-sectional view showing a radiant burner according to a first embodiment. FIG. 2 is a schematic front view showing the radiant burner of FIG. 1. FIG. 3 is a schematic cross-sectional view showing a radiant burner according to a second embodiment. FIG. 4 is a schematic cross-sectional view showing a radiant burner according to a third embodiment. FIG. 5 is a schematic cross-sectional view showing a radiant burner according to a fourth embodiment. FIG. 6 is a schematic cross-sectional view showing a radiant burner according to a fifth embodiment. FIG. 7 is a schematic front view showing the radiant burner of FIG. 6. FIG. 8 is a schematic enlarged cross-sectional view of a nozzle in FIG. 6. FIG. 9 is a schematic enlarged front view of a nozzle in FIG. 7. FIG. 10 is a schematic enlarged cross-sectional view showing a radiant burner according to a sixth embodiment. FIG. 11 is a schematic enlarged front view showing the radiant burner of FIG. 10. FIG. 12 is a schematic enlarged cross-sectional view showing a radiant burner according to a seventh embodiment. FIG. 13 is a schematic enlarged front view showing the radiant burner of FIG. 12.

[0015] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Specific dimensions, materials, numerical values, etc. shown in the embodiments are merely examples for ease of understanding and do not limit the present disclosure unless otherwise specified. In this specification and drawings, elements having substantially the same functions and configurations are designated by the same reference numerals to avoid redundant explanation, and elements not directly related to the present disclosure are not shown.

[0016] Fig. 1 is a schematic cross-sectional view showing a radiant burner 100 according to a first embodiment. Fig. 2 is a schematic front view showing the radiant burner 100 of Fig. 1.

[0017] 1 , the radiant burner 100 heats the surface 11 of the burner tile 1 by burning a mixed gas containing ammonia, and uses radiant heat from the heated surface 11 to heat an object (not shown) located at a distance from the radiant burner 100. For example, the radiant burner 100 includes a burner tile 1 and a nozzle 2. The radiant burner 100 may further include other components.

[0018] The burner tile 1 is formed of a refractory material, such as a molded product containing ceramic. Referring to Fig. 2, in this embodiment, the burner tile 1 has a generally rectangular parallelepiped shape. The burner tile 1 is not limited to this and may have other shapes. Referring to Fig. 1, the burner tile 1 includes a front surface 12 arranged to face the object, and a back surface 13 opposite the front surface 12.

[0019] In this embodiment, the burner tile 1 includes a recess 14 on the front surface 12. The recess 14 is formed from the front surface 12 toward the back surface 13. The recess 14 is defined by the surface 11. The recess 14 is used as a combustion space S. In this disclosure, the "combustion space" means a space in which a mixed gas is combusted. In this embodiment, the recess 14 has a hemispherical shape. In other embodiments, the recess 14 may have other shapes, such as a cylindrical shape or a polygonal prism shape. In other embodiments, the burner tile 1 may not include the recess 14.

[0020] In this disclosure, the burner tile 1 may also be referred to as a "radiant cup." Also, in this disclosure, the radiant burner 100 may also be referred to as a "radiant cup burner."

[0021] The nozzle 2 extends along a central axis X. In the present disclosure, the "central axial direction," "radial direction," and "circumferential direction" of the nozzle 2 may be simply referred to as the "central axial direction," "radial direction," and "circumferential direction." The nozzle 2 protrudes from the burner tile 1 toward the combustion space S. Referring to FIG. 2 , in this embodiment, the nozzle 2 is located at the center of the recess 14 when viewed in the central axial direction.

[0022] 1 , in this embodiment, the nozzle 2 includes a pipe (first pipe) 21 and a pipe (second pipe) 22. In this embodiment, the pipes 21 and 22 are arranged concentrically with each other. In this embodiment, the central axis X of the nozzle 2 coincides with the central axes of the pipes 21 and 22.

[0023] The tube 21 has a generally cylindrical or tubular shape. The tube 21 is attached to the burner tile 1. The tube 21 penetrates the wall of the burner tile 1 from the rear surface 13 and protrudes into the recess 14. With reference to Figure 2, the tube 21 is located at the center of the hemispherical recess 14 when viewed in the direction of the central axis.

[0024] 1, the tube 22 has a generally cylindrical or tubular shape. The outer diameter of the tube 22 is smaller than the inner diameter of the tube 21. The tube 22 is inserted into the tube 21. The tube 22 protrudes from the back surface 13 into the recess 14.

[0025] The radial gap between the tube 21 and the tube 22 functions as a flow path (first fuel flow path) 23. A first fuel containing ammonia is supplied to the flow path 23. In this embodiment, a first mixed gas of the first fuel and an oxidizer (e.g., air) is supplied to the flow path 23 (premixing method).

[0026] The inside of the tube 22 functions as a flow path (second fuel flow path) 24. In this embodiment, the flow paths 23 and 24 are independent of each other. A second fuel is supplied to the flow path 24. For example, the second fuel may be the same as the first fuel. For example, the second fuel may contain ammonia. Also, for example, in this embodiment, since the flow paths 23 and 24 are independent of each other, the second fuel may be different from the first fuel. For example, the second fuel may not contain ammonia. For example, the second fuel may contain a fuel that has a faster burning speed than ammonia. In this embodiment, a second mixed gas of the second fuel and an oxidizer (e.g., air) is supplied to the flow path 24 (premixing method). The second mixed gas may be the same as the first mixed gas or may be different from the first mixed gas.

[0027] The nozzle 2 includes an injection hole (first fuel injection hole) 25 and an injection hole (second fuel injection hole) 26 .

[0028] Specifically, in this embodiment, the end of the tube 21 tapers toward the combustion space S. Inside the end of the tube 21, the tube 22 also tapers toward the combustion space S and extends beyond the end of the tube 21 into the combustion space S. The tube 22 includes a constriction 27 in the tapered portion. Furthermore, the end of the tube 22 bends radially outward toward the back surface 13. The end of the tube 22 surrounds the outer surface of the tube 21. A radial gap between the end of the tube 22 and the outer surface of the tube 21 functions as an injection hole 25. In this embodiment, the injection hole 25 has an annular shape. The injection hole 25 opens radially outward. Furthermore, the injection hole 25 opens in the axial direction so as to face the surface 11 of the burner tile 1.

[0029] The injection holes 25 are in fluid communication with the flow paths 23 to which the first mixed gas is supplied. Therefore, the injection holes 25 inject the first mixed gas into the combustion space S. Specifically, the injection holes 25 inject the first mixed gas toward the surface 11 of the burner tile 1. Therefore, a flow of the first mixed gas along the surface 11 is formed.

[0030] In this embodiment, the pipe 22 includes a partition 28. The partition 28 is disposed inside the pipe 22. The partition 28 divides the flow path 24 in the axial direction. The injection holes 26 penetrate the partition 28 in the axial direction. Two injection holes 26 are shown in FIG. 1 . However, the number of injection holes 26 is not limited to two, and one injection hole 26, or three or more injection holes 26 may be formed.

[0031] The space inside the tube 22 between the orifice 27 and the partition 28 functions as a preheating space P. The preheating space P is separated from the injection holes 25 and the flow path 23 by the wall of the tube 22. The preheating space P is adjacent to the flow path 23, with the wall of the tube 22 in between. In this embodiment, the preheating space P is located on the central axis X. In this embodiment, the preheating space P opens into the combustion space S at the orifice 27 on the central axis X. In this embodiment, the flow path 23 is arranged outside the preheating space P around the central axis X so as to surround the preheating space P.

[0032] The injection holes 26 open into the preheating space P. The injection holes 26 inject the second mixed gas into the preheating space P. In this embodiment, the injection holes 26 inject the second mixed gas in the axial direction. In other embodiments, the injection holes 26 may be inclined radially outward so as to inject the second mixed gas toward the wall of the tube 22.

[0033] The nozzle 2 contains a catalyst C in the flow path 23. Specifically, the catalyst C is disposed in the flow path 23 at a position adjacent to the preheating space P across the wall of the tube 22. However, the catalyst C is not essential.

[0034] For example, the catalyst C includes a transition element (which may also be referred to as a transition metal). For example, the catalyst C may include a noble metal such as Ru. Alternatively, for example, the catalyst C may include a non-noble metal such as Fe, Co, Ni, or Cu among the transition elements. The non-noble metal may exhibit high activity when combined with a specific support. Examples of the support include Al. ２ O ３ or SiO ２ Oxides such as CeO may also be used as needed. ２ A carrier capable of suppressing sintering such as may be used.

[0035] Ammonia in the first mixed gas flowing through the flow path 23 reacts on the catalyst C, causing the following reactions (1), (2), or a combination thereof: (1) NH ３ →1.5H ２ +0.5N ２ ΔH=45.4 (kJ / mol) (2) 2NH ３ +1.5O ２ →N ２ +3H ２ O ΔH=-382.6 (kJ / mol)

[0036] For example, in this embodiment, catalyst C can cause both reactions (1) and (2). The amounts of ammonia and oxidizer in the first mixed gas may be adjusted so that the ratios of reactions (1) and (2) are within intended ranges.

[0037] Next, the operation of the radiant burner 100 will be described.

[0038] A first mixed gas containing ammonia is supplied to the flow passage 23. The first mixed gas is injected into the combustion space S from the injection holes 25 toward the surface 11.

[0039] A second mixed gas is supplied to the flow path 24. The second mixed gas is injected into the preheating space P through the injection holes 26. The nozzle 2 is configured so that the second mixed gas is ignited in the preheating space P. Accordingly, a flame PF is formed in the preheating space P (which may also be referred to as a "preheating flame" in the present disclosure). Note that a portion of the preheating flame PF may protrude from the preheating space P into the combustion space S. For example, in this embodiment, factors such as the flow rate and composition of the second mixed gas may be adjusted so that the second mixed gas is ignited in the preheating space P. Furthermore, for example, dimensions such as the size of the preheating space P and the orifice 27 may be designed so that the second mixed gas having an intended flow rate and composition is ignited in the preheating space P.

[0040] The preheating space P is at least partially separated from the combustion space S by the wall of the tube 22. Therefore, the second mixture gas is less likely to mix with the combustion gas in the combustion space S. As a result, the combustibility of the second mixture gas is improved. The combustion gas in the preheating space P is discharged into the combustion space S through the orifice 27.

[0041] The wall of the tube 22 surrounding the preheating space P is heated by the preheating flame PF. As described above, the flow path 23 is adjacent to the preheating space P across the wall of the tube 22. Therefore, the first mixed gas flowing through the flow path 23 is heated by the wall of the tube 22. Particularly in this embodiment, the flow path 23 is disposed outside the preheating space P so as to surround the preheating space P. Therefore, the heat transfer area between the preheating space P and the flow path 23 is increased, and the first mixed gas is more easily heated. Because the first mixed gas is heated, the combustibility of ammonia in the first mixed gas is improved. As a result, the combustibility of the first mixed gas is improved.

[0042] The first mixture gas injected from the injection hole 25 is heated and ignited by the surface 11. Therefore, a flame F is formed in the combustion space S along the surface 11 (which may also be referred to as a "main flame" in this disclosure). As described above, the combustibility of the first mixture gas is improved, making the first mixture gas more likely to ignite. For example, in this embodiment, factors such as the flow rate and composition of the first mixture gas may be adjusted so that the first mixture gas ignites in a region along the surface 11. The improved combustibility of the first mixture gas increases the temperature of the main flame F. As a result, the surface 11 is heated to a higher temperature. Furthermore, the improved combustibility of the first mixture gas reduces the amount of unburned ammonia. As a result, the phenomenon of unburned ammonia cooling the surface 11 is suppressed, and the surface 11 is heated to a higher temperature. Therefore, the performance of the radiant burner 100 is improved.

[0043] If the first mixture gas is not heated, the combustion speed of ammonia is slow, and therefore the main flame F is likely to be formed at a more downstream position. In this case, there is a possibility that the main flame F will be formed outside the recess 14. However, in this embodiment, the first mixture gas is heated, and the combustibility of the first mixture gas is improved, so that the flow rate of the first mixture gas into the combustion space S can be reduced. As a result, the main flame F is likely to be formed at the intended position.

[0044] In addition, a catalyst C is disposed in the flow path 23. A portion of the ammonia flowing through the flow path 23 is decomposed into hydrogen at the catalyst C. The combustion rate of hydrogen is faster than that of ammonia. Therefore, the combustibility of the first mixed gas is improved. In addition, another portion of the ammonia flowing through the flow path 23 causes catalytic combustion at the catalyst C. The first mixed gas is heated by the catalytic combustion. Therefore, the ammonia in the first mixed gas is heated by the catalytic combustion, further improving the combustibility of the first mixed gas.

[0045] As described above, the radiant burner 100 according to this embodiment includes a burner tile 1 and a nozzle 2 protruding from the burner tile 1 toward the combustion space S. The nozzle 2 includes an injection hole 25 for injecting a first fuel containing ammonia into the combustion space S, a flow path 23 fluidly communicating with the injection hole 25, a preheating space P separated from the injection hole 25 and the flow path 23 by a wall of a tube 22 and adjacent to the flow path 23 across the wall of the tube 22, and an injection hole 26 opening into the preheating space P and for injecting a second fuel into the preheating space P. With this configuration, a preheating flame PF is formed in the preheating space P. The wall of the tube 22 surrounding the preheating space P is heated by the preheating flame PF. The flow path 23 is adjacent to the preheating space P across the wall of the tube 22. Therefore, the first mixed gas flowing through the flow path 23 is heated by the wall of the tube 22. As a result, the combustibility of the ammonia in the first mixed gas is improved, and the combustibility of the first mixed gas is improved.

[0046] Furthermore, with this configuration, the preheating space P is at least partially separated from the combustion space S by the wall of the tube 22. Therefore, the second mixture gas is less likely to mix with the combustion gas in the combustion space S. As a result, the combustibility of the second mixture gas is improved.

[0047] Furthermore, with this configuration, the unburned gas temperature of the first mixed gas increases, and therefore the temperature of the main flame F increases. As a result, the surface 11 is heated to a higher temperature. Furthermore, the combustibility of the first mixed gas is improved, and the amount of unburned ammonia is reduced. As a result, the phenomenon of unburned ammonia cooling the surface 11 is suppressed, and the surface 11 is heated to a higher temperature. Therefore, the performance of the radiant burner 100 is improved.

[0048] Furthermore, with this configuration, the required heat can be supplemented by the heat from preheating in addition to the combustion heat of the first mixture gas, thereby reducing the flow rate of the first mixture gas into the combustion space S. As a result, the main flame F is more likely to be formed at the intended position.

[0049] In the radiant burner 100, a mixed gas of the first fuel and oxidizer is supplied to the flow passage 23, and a mixed gas of the second fuel and oxidizer is supplied to the injection holes 26 (premixing method). This configuration prevents the generation of unburned fuel due to insufficient mixing. It also makes it easier to control the combustion temperature and NOx emissions.

[0050] Furthermore, in the radiant burner 100, the nozzle 2 includes a catalyst C that is disposed in the flow path 23 at a position adjacent to the preheating space P across the wall of the tube 22. With this configuration, a portion of the ammonia flowing through the flow path 23 is decomposed into hydrogen by the catalyst C. Another portion of the ammonia flowing through the flow path 23 causes catalytic combustion by the catalyst C. Therefore, the combustibility of the first mixed gas is further improved.

[0051] In the radiant burner 100, the nozzle 2 extends along the central axis X, the preheating space P is disposed on the central axis X, and the flow path 23 is disposed outside the preheating space P around the central axis X so as to surround the preheating space P. With this configuration, the heat transfer area between the preheating space P and the flow path 23 is increased, making it easier for the first mixed gas to be heated.

[0052] Next, a radiant burner according to another embodiment will be described.

[0053] 3 is a schematic cross-sectional view showing a radiant burner 100A according to the second embodiment. The radiant burner 100A differs from the radiant burner 100 according to the first embodiment in the shape of the burner tile 1. The other configurations of the radiant burner 100A may be the same as those of the radiant burner 100.

[0054] In this embodiment, the burner tile 1 does not include a recess. The nozzles 2 protrude from a front surface 12 of the burner tile 1. In this embodiment, the space facing the front surface 12 functions as the combustion space S. With this configuration, the main flame F is formed in the combustion space S along the front surface 12.

[0055] The radiant burner 100A as described above can achieve the same effects as the radiant burner 100 according to the first embodiment.

[0056] 4 is a schematic cross-sectional view showing a radiant burner 100B according to the third embodiment. The radiant burner 100B differs from the radiant burner 100 according to the first embodiment in that the nozzle 2 includes a through-hole 29. Furthermore, in the radiant burner 100B, the nozzle 2 does not include the catalyst C. In other respects, the radiant burner 100B may be the same as the radiant burner 100.

[0057] Specifically, the through hole (through pipe) 29 extends from the preheating space P to the combustion space S in a direction intersecting the central axis X, which in this embodiment is a direction perpendicular to the central axis X. The through hole 29 penetrates the flow path 23. Note that the space within the through hole 29 and the space within the flow path 23 are not in fluid communication with each other. In the example of FIG. 1 , the nozzle 2 includes a single through hole 29. However, the nozzle 2 may include multiple through holes 29.

[0058] In the radiant burner 100B, the combustion gas in the preheating space P is discharged into the combustion space S through the through holes 29. The combustion gas in the combustion space S is also drawn into the preheating space P through the orifice (opening) 27. Since the combustion gas has a high temperature, the combustibility of the second mixed gas in the preheating space P is improved.

[0059] The radiant burner 100B as described above can achieve the same effects as the radiant burner 100 according to the first embodiment.

[0060] In particular, in the radiant burner 100B, the preheating space P opens into the combustion space S on the central axis X, and the nozzle 2 extends from the preheating space P to the combustion space S in a direction intersecting the central axis X and includes a through-hole 29 penetrating the flow path 23. With this configuration, high-temperature combustion gas in the combustion space S is drawn into the preheating space P through the orifice 27. Therefore, the combustibility of the second mixture gas in the preheating space P is improved.

[0061] 5 is a schematic cross-sectional view showing a radiant burner 100C according to the fourth embodiment. The radiant burner 100C differs from the radiant burner 100 according to the first embodiment in that the radiant burner 100C uses a diffusion method. In other respects, the radiant burner 100C may be the same as the radiant burner 100.

[0062] Specifically, in this embodiment, the nozzle 2 includes a pipe (third pipe) 31 and a pipe (fourth pipe) 32 .

[0063] The tube 31 has a generally cylindrical or tubular shape. In this embodiment, the tube 31 is arranged concentrically with the tubes 21 and 22. The inner diameter of the tube 31 is larger than the outer diameter of the tube 21. The tube 21 is inserted into the tube 31. The tube 31 is attached to the burner tile 1. A radial gap between the tube 31 and the tube 21 functions as a flow path (first oxidant flow path) 33.

[0064] The end of the tube 31 is generally flush with the bottom of the recess 14. The end of the tube 31 functions as an injection hole (first oxidizer injection hole) 35. The injection hole 35 is in fluid communication with the flow path 33. The injection hole 35 faces the area (the space around the bottom of the recess 14) that the injection hole 25 faces.

[0065] The tube 32 has a generally cylindrical or tubular shape. In this embodiment, the tube 32 is arranged concentrically with the tubes 21, 22, and 31. The outer diameter of the tube 32 is smaller than the inner diameter of the tube 22. The tube 32 is inserted into the tube 22. The tube 32 is attached to the partition 28. The tube 32 axially penetrates the partition 28. The inside of the tube 32 functions as a flow path (second oxidant flow path) 34.

[0066] The end of the tube 32 is flush with the surface of the partition 28 that faces the preheating space P. The end of the tube 32 functions as an injection hole (second oxidizer injection hole) 36. The injection hole 36 is in fluid communication with the flow path 34. The injection hole 36 faces the region (preheating space P) that the injection hole 26 faces.

[0067] In this embodiment, only the first fuel is supplied to the flow path 23. Therefore, the injection hole 25 injects only the first fuel into the combustion space S. Only the oxidizer (e.g., air) is supplied to the flow path 33. Therefore, the injection hole 35 injects only the oxidizer into the combustion space S. Both the injection hole 25 and the injection hole 35 face the space around the bottom of the recess 14. Therefore, the first fuel and the oxidizer are mixed in this space and then combusted (diffusion method).

[0068] In this embodiment, only the second fuel is supplied to the flow path 24. Therefore, the injection holes 26 inject only the second fuel into the preheating space P. Only the oxidizer (e.g., air) is supplied to the flow path 34. Therefore, the injection holes 36 inject only the oxidizer into the preheating space P. Both the injection holes 26 and 36 face the preheating space P. Therefore, the second fuel and the oxidizer are mixed in the preheating space P and then combusted (diffusion method).

[0069] The radiant burner 100C as described above can achieve the same effects as the radiant burner 100 according to the first embodiment.

[0070] In particular, in the radiant burner 100C, the nozzle 2 includes an injection hole 35 for injecting an oxidizer facing the area where the injection holes 25 for injecting the first fuel face, and an injection hole 36 for injecting an oxidizer facing the area where the injection holes 26 for injecting the second fuel face (diffusion type). This configuration prevents the risk of the preheated first fuel igniting inside the nozzle and damaging the nozzle. It also makes it easier to ensure flame stability against load fluctuations.

[0071] In this embodiment, the nozzle 2 includes both the pipe 31 and the pipe 32. In another embodiment, the nozzle 2 may include only one of the pipe 31 and the pipe 32. In this case, only one of the first fuel and the second fuel is supplied in a diffusion manner.

[0072] Fig. 6 is a schematic cross-sectional view showing a radiant burner 100D according to a fifth embodiment. Fig. 7 is a schematic front view showing the radiant burner 100D of Fig. 6. Referring to Fig. 6, the radiant burner 100D differs from the radiant burner 100 according to the first embodiment in the structure of the nozzle 2. In other respects, the radiant burner 100D may be the same as the radiant burner 100.

[0073] Specifically, in this embodiment, the nozzle 2 includes a pipe (main pipe) 41 .

[0074] The tube 41 has a generally cylindrical or tubular shape. The tube 41 is attached to the burner tile 1. The tube 41 penetrates the wall of the burner tile 1 from the rear surface 13 and protrudes into the recess 14. Referring to Fig. 7, the tube 41 is located at the center of the hemispherical recess 14 when viewed in the direction of the central axis.

[0075] 6 , the inside of the pipe 41 functions as a flow path (main flow path) 42. A first fuel containing ammonia is supplied to the flow path 42. In this embodiment, a first mixed gas of the first fuel and an oxidizer (e.g., air) is supplied to the flow path 42 (premixing method).

[0076] Fig. 8 is a schematic enlarged cross-sectional view of the nozzle 2 in Fig. 6. The nozzle 2 includes an injection hole (first fuel injection hole) 43, an injection hole (second fuel injection hole) 44, a flow path (first fuel flow path) 45, and a preheating space P.

[0077] Specifically, in this embodiment, the end of the tube 41 includes a central projection 46 and a plurality of ribs 47 .

[0078] The central protrusion 46 has a generally cylindrical or tubular shape. The diameter of the central protrusion 46 is smaller than the maximum diameter of the tube 41. The central protrusion 46 is disposed on the central axis X. The flow passage 42 extends to the inside of the central protrusion 46. The axial end of the central protrusion 46 (the axial end of the tube 41) is closed.

[0079] 9 is a schematic enlarged front view of the nozzle 2 in FIG. 7. A plurality of ribs 47 are arranged radially outward from the central projection 46. The plurality of ribs 47 are arranged spaced apart from one another along the circumferential direction. The ribs 47 are connected to the central projection 46. The ribs 47 extend radially outward from the central projection 46 to the outermost diameter portion of the tube 41.

[0080] Referring to FIG. 8, the flow passage 45 includes a plurality of branch flow passages (first branch fuel flow passages) 45a.

[0081] Specifically, the branch flow passages 45a are formed inside the ribs 47. The branch flow passages 45a extend in the radial direction. The branch flow passages 45a penetrate the ribs 47 from the flow passages 42 to the combustion space S. The branch flow passages 45a are fluidly connected to the flow passages 42 to which the first mixed gas is supplied. Therefore, the first mixed gas is supplied to the branch flow passages 45a. Referring to FIG. 9 , the multiple branch flow passages 45a are arranged spaced apart from one another in the circumferential direction.

[0082] Referring to FIG. 8, the injection hole 43 includes a plurality of branch injection holes (first branch fuel injection holes) 43a.

[0083] Specifically, the radially outer end of the branch flow passage 45a functions as the branch injection hole 43a. The branch injection hole 43a injects the first mixed gas into the combustion space S. In the present embodiment, the branch injection hole 43a injects the first mixed gas radially outward.

[0084] The preheating space P includes a plurality of preheating sections PC.

[0085] Referring to FIG. 9 , specifically, a circumferential gap between adjacent ribs 47 functions as a single preheating section PC. Therefore, the multiple ribs 47 and the multiple preheating sections PC are arranged alternately along the circumferential direction. Furthermore, because the branch flow passages 45a are formed inside the ribs 47, the multiple branch flow passages 45a and the multiple preheating sections PC are also arranged alternately along the circumferential direction. The preheating section PC is separated from the branch injection holes 43a and the branch flow passages 45a by the wall of the rib 7. The preheating section PC is adjacent to the branch flow passage 45a, with the wall of the rib 7 sandwiched between them. The multiple preheating sections PC are arranged radially outward of the central protrusion 46. The multiple preheating sections PC are arranged spaced apart from one another along the circumferential direction.

[0086] Referring to FIG. 8, the injection hole 44 includes a plurality of branch injection holes (second branch fuel injection holes) 44a.

[0087] Specifically, of the surfaces defining the preheating section PC, the surface facing the axial direction includes the branch injection hole 44a. The branch injection hole 44a extends in the axial direction. The branch injection hole 44a penetrates the wall of the pipe 41 from the flow path 42 to the preheating section PC. The branch injection hole 44a is fluidly connected to the flow path 42 to which the first mixed gas is supplied. Therefore, the branch injection hole 44a injects the first mixed gas into the preheating section PC. That is, in this embodiment, the first mixed gas is injected into both the combustion space S and the preheating section PC. In this embodiment, the branch injection hole 44a injects the first mixed gas in the axial direction.

[0088] 9, the branch injection holes 44a are arranged radially outward from the central protrusion 46. The branch injection holes 44a are arranged spaced apart from one another in the circumferential direction. The branch injection holes 43a and the branch injection holes 44a are arranged alternately in the circumferential direction.

[0089] Next, the operation of the radiant burner 100D will be described.

[0090] 8, a first mixed gas containing ammonia is supplied to the flow path 42. A portion of the first mixed gas passes through the branch flow path 45a and is injected into the combustion space S from the branch injection hole 43a toward the surface 11 of the burner tile 1 (not shown in FIG. 8).

[0091] The remainder of the first mixed gas is injected into the preheating section PC from the branch injection holes 44a. The nozzle 2 is configured so that the first mixed gas is ignited in the preheating section PC. Therefore, a preheating flame PF is formed in the preheating section PC. For example, in this embodiment, factors such as the flow rate and composition of the first mixed gas may be adjusted so that the first mixed gas is ignited in the preheating section PC. Also, for example, the dimensions of the preheating section PC may be designed so that the first mixed gas having an intended flow rate and composition is ignited in the preheating section PC. In this embodiment, the preheating flame PF is formed along the axial direction. The combustion gas in the preheating section PC is discharged into the combustion space S.

[0092] The wall of the rib 47 surrounding the preheating section PC is heated by the preheating flame PF. As described above, the branch flow path 45a is adjacent to the preheating section PC across the wall of the rib 47. Therefore, the first mixed gas flowing through the branch flow path 45a is heated by the wall of the rib 47. Since the first mixed gas is heated, the combustibility of ammonia in the first mixed gas is improved. As a result, the combustibility of the first mixed gas is improved.

[0093] Referring to FIG. 6 , the first mixture gas injected into the combustion space S is heated and ignited by the surface 11. Therefore, a main flame F is formed in the combustion space S along the surface 11. As described above, the combustibility of the first mixture gas is improved, making the first mixture gas more likely to ignite. For example, in this embodiment, factors such as the flow rate and composition of the first mixture gas may be adjusted so that the first mixture gas ignites in a region along the surface 11. Because the unburned gas temperature of the first mixture gas increases, the temperature of the main flame F increases. As a result, the surface 11 is heated to a higher temperature. Furthermore, because the combustibility of the first mixture gas is improved, the amount of unburned ammonia is reduced. As a result, the phenomenon of unburned ammonia cooling the surface 11 is suppressed, and the surface 11 is heated to a higher temperature. Therefore, the performance of the radiant burner 100D is improved. Furthermore, because the required heat can be supplemented by the heat from preheating in addition to the combustion heat of the first mixture gas, the flow rate of the first mixture gas into the combustion space S can be reduced. As a result, the main flame F is likely to be formed at the intended position.

[0094] The radiant burner 100D as described above can achieve the same effects as the radiant burner 100 according to the first embodiment.

[0095] In particular, in the radiant burner 100D, the nozzle 2 extends along the central axis X, the preheating space P includes a plurality of preheating sections PC, the flow path 45 includes a plurality of branch flow paths 45a, and the plurality of preheating sections PC and the plurality of branch flow paths 45a are arranged alternately around the central axis X. For example, the nozzle 2 having such a configuration can be formed from a single tube 41. Therefore, the nozzle 2 according to this embodiment can be formed more easily than the nozzle 2 according to the first embodiment, which includes the tubes 21 and 22.

[0096] FIG. 10 is a schematic enlarged cross-sectional view showing a radiant burner 100E according to the sixth embodiment. FIG. 11 is a schematic enlarged front view showing the radiant burner 100E of FIG. 10. The burner tile 1 of the radiant burner 100E is the same as the burner tile 1 of the radiant burner 100D according to the fifth embodiment. Therefore, for better understanding, FIGS. 10 and 11 show only the nozzle 2, and the burner tile 1 is omitted. Referring to FIG. 10, the radiant burner 100E differs from the radiant burner 100D according to the fifth embodiment in the orientation of the branch injection holes (second branch fuel injection holes) 44a. In other respects, the radiant burner 100E may be the same as the radiant burner 100D.

[0097] Specifically, in this embodiment, the branch injection holes 44a extend in the radial direction. The branch injection holes 44a are formed on the side surface of the central protrusion 46, which is one of the surfaces defining the preheating section PC. The branch injection holes 44a penetrate the wall of the central protrusion 46 from the flow path 42 to the preheating section PC. The branch injection holes 44a are fluidly connected to the flow path 42 to which the first mixed gas is supplied. Therefore, the branch injection holes 44a inject the first mixed gas into the preheating section PC. In this embodiment, the branch injection holes 44a inject the first mixed gas in the radial direction. Therefore, the preheating flame PF is formed along the radial direction.

[0098] 11, the branch injection holes 44a are arranged spaced apart from one another in the circumferential direction. The branch injection holes 43a and the branch injection holes 44a are arranged alternately in the circumferential direction.

[0099] The radiant burner 100E as described above can achieve the same effects as the radiant burner 100D according to the fifth embodiment.

[0100] FIG. 12 is a schematic enlarged cross-sectional view showing a radiant burner 100F according to the seventh embodiment. FIG. 13 is a schematic enlarged front view showing the radiant burner 100F of FIG. 12. The burner tile 1 of the radiant burner 100F is the same as the burner tile 1 of the radiant burner 100D according to the fifth embodiment. Therefore, for better understanding, FIGS. 12 and 13 show only the nozzle 2, and the burner tile 1 is omitted. Referring to FIG. 12, the radiant burner 100F differs from the radiant burner 100D according to the fifth embodiment in that the radiant burner 100F uses a diffusion method. In other respects, the radiant burner 100F may be the same as the radiant burner 100D.

[0101] Specifically, in this embodiment, the nozzle 2 includes a tube (fifth tube) 51 and a plurality of tubes (sixth tubes) 61 .

[0102] The tube 51 has a generally cylindrical or tubular shape. In this embodiment, the tube 51 is arranged concentrically with the tube 41. The outer diameter of the tube 51 is smaller than the inner diameter of the central protrusion 46. The tube 51 is inserted into the tube 41.

[0103] The radial gaps between the tube 41 and the tubes 51 and 61 function as flow paths (first oxidant flow path, second oxidant flow path) 42. An oxidant (for example, air) is supplied to the flow paths 42.

[0104] The inside of the pipe 51 functions as a flow path (first fuel flow path) 52. The first fuel is supplied to the flow path 52.

[0105] The end of the tube 51 is attached to the central protrusion 46. A plurality of branch tubes 53 extend radially outward from the end of the tube 51. The branch tubes 53 pass through the above-mentioned branch flow passage 45a. The outer diameter of the branch tubes 53 is smaller than the inner diameter of the branch flow passage 45a. Therefore, the oxidizer is supplied from the flow passage 42 to the gap between the branch tubes 53 and the branch flow passage 45a. The branch injection holes 43a (the gaps between the branch injection holes 43a and the branch tubes 53) fluidly communicate with the branch flow passage 45a inject the oxidizer into the combustion space S.

[0106] The inside of the branch pipe 53 functions as a branch flow path (first branch fuel flow path) 54. The branch flow path 54 is fluidly connected to the flow path 52 to which the first fuel is supplied. Therefore, in this embodiment, the first fuel flow path to which the first fuel is supplied includes a plurality of branch flow paths 54. Referring to Fig. 13 , the plurality of preheating sections PC and the plurality of branch flow paths 54 are arranged alternately around the central axis X.

[0107] The radially outer end of the branch pipe 53 functions as a branch injection hole (first branch fuel injection hole) 55. The branch injection hole 55 injects the first fuel into the combustion space S.

[0108] The branch injection hole 43a that injects the oxidizer faces the area (the space around the bottom of the recess 14) that faces the branch injection hole 55 that injects the first fuel.

[0109] 12 , the pipe 61 has a generally cylindrical or tubular shape. The pipe 61 is provided for each branch injection hole 44a. The outer diameter of the pipe 61 is smaller than the diameter of the branch injection hole 44a. The pipe 61 extends axially within the pipe 41 and is inserted into the branch injection hole 44a. The branch injection hole 44a (the gap between the branch injection hole 44a and the pipe 41), which is in fluid communication with the flow path 42, injects oxidizer into the preheating section PC.

[0110] The inside of the tube 61 functions as a branch flow path (second branch fuel flow path) 62. The branch flow path 62 is supplied with the second fuel. Therefore, in this embodiment, the second fuel flow path to which the second fuel is supplied includes multiple branch flow paths 62. The end of the tube 61 is flush with the surface of the tube 41 that defines the preheating section PC. The end of the tube 61 functions as a branch injection hole (second branch fuel injection hole) 63. The branch injection hole 63 injects the second fuel into the preheating section PC. The branch injection hole 63 injects the second fuel in the axial direction. Referring to FIG. 13 , the multiple branch injection holes 55 and the multiple branch injection holes 63 are arranged alternately around the central axis X.

[0111] 12 , in this embodiment, only the oxidizer is supplied to the flow path 42. Therefore, the branch injection hole 43a fluidly connected to the flow path 42 injects only the oxidizer into the combustion space S. Only the first fuel is supplied to the flow path 52. Therefore, the branch injection hole 55 fluidly connected to the flow path 52 injects only the first fuel into the combustion space S. Both the branch injection hole 43a and the branch injection hole 55 face the space around the bottom of the recess 14. Therefore, the first fuel and the oxidizer are mixed in this space and then burned (diffusion method).

[0112] As described above, in this embodiment, only the oxidizer is supplied to the flow path 42. Therefore, the branch injection hole 44a, which is fluidly connected to the flow path 42, injects only the oxidizer into the preheating section PC. Only the second fuel is supplied to the branch flow path 62. Therefore, the branch injection hole 63, which is fluidly connected to the branch flow path 62, injects only the second fuel into the preheating section PC. Both the branch injection hole 44a and the branch injection hole 63 face the preheating section PC. Therefore, the second fuel and the oxidizer are mixed in the preheating section PC and then combusted (diffusion method).

[0113] The radiant burner 100F as described above can achieve the same effects as the radiant burner 100D according to the fifth embodiment.

[0114] In particular, in the radiant burner 100F, the nozzle 2 includes a branch injection hole 43a for injecting the oxidizer, which faces the area facing the branch injection hole 55 for injecting the first fuel, and a branch injection hole 44a for injecting the oxidizer, which faces the area facing the branch injection hole 63 for injecting the second fuel (diffusion type). This configuration prevents the risk of the preheated first fuel igniting inside the nozzle and damaging the nozzle. It also makes it easier to ensure flame stability against load fluctuations.

[0115] Although the embodiments have been described above with reference to the accompanying drawings, the present disclosure is not limited to the above-described embodiments. It is clear that a person skilled in the art can conceive of various modifications or alterations within the scope of the claims, and it is understood that such modifications also fall within the technical scope of the present disclosure.

[0116] For example, in the radiant burner 100D according to the fifth embodiment (FIGS. 6 to 9), the radiant burner 100E according to the sixth embodiment (FIGS. 10 and 11), and the radiant burner 100F according to the seventh embodiment (FIGS. 12 and 13), the catalyst C is not provided in the branch flow passage 45a or the branch flow passage 54 adjacent to the preheating section PC across the wall of the rib 47. However, in other embodiments, the catalyst C may be provided in the branch flow passage 45a or the branch flow passage 54.

[0117] Furthermore, for example, the nozzle 2 may include a swirler (not shown) in any of the flow paths to generate a swirling flow.

[0118] The present disclosure provides ２ It can promote the use of ammonia, which leads to reduced emissions, thereby contributing, for example, to Sustainable Development Goal (SDG) 7 "Ensure access to affordable, reliable, sustainable and modern energy" and SDG 13 "Take urgent action to combat climate change and its impacts".

[0119] DESCRIPTION OF SYMBOLS 1 burner tile 2 nozzle 23 flow path (first fuel flow path) 25 injection hole (first fuel injection hole) 26 injection hole (second fuel injection hole) 29 through hole 35 injection hole (first oxidizer injection hole) 36 injection hole (second oxidizer injection hole) 43 injection hole (first fuel injection hole) 43a branch injection hole (first branch fuel injection hole) 44 injection hole (second fuel injection hole) 45 flow path (first fuel flow path) 45a branch flow path (first branch fuel flow path) 52 flow path (first fuel flow path) 54 branch flow path (first branch fuel flow path) 55 branch injection hole (first branch fuel injection hole) 100 radiant burner 100A radiant burner 100B radiant burner 100C radiant burner 100D radiant burner 100E radiant burner 100F Radiant burner C Catalyst P Preheating space PC Preheating section S Combustion space X Central axis

Claims

1. A radiant burner comprising: a burner tile; and a nozzle protruding from the burner tile toward a combustion space, the nozzle including: a first fuel injection hole for injecting a first fuel containing ammonia into the combustion space; a first fuel flow path in fluid communication with the first fuel injection hole; a preheating space separated from the first fuel injection hole and the first fuel flow path by a wall and adjacent to the first fuel flow path across the wall; and a second fuel injection hole opening into the preheating space for injecting a second fuel into the preheating space.

2. A radiant burner as described in claim 1, wherein a first mixed gas of the first fuel and oxidizer is supplied to the first fuel flow passage, and a second mixed gas of the second fuel and oxidizer is supplied to the second fuel injection hole.

3. A radiant burner as described in claim 1, wherein the nozzle includes: a first oxidizer injection hole facing the area opposite the first fuel injection hole and injecting an oxidizer; and a second oxidizer injection hole facing the area opposite the second fuel injection hole and injecting an oxidizer.

4. A radiant burner as claimed in any one of claims 1 to 3, wherein the nozzle includes a catalyst arranged in the first fuel flow passage at a position adjacent to the preheating space across the wall.

5. A radiant burner as described in any one of claims 1 to 3, wherein the nozzle extends along a central axis, the preheating space is disposed on the central axis, and the first fuel flow passage is disposed outside the preheating space around the central axis so as to surround the preheating space.

6. A radiant burner as described in claim 4, wherein the nozzle extends along a central axis, the preheating space is disposed on the central axis, and the first fuel flow passage is disposed outside the preheating space around the central axis so as to surround the preheating space.

7. A radiant burner as described in claim 5, wherein the preheating space opens into the combustion space on the central axis, and the nozzle extends from the preheating space to the combustion space in a direction intersecting the central axis and includes a through hole penetrating the first fuel flow path.

8. A radiant burner as described in claim 6, wherein the preheating space opens into the combustion space on the central axis, and the nozzle extends from the preheating space to the combustion space in a direction intersecting the central axis and includes a through hole penetrating the first fuel flow path.

9. A radiant burner as described in any one of claims 1 to 3, wherein the nozzle extends along a central axis, the preheating space includes a plurality of preheating sections, the first fuel flow passage includes a plurality of first branch fuel flow passages, and the plurality of preheating sections and the plurality of first branch fuel flow passages are alternately arranged with each other around the central axis.

10. The radiant burner according to claim 4, wherein the nozzle extends along a central axis, the preheating space includes a plurality of preheating sections, the first fuel flow passage includes a plurality of first branch fuel flow passages, and the plurality of preheating sections and the plurality of first branch fuel flow passages are alternately arranged around the central axis.

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