Radiation burner

Abstract

A radiation burner (100) is provided with a burner block (1) and a nozzle (2) protruding in a first direction (D1) from the burner block (1) toward a combustion space (S), the nozzle (2) including a first injection hole (24) for injecting an ammonia-containing gas into the combustion space (S), the first injection hole (24) being disposed at a position away from a surface (11) of the burner block (1) and opening in the first direction (D1). The nozzle (2) includes a swirler (22) that imparts a swirling flow centered on a first direction (D1) to the gas injected from the first injection hole (24).

Description

Technical Field

[0001] The present disclosure relates to a radiant burner. This application claims the benefit of priority based on Japanese Patent Application No. 2022-196869 filed on December 9, 2022, and the contents thereof are cited in this application. Background Art

[0002] The radiation burner heats the surface of the burner brick by the combustion of fuel, and heats the object by the radiation heat from the heated surface. For example, Patent Document 1 discloses such a radiation burner. In the radiation burner, the ejection hole of the mixed gas of fuel and air is arranged at a position away from the bottom of the cup. A collision plate is arranged in a manner opposite to the ejection hole. The collision plate changes the direction of the mixed gas from the ejection hole. The mixed gas is guided radially outward toward the surface of the cup by the collision plate. According to such a structure, the mixed gas collides with the surface of the cup and decelerates. Therefore, it takes a longer time until the mixed gas collides with the surface of the cup again. The mixed gas is fully heated and burned during this period. According to such a structure, when using a fuel with a slower combustion speed such as natural gas or liquefied petroleum gas, the problem of insufficient fuel combustion is solved.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Utility Model Application Laid-Open No. 51-58438 Summary of the invention

[0006] Problems to be solved by the invention

[0007] Ammonia is known as a fuel that does not release CO2. However, the combustion rate of ammonia is slower than that of natural gas. Therefore, when ammonia is used in a radiant burner, unburned ammonia caused by insufficient combustion may become a problem.

[0008] An object of the present disclosure is to provide a radiant burner capable of reducing unburned ammonia when using ammonia as fuel.

[0009] Solutions to Solve Problems

[0010] A radiation burner according to one embodiment of the present invention comprises a burner brick and a nozzle protruding from the burner brick toward a combustion space along a first direction, the nozzle comprising a first injection hole for injecting ammonia-containing gas into the combustion space, the first injection hole being arranged at a position away from a surface of the burner brick and opening toward the first direction, the nozzle comprising a swirler for imparting a swirling flow centered on the first direction to the gas injected from the first injection hole.

[0011] The burner brick may include a recessed portion opened in the first direction as the combustion space, the nozzle may protrude into the recessed portion, and the first injection hole may be arranged at a position away from the bottom of the recessed portion.

[0012] The recess may also have a hemispherical shape.

[0013] The nozzle may include a second injection hole for injecting the ammonia-containing gas into the combustion space, the second injection hole being arranged at a position away from the surface of the burner brick and opening in a second direction intersecting the first direction.

[0014] The nozzle may include a flow path fluidly connected to the first injection hole and a rod disposed in the flow path and supporting the swirler. The rod may protrude from the first injection hole into the combustion space, or may face the combustion space via the first injection hole.

[0015] The effects of the invention are as follows.

[0016] According to the present disclosure, when ammonia is used as a fuel in a radiant burner, unburned ammonia can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] FIG1 is a schematic cross-sectional view showing a radiant burner according to a first embodiment.

[0018] FIG. 2 is a schematic front view showing the radiant burner of FIG. 1 .

[0019] FIG. 3 is a cross-sectional view schematically showing the flow of a mixed gas flowing in the radiant burner of FIG. 1 .

[0020] FIG. 4 is a schematic cross-sectional view showing a radiant burner according to a second embodiment.

[0021] FIG. 5 is a cross-sectional view schematically showing the flow of the mixed gas flowing in the radiant burner of FIG. 4 .

[0022] FIG6 is a schematic cross-sectional view showing a radiant burner according to a third embodiment. DETAILED DESCRIPTION

[0023] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. The specific dimensions, materials, and numerical values ​​shown in these embodiments are merely examples for facilitating understanding, and do not limit the present disclosure unless otherwise specified. In addition, in this specification and the accompanying drawings, elements having substantially the same function and structure are marked with the same symbols, thereby omitting repeated descriptions, and omitting illustrations of elements that are not directly related to the present disclosure.

[0024] 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 .

[0025] 1 , the radiant burner 100 heats the surface 11 of the burner brick 1 by combustion of a mixed gas of ammonia and air, and heats an object (not shown) arranged at a position away from the radiant burner 100 by radiant heat from the heated surface 11. For example, the radiant burner 100 includes a burner brick 1 and a nozzle 2. The radiant burner 100 may also include other components.

[0026] The burner brick 1 is formed of a refractory material such as a ceramic molded product. In the present embodiment, the burner brick 1 has a substantially rectangular parallelepiped shape. The burner brick 1 is not limited thereto and may have other shapes. The burner brick 1 includes a front face 12 arranged to face an object and a back face 13 on the opposite side of the front face 12.

[0027] In the present embodiment, the burner brick 1 includes a recess 14 at the front 12. The recess 14 is formed from the front 12 toward the back 13. The recess 14 is demarcated by the surface 11. The recess 14 is used as a combustion space S. In the present disclosure, "combustion space" refers to a space where a mixture of fuel and air is burned. In the present embodiment, the recess 14 has a hemispherical shape. In other embodiments, the recess 14 may also have other shapes such as a cylindrical shape or a polygonal shape. The recess 14 opens in a first direction D1. In the present disclosure, the first direction D1 can also be referred to as the "central axis direction". In other embodiments, the burner brick 1 may not include the recess 14.

[0028] In the present disclosure, the burner brick 1 is also referred to as a “radiant cup.” And, in the present disclosure, the radiant burner 100 can also be referred to as a “radiant cup burner.”

[0029] The nozzle 2 protrudes from the burner brick 1 toward the combustion space S along the first direction D1. The nozzle 2 sprays the ammonia-containing fuel into the combustion space S. In the present embodiment, the nozzle 2 sprays a mixed gas of ammonia and air into the combustion space S (premixing method). The radiation burner 100 is not limited to the premixing method, but may also be a diffusion method. The nozzle 2 includes a housing 21, a swirler 22, and a rod 23.

[0030] The housing 21 has a generally cylindrical or tubular shape. The housing 21 is mounted on the burner brick 1 in such a manner that the central axis thereof is parallel to the first direction D1. The housing 21 is located at the center of the hemispherical recess 14. The housing 21 penetrates the wall of the burner brick 1 from the back surface 13 and protrudes into the recess 14. In the present disclosure, the "central axis direction", "radial direction" and "circumferential direction" of the housing 21 can be simply referred to as the "central axis direction", "radial direction" and "circumferential direction".

[0031] The housing 21 includes a first injection hole 24. The first injection hole 24 injects the mixed gas into the combustion space S. The first injection hole 24 is located at the protruding end of the housing 21. That is, the first injection hole 24 is arranged at a position away from the surface 1. Specifically, in the present embodiment, the first injection hole 24 is located in the combustion space S and is arranged at a position away from the bottom of the recess 14. The first injection hole 24 opens toward the first direction D1. The first injection hole 24 has a circular shape.

[0032] The inner wall of the housing 21 defines a flow path 25 for the mixed gas. The flow path 25 is in fluid communication with the first injection hole 24. The flow path 25 has a substantially cylindrical shape.

[0033] In the present embodiment, the housing 21 includes a throttle portion 26. The throttle portion 26 reduces the cross-sectional area of ​​the flow path 25 at a portion of the flow path 25. The throttle portion 26 protrudes radially inward from the inner wall defining the flow path 25. The throttle portion 26 has a ring shape. In the present embodiment, the throttle portion 26 is arranged between the first injection hole 24 and the swirler 22. In other embodiments, the housing 21 may not include the throttle portion 26.

[0034] The swirler 22 imparts a swirling flow centered in the first direction D1 to the mixed gas injected from the first injection hole 24. The swirler 22 is disposed in the flow path 25. The swirler 22 is supported by the rod 23. Referring to FIG. 2 , for example, the swirler 22 includes a plurality of blades protruding radially outward from the rod 23. For example, the swirler 22 and the rod 23 are relatively fixed to the housing 21. The swirler 22 changes the flow direction of the mixed gas while the mixed gas passes between the blades, thereby imparting a swirling flow to the mixed gas.

[0035] 1 , the rod 23 is disposed in the flow path 25 on the central axis of the housing 21. The rod 23 extends along the central axis of the housing 21. In the present embodiment, the rod 23 protrudes into the combustion space S beyond the first injection hole 24. That is, in the present embodiment, the protruding end 23a of the rod 23 is located in the combustion space S. In other embodiments, the rod 23 may not protrude into the combustion space S from the first injection hole 24.

[0036] Next, the operation of the radiant burner 100 will be described.

[0037] Fig. 3 is a cross-sectional view schematically showing the flow of the mixed gas F, F1, and F2 flowing in the radiant burner 100 of Fig. 1. In the nozzle 2, the mixed gas F flows in the flow path 25. The swirler 22 imparts a swirling flow to the mixed gas F. The flow of the swirling mixed gas F is throttled by the throttle portion 26. As a result, the flow velocity of the mixed gas F is increased, and the flow unevenness of the mixed gas F is reduced.

[0038] The first injection hole 24 injects the swirling mixed gas F into the combustion space S. The mixed gas F flows radially outward due to the centrifugal force generated by the swirling. A portion F1 of the mixed gas injected from the first injection hole 24 flows along the surface 11. The pressure in the central area of ​​the combustion space S, more specifically, the pressure around the protrusion 23a, is lower than the pressure in the surrounding area. Therefore, the flow direction of the mixed gas F1 changes from the radial outside to the radial inside, and further flows toward the protrusion 23a along the center axis. The mixed gas F1 ignites with the protrusion 23a as a starting point, and is fully heated and burned before changing the direction of flow. The high-temperature combustion gas flows toward the protrusion 23a. Near the protrusion 23a, the high-temperature combustion gas contributes to the heating of the injected mixed gas F1.

[0039] Furthermore, the pressure of the area between the first injection hole 24 and the surface 11 around the nozzle 2 is also lower than the pressure of the surrounding area. Therefore, the remaining part F2 of the mixed gas injected from the first injection hole 24 flows toward this space. The mixed gas F2 forms a circulation flow along the surface 11 around the nozzle 2. Since the surface 11 is heated by the flame, the mixed gas F2 is fully heated by the surface 11 during the circulation. A part of the heated mixed gas F2 merges with the mixed gas F1. Therefore, the mixed gas F can be fully heated.

[0040] According to the above structure, the mixed gas F can be burned at a desired position in the combustion space S. In addition, since the mixed gas F can be burned at a desired position in the combustion space S, the surface 11 can be heated sufficiently as expected. Furthermore, since the mixed gas F is heated sufficiently, the mixed gas F is burned sufficiently. Therefore, the unburned ammonia in the exhaust gas can be reduced.

[0041] The above-mentioned radiation burner 100 includes a burner brick 1 and a nozzle 2 protruding from the burner brick 1 toward the combustion space S in the first direction D1. The nozzle 2 includes a first injection hole 24 for injecting a mixed gas containing ammonia into the combustion space S. The first injection hole 24 is arranged at a position away from the surface 11 of the burner brick 1 and opens toward the first direction D1. In addition, the nozzle 2 includes a swirler 22 for imparting a swirling flow centered on the first direction D1 to the mixed gas F injected from the first injection hole 24. According to such a structure, as described above, the pressure of the area between the first injection hole 24 and the surface 11 around the nozzle 2 is lower than the pressure of the surrounding area. Therefore, a circulating flow of the mixed gas F2 along the surface 11 is formed around the nozzle 2. Since the surface 11 is heated by the flame, the mixed gas F2 is fully heated by the surface 11 during the circulation. Therefore, the mixed gas F can be fully heated. As a result, problems such as insufficient heating of the surface 11 and increase of unburned ammonia in the exhaust gas can be suppressed.

[0042] Furthermore, the burner brick 1 includes a recess 14 opening toward a first direction D1 as a combustion space S, the nozzle 2 protrudes into the recess 14, and the first injection hole 24 is arranged at a position away from the bottom of the recess 14. According to such a structure, the flow of the mixed gases F1 and F2 is surrounded by the recess 14. Therefore, a circulating flow can be easily formed. In addition, in the case where the mixed gas cannot burn at the expected position due to insufficient heating, there is a concern that the flame will fly out of the recess 14. This is called rising. According to the above structure, since the mixed gas F can be burned at the expected position in the combustion space S, the rising of the flame can be suppressed.

[0043] Furthermore, the recessed portion 14 has a hemispherical shape. With such a structure, the mixed gases F1 and F2 can flow smoothly along the hemispherical shape, thereby making it easier to form a circulation flow.

[0044] Furthermore, the nozzle 2 includes a rod 23 disposed in the flow path 25 and supporting the swirler 22, and the rod 23 protrudes from the first injection hole 24 into the combustion space S. According to such a structure, since the combustion gas returned from the surface 11 to the central area merges with the injected mixed gas F1, the protruding end 23a of the rod 23 functions as a starting point for ignition. Therefore, the mixed gas F1 can be burned well.

[0045] Next, a radiant burner according to another embodiment will be described.

[0046] 4 is a schematic cross-sectional view showing a radiant burner 200 according to a second embodiment. The radiant burner 200 differs from the radiant burner 100 according to the first embodiment in that the nozzle 2 further includes a plurality of second injection holes 27. The radiant burner 200 may be the same as the radiant burner 100 in other configurations.

[0047] The housing 21 includes a plurality of second injection holes 27. The number of the second injection holes 27 may be two, three, four, five, or more than five. For example, the plurality of second injection holes 27 are evenly arranged along the circumferential direction. The second injection holes 27 inject the mixed gas into the combustion space S.

[0048] For example, the second injection hole 27 is located between the first injection hole 24 and the swirler 22 in the first direction D1. Specifically, in the present embodiment, the second injection hole 27 is formed in the throttle portion 26. In other embodiments, for example, the second injection hole 27 may also be formed at a position upstream or downstream of the throttle portion 26. In addition, the second injection hole 27 is located in the combustion space S and is disposed at a position away from the bottom of the recess 14.

[0049] The second injection hole 27 opens toward a second direction D2 intersecting the first direction D1. In the present embodiment, the second direction D2 is perpendicular to the first direction D1. That is, in the present embodiment, the second direction D2 is equivalent to the radial direction. In other embodiments, the second direction D2 may not be perpendicular to the first direction D1, and may be inclined relative to the radial direction. The second injection hole 27 may also be in various shapes such as a circular shape, an elliptical shape, or a polygonal shape.

[0050] Next, the operation of the radiant burner 200 will be described.

[0051] Fig. 5 is a cross-sectional view schematically showing the flow of the mixed gas F, F3, F4, and F5 flowing in the radiant burner 200 of Fig. 4. In the nozzle 2, the mixed gas F flows in the flow path 25. The swirler 22 imparts a swirling flow to the mixed gas F. The flow of the swirling mixed gas F is throttled by the throttle portion 26. As a result, the flow velocity of the mixed gas F is increased, and the flow unevenness of the mixed gas F is reduced.

[0052] The first injection hole 24 injects a portion F3 of the swirling mixed gas into the combustion space S. The mixed gas F3 flows radially outward due to the centrifugal force generated by the swirling. As described above, the pressure in the central area of ​​the combustion space S, more specifically, the pressure around the protrusion 23a, is lower than the pressure in the surrounding area. Therefore, the flow direction of the mixed gas F3 changes from the radial outside to the radial inside, and further flows toward the protrusion 23a along the central axis. The mixed gas F3 ignites with the protrusion 23a as a starting point, and is fully heated and burned before changing the direction of flow. The high-temperature combustion gas flows toward the protrusion 23a.

[0053] Furthermore, the second injection hole 27 injects the remaining part of the swirling mixed gas F into the combustion space S. A part F4 of the mixed gas forms a flow along the surface 11. Since the surface 11 is heated by the flame, the mixed gas F4 is heated by the surface 11. Similar to the mixed gas F3, the mixed gas F4 forms a circulating flow in which the direction of its flow changes from the radial outside to the radial inside and toward the second injection hole 27. The mixed gas F4 ignites with the vicinity of the second injection hole 27 as a starting point, and is fully heated and burned before changing the direction of the flow. A part of the high-temperature combustion gas flows toward the vicinity of the first injection hole 24, and the remaining part flows toward the vicinity of the second injection hole 27. The high-temperature combustion gas contributes to the heating of the mixed gas F3 injected near the first injection hole 24, and contributes to the heating of the mixed gas F4 injected near the second injection hole 27.

[0054] Furthermore, the pressure of the area between the second injection hole 27 and the surface 11 around the nozzle 2 is also lower than the pressure of the surrounding area. Therefore, the remaining part F5 of the mixed gas injected from the second injection hole 27 flows toward this space. The mixed gas F5 forms a circulation flow along the surface 11 around the nozzle 2. Since the surface 11 is heated by the flame, most of the mixed gas F5 is fully heated by the surface 11 during the circulation. A part of the heated mixed gas F5 merges with the mixed gas F4. Therefore, the mixed gas F can be fully heated.

[0055] Such a radiant burner 200 has substantially the same effect as the radiant burner 100 of the first embodiment. In addition, in the radiant burner 200, the nozzle 2 includes a second injection hole 27 for injecting the mixed gas F into the combustion space S. The second injection hole 27 is arranged at a position away from the bottom of the recess 14 and opens in a second direction D2 perpendicular to the first direction D1. According to such a structure, since the mixed gas is injected from both the first injection hole 24 and the second injection hole 27, the flow rate of the mixed gas is reduced, and the mixed gas stays in the recess 14 for a long time. Therefore, the mixed gas is easily heated and burned sufficiently.

[0056] Next, a radiation burner according to still another embodiment will be described.

[0057] 6 is a schematic cross-sectional view showing a radiant burner 300 of the third embodiment. The radiant burner 300 is different from the radiant burner 200 of the second embodiment in that the nozzle 2 does not include the throttle portion 26 but includes an inner tube 28 and the rod 23 does not protrude from the first injection hole 24 into the combustion space S.

[0058] Specifically, the inner cylinder 28 has a substantially cylindrical shape. The inner cylinder 28 is arranged concentrically with the outer shell 21 on the inner side of the outer shell 21. A gap is formed between the inner surface of the outer shell 21 and the outer surface of the inner cylinder 28. The inner cylinder 28 is arranged at a position upstream of the first injection hole 24. The end of the downstream side of the inner cylinder 28 includes an inner cylinder end 28a that expands in the radial direction. The inner cylinder end 28a is connected to the inner surface of the outer shell 21. For example, the inner cylinder 28 may be formed integrally with the outer shell 21, or may be formed separately from the outer shell 21 and then mounted on the outer shell 21.

[0059] The second injection hole 27 is formed between the upstream and downstream ends of the inner tube 28 in the central axis direction. With such a structure, the inner tube 28 divides a part of the flow path 25 into an inner portion connected to the first injection hole 24 and an outer portion connected to the second injection hole 27.

[0060] The protruding end 23a of the rod 23 is arranged at a position upstream of the first injection hole 24. Therefore, the protruding end 23a faces the combustion space S via the first injection hole 24. Specifically, in the present embodiment, the protruding end 23a is arranged inside the inner tube 28.

[0061] The swirler 22 is disposed inside the inner tube 28. Therefore, in the present embodiment, the swirler 22 imparts a swirling flow to the mixed gas injected from the first injection holes 24.

[0062] The radiant burner 300 may be the same as the radiant burner 200 of the second embodiment in terms of other structures.

[0063] Such a radiant burner 300 has substantially the same effect as the radiant burner 200 of the second embodiment. In addition, in the radiant burner 300, the rod 23 is opposed to the combustion space S via the first injection hole 24. In such a structure, the combustion gas returned from the surface 11 to the central area can contribute to the heating of the mixed gas F1, and the protruding end 23a of the rod 23 functions as the starting point of ignition. Therefore, the mixed gas F1 can be burned well.

[0064] The above embodiments are described with reference to the accompanying drawings, but the present disclosure is not limited to the above embodiments. It is clear that various changes or modifications can be thought of by those skilled in the art within the scope of the claims, and it should be understood that these changes or modifications also belong to the technical scope of the present disclosure.

[0065] For example, in the second and third embodiments, both the first injection hole 24 and the second injection hole 27 are in fluid communication with the flow path 25. In other embodiments, the housing 21 may further include another flow path in fluid communication with only the second injection hole 27.

[0066] Furthermore, for example, in the above-mentioned embodiment, the burner brick 1 includes the recess 14. In other embodiments, for example, the burner brick 1 may not include the recess 14 but may have a flat wall shape or a flat plate shape. In this case, the nozzle 2 protrudes from the flat front face 12 arranged in the burner brick 1 so as to face the object. In this case, the flows of the mixed gases F1 to F5 shown in FIGS. 3 and 5 can also be generated.

[0067] Since the present disclosure can promote the use of ammonia to reduce CO2 emissions, it can contribute to, for example, Goal 7 of the Sustainable Development Goals (SDGs) to "ensure adequate, reliable, sustainable and modern energy" and Goal 13 to "take urgent action to combat climate change and its impacts."

[0068] Explanation of symbols

[0069] 1—burner brick, 2—nozzle, 11—surface, 14—recess, 22—swirler, 23—rod, 24—first injection hole, 25—flow path, 27—second injection hole, 100—radiant burner, 200—radiant burner, 300—radiant burner, D1—first direction, D2—second direction, F, F1~F5—mixed gas (ammonia-containing gas), S—combustion space.

Claims

1. A radiation burner, characterized in that: A burner brick and a nozzle protruding from the burner brick toward the combustion space in a first direction, The nozzle comprises a first injection hole for injecting ammonia-containing gas into the combustion space. The first injection hole is arranged at a position away from the surface of the burner brick and opens toward the first direction. The nozzle includes a swirler that provides a swirling flow centered in the first direction to the gas injected from the first injection hole.

2. The radiant burner according to claim 1, characterized in that The burner brick includes a recessed portion opening toward the first direction as the combustion space. The nozzle protrudes into the recess. The first injection hole is arranged at a position away from the bottom of the recessed portion.

3. The radiant burner according to claim 2, characterized in that The recessed portion has a hemispherical shape.

4. The radiant burner according to any one of claims 1 to 3, characterized in that The nozzle includes a second injection hole for injecting the ammonia-containing gas into the combustion space, the second injection hole being disposed at a position away from the surface of the burner brick and opening in a second direction intersecting the first direction.

5. The radiant burner according to any one of claims 1 to 3, characterized in that The nozzle includes a flow path fluidly connected to the first injection hole and a rod disposed in the flow path and supporting the swirler, wherein the rod protrudes from the first injection hole into the combustion space or faces the combustion space via the first injection hole.

6. The radiant burner according to claim 4, characterized in that The nozzle includes a flow path fluidly connected to the first injection hole and a rod disposed in the flow path and supporting the swirler, wherein the rod protrudes from the first injection hole into the combustion space or faces the combustion space via the first injection hole.

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