Metal heating furnace with regenerative burner

Abstract

The present invention provides a metal heating furnace with a regenerative burner that effectively suppresses the generation of nitrogen oxides by burning the ammonia fuel in a low-oxygen atmosphere without allowing all of it to come into direct contact with air. [Solution] The regenerative burner consists of a combustion air nozzle 33, 34 formed on opposing side walls 13a, 13b, respectively, which supplies combustion air into the furnace body 10, an air port 31, 32 for drawing in exhaust gas from the furnace body 10, and heat exchange chambers 35, 36 which communicate with the air ports 31, 32, respectively, and have a heat storage body that recovers heat from the exhaust gas and preheats the combustion air supplied into the furnace body 10, and a fuel injection nozzle 41 provided on the ceiling wall 12 for supplying ammonia into the furnace body 10, and the central axes L1, L2 of the combustion air nozzles 33, 34 and the central axis L3 of the fuel injection nozzle 41 are arranged so as not to intersect on the same plane.

Description

Technical Field

[0001] The present invention relates to a metal heating furnace with a regenerative burner that uses ammonia as fuel.

Background Art

[0002] Conventionally, a metal heating furnace with a regenerative burner that separately supplies air and fuel into a furnace body and repeatedly performs flame injection and exhaust gas suction at regular intervals has been known. As the fuel, mainly hydrocarbon gases such as natural gas and propane gas have been used.

[0003] Such a conventional metal heating furnace with a regenerative burner, as shown in FIG. 5, in a furnace body 50 having a furnace floor 51, a ceiling wall 52, and side walls 53, air inlets 61 and 62 are formed in the opposing side walls 53, 53, respectively. In addition to the function of combustion air nozzles, the air inlets 61 and 62 are provided with fuel nozzles 63 and 64 for supplying combustion air into the furnace body 50. Further, exhaust gas in the furnace body 50 is sucked from the air inlets 61 and 62. Outside the furnace body 50, heat exchange chambers 65 and 66 having regenerators that communicate with the air inlets 61 and 62 to recover the heat of the exhaust gas and preheat the combustion air supplied into the furnace body 50 are arranged. One combustion blower 67 for supplying combustion air is connected to the heat exchange chambers 65 and 66 via switching valves 67a and 67b, and one exhaust fan 68 for sucking exhaust gas is connected via switching valves 68a and 68b.

[0004] However, since a conventional metal heating furnace with a regenerative burner uses a hydrocarbon gas as fuel, there is a problem that it generates carbon dioxide, which causes global warming.

[0005] In view of such problems, in recent years, ammonia, which does not generate carbon dioxide even when burned, has attracted attention as a new fuel. However, mixing ammonia with fossil fuels or burning only ammonia has an adverse effect on the human body due to nitrogen oxides (NOX It is known that emissions of ) increase, and it is also known that supplying ammonia to a flame produced by burning coal fuel suppresses the generation of nitrogen oxides (see, for example, Patent Document 1). Furthermore, if the air ratio is reduced to reduce the generation of nitrogen oxides, unburned ammonia is emitted.

[0006] The combustion apparatus described in Patent Document 1 is not a regenerative burner type, but in order to solve the problem of increased nitrogen oxides when ammonia is added to coal and burned, it is configured as shown in Figure 6 to suppress the generation of nitrogen oxides.

[0007] In other words, as shown in Figure 6, an ammonia flow path 77 is formed inside the mixed gas flow path 71 of the burner 70, and an ammonia supply means 72 is provided for supplying ammonia to the ammonia flow path 77. Furthermore, the system includes a control means 73 that controls the supply of ammonia according to operating conditions, and a distribution means 75 (and multiple distribution transport paths 76) that distributes the ammonia sent from the ammonia supply means 72 to the input section 74. The control means 73 controls the distribution of ammonia, and ammonia is also supplied from the input section 74. In other words, in this combustion apparatus, ammonia is supplied into the furnace body from both the ammonia flow path 77 and the input section 74. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Patent No. 7020759 [Overview of the project] [Problems that the invention aims to solve]

[0009] In the combustion apparatus described in Patent Document 1, ammonia from the input section 74 can be supplied to a low-oxygen atmosphere gas inside the furnace body and burned, thus suppressing the generation of nitrogen oxides. On the other hand, ammonia supplied from the ammonia flow path 77 located inside the mixed gas flow path 71 is immediately mixed directly with the air supplied from the mixed gas flow path 71 and burned, just as in the conventional technology shown in Figure 5. Therefore, it is not possible to suppress the generation of nitrogen oxides.

[0010] Therefore, the object of the present invention is to provide a product that can effectively suppress the generation of nitrogen oxides in a metal heating furnace with a regenerative burner that uses ammonia as fuel, by burning all of the ammonia used as fuel in a low-oxygen concentration atmospheric gas without bringing it into direct contact with air. [Means for solving the problem]

[0011] To achieve the above objective, the metal heating furnace of the present invention has a furnace body (10) having a hearth (11), a ceiling wall (12), and side walls (13), and uses ammonia as fuel. Combustion air nozzles (33, 34) are formed on opposing side walls (13a, 13b) of the aforementioned side wall (13) and are provided for supplying combustion air into the furnace body (10), and air ports (31, 32) are provided for drawing in exhaust gas from within the furnace body (10), The heat exchange chambers (35, 36) are located outside the furnace body (10), communicate with the air vents (31, 32), and have heat storage bodies that recover heat from the exhaust gas and preheat the combustion air supplied to the furnace body (10). The regenerative burner is provided on the ceiling wall (12) and is equipped with a fuel injection nozzle (41) that supplies ammonia into the furnace body (10), and repeatedly injects a flame and sucks in exhaust gas at regular intervals. The combustion air nozzles (33, 34) and the fuel injection nozzle (41) are arranged such that the central axes (L1, L2) of the combustion air nozzles (33, 34) and the central axis (L3) of the fuel injection nozzle (41) do not intersect on the same plane, and the combustion air supplied from the combustion air nozzles (33, 34) and the ammonia supplied from the fuel injection nozzle (41) do not come into direct contact.

[0012] Furthermore, the present invention is characterized in that the central axes (L1, L2) of the combustion air nozzles (33, 34) provided in the air vents (31, 32) formed in the opposing side walls (13a, 13b) of the side wall (13) coincide and form a straight line. (Yamahiro: Only special cases are claimed; if it doesn't matter whether they coincide or not, it doesn't need to be claimed.)

[0013] Furthermore, the metal heating furnace of the present invention has a furnace body (10) having a hearth (11), a ceiling wall (12), and side walls (13), and uses ammonia as fuel. Combustion air nozzles (33, 34) are formed at intervals on one (13a) of the side wall (13) and are provided for supplying combustion air into the furnace body (10), and air ports (31, 32) are provided for drawing in exhaust gas from inside the furnace body (10), The heat exchange chambers (35, 36) are located outside the furnace body (10), communicate with the air vents (31, 32), and have heat storage bodies that recover heat from the exhaust gas and preheat the combustion air supplied to the furnace body (10). The regenerative burner is provided on the ceiling wall (12) and is equipped with a fuel injection nozzle (41) that supplies ammonia into the furnace body (10), and repeatedly injects a flame and sucks in exhaust gas at regular intervals. The combustion air nozzles (33, 34) and the fuel injection nozzle (41) are arranged such that the central axes (L1, L2) of the combustion air nozzles (33, 34) and the central axis (L3) of the fuel injection nozzle (41) do not intersect on the same plane, and the combustion air supplied from the combustion air nozzles (33, 34) and the ammonia supplied from the fuel injection nozzle (41) do not come into direct contact.

[0014] Furthermore, the present invention is characterized by having only one fuel injection nozzle (41).

[0015] Furthermore, the present invention is characterized by providing a plurality of fuel injection nozzles (41a, 41b, 41c, 41d, 41e).

[0016] The symbols in parentheses above indicate the corresponding elements or items shown in the drawings and the embodiments for carrying out the invention described later. [Effects of the Invention]

[0017] In the metal heating furnace with a regenerative burner of the present invention, the combustion air nozzles provided in air vents formed in opposing side walls and the ammonia-fueled fuel injection nozzles provided in the ceiling wall are arranged such that the central axes of the combustion air nozzles and the central axes of the fuel injection nozzles do not intersect on the same plane. As a result, the ammonia supplied from the fuel injection nozzles can be burned entirely in an atmosphere gas with a low oxygen concentration without directly contacting the air supplied from the combustion air nozzles. Consequently, the generation of nitrogen oxides can be effectively suppressed. Furthermore, since the fuel injection nozzles are installed on the ceiling wall, they do not need to be located in the same position as the combustion air nozzles, which are installed in air vents formed on the opposing side walls, as in conventional examples. Therefore, they do not need to be closed (turned off) at regular intervals and can be used as a common, always open (on) nozzle.

[0018] Further, according to the present invention, the central axes of the combustion air nozzles provided at the air inlets formed in the opposing side walls of the side walls coincide with each other to form a straight line, so that a metal heating furnace with a regenerative burner that is symmetric and balanced can be obtained.

[0019] Further, according to the present invention, the number of fuel injection nozzles may be one or more, but by preventing the ammonia supplied from each fuel injection nozzle from directly contacting the air supplied from the combustion air nozzle, ammonia can be burned in the atmospheric gas while effectively suppressing the generation of nitrogen oxides.

[0020] Further, according to the present invention, in the type of regenerative burner in which air inlets for supplying combustion air and sucking exhaust gas are provided separately on the same side wall of the side wall, a fuel injection nozzle for supplying ammonia is provided on the ceiling wall, and the central axis of the fuel injection nozzle and the central axis of the combustion air nozzle are arranged so as not to intersect on the same plane, so that the ammonia supplied from the fuel injection nozzle does not directly contact the air supplied from the combustion air nozzle, and all of it can be burned in an atmospheric gas with a low oxygen concentration. As a result, the generation of nitrogen oxides can be effectively suppressed. Further, by positioning the central axis of the fuel injection nozzle extending vertically at the central position between the central axes of the combustion air nozzles extending parallel and horizontally, a metal heating furnace with a regenerative burner that is symmetric and balanced can be obtained.

Brief Description of the Drawings

[0021] [Figure 1] It is a side sectional view showing a state in which flames are ejected from one side in a metal heating furnace with a regenerative burner according to an embodiment of the present invention. [Figure 2] It is a side sectional view showing a state in which flames are ejected from the other side in a metal heating furnace with a regenerative burner according to an embodiment of the present invention. [Figure 3] It is a plan view showing a main part of the metal heating furnace with a regenerative burner shown in FIG. 1. [Figure 4]This is a plan view showing the main parts of a metal heating furnace with a regenerative burner according to another embodiment of the present invention. [Figure 5] This is a side cross-sectional view showing a conventional metal heating furnace. [Figure 6] This is a partial side cross-sectional view showing another conventional metal heating furnace. [Figure 7] This is a plan view showing the main parts of a metal heating furnace with a regenerative burner according to yet another embodiment of the present invention. [Modes for carrying out the invention]

[0022] A metal heating furnace with a regenerative burner according to an embodiment of the present invention will be described with reference to Figures 1 to 3.

[0023] As shown in Figures 1 and 3, the metal heating furnace with a regenerative burner according to this embodiment has a furnace body 10 having a hearth 11, a ceiling wall 12, and four side walls 13 (13a, 13b, 13c, 13d), and burns ammonia as fuel. Air and ammonia (fuel) are supplied separately into the furnace body 11, and flame injection and exhaust gas suction are repeated at regular intervals.

[0024] Of the side walls 13 that make up the furnace body 10, air vents 31 and 32 are formed in the opposing side walls 13a (right side in Figures 1 and 3) and 13b (left side in Figures 1 and 3), respectively. Combustion air nozzles 33 and 34 are provided at the air inlets 31 and 32 to supply combustion air into the furnace body 10.

[0025] Combustion air is supplied from the air inlets 31 and 32 via the combustion air nozzles 33 and 34, and exhaust gas from inside the furnace body 50 is drawn in. In a metal heating furnace with a regenerative burner, when combustion air is supplied from one (right) air inlet 31, exhaust gas is drawn out to the outside from the other (left) air inlet 32, and conversely, when combustion air is supplied from the other (left) air inlet 32, exhaust gas is drawn out to the outside from one (right) air inlet 31.

[0026] Outside the furnace body 10, there are heat exchange chambers 35 and 36, which are connected to air inlets 31 and 32 and have heat storage bodies that recover heat from exhaust gases and preheat the combustion air supplied into the furnace body 10. In the heat exchange chambers 35 and 36, a combustion blower 47 is connected via switching valves 47a and 47b to supply combustion air, and an exhaust fan 48 is connected via switching valves 48a and 48b to draw in exhaust gas.

[0027] Furthermore, the ceiling wall 12 is equipped with multiple fuel injection nozzles 41 (41a, 41b, 41c, 41d, 41e), five in this case, for supplying ammonia into the reactor body 10. Each fuel injection nozzle 41 (41a, 41b, 41c, 41d, 41e) is positioned facing downwards, and ammonia is injected vertically along the central axis L3 of each fuel injection nozzle 41. Ammonia is supplied from the ammonia supply device 20 to each fuel injection nozzle 41 via an on-off valve 42.

[0028] As shown in Figure 3, in the relationship between the two combustion air nozzles 33 and 34 that extend horizontally opposite each other (left and right in Figure 3) and the five fuel injection nozzles 41 (41a, 41b, 41c, 41d, 41e), the central axes L1 and L2 of the two combustion air nozzles 33 and 34 and the central axis L3 of each fuel injection nozzle 41 are arranged so that they do not intersect on the same plane. Specifically, in a plan view, three of the five fuel injection nozzles 41 (41a, 41b, 41c, 41d, 41e) are located on the side wall 13 (13c) side (upper side in Figure 3) of the central axes L1 and L2 of the combustion air nozzles 33 and 34, and the remaining two (41b, 41d) are located on the side wall 13 (13d) side (lower side in Figure 3) of the central axes L1 and L2 of the combustion air nozzles 33 and 34.

[0029] The central axis L1 of the combustion air nozzle 33 is a virtual axis extending parallel to the direction in which the combustion air nozzle 33 extends, from the radial center of the combustion air nozzle 33, and the central axis L2 of the combustion air nozzle 34 is a virtual axis extending parallel to the direction in which the combustion air nozzle 34 extends, from the radial center of the combustion air nozzle 34. Here, the central axis L1 of the combustion air nozzle 33 and the central axis L2 of the combustion air nozzle 34 are positioned to coincide and form a straight line. Similarly, the central axis L3 of each fuel injection nozzle 41 (41a, 41b, 41c, 41d, 41e) is a virtual axis that extends parallel to the direction in which the fuel injection nozzle 41 extends, from the radial center of each fuel injection nozzle 41.

[0030] In this embodiment, combustion using a metal heating furnace with a regenerative burner is performed by turning on the switching valve 47a of the combustion blower 47 and turning off the switching valve 47b, as shown in Figure 1, while turning off the switching valve 48a of the exhaust fan 48 and turning on the switching valve 48b. As a result, combustion air is sent from the combustion blower 47 to the heat exchange chamber 35 and injected from the combustion air nozzle 33. At this time, ammonia is injected as fuel from each fuel injection nozzle 41 (41a, 41b, 41c, 41d, 41e), so flame F1 is injected from the air inlet 31 toward the inside of the furnace body 10, and the exhaust gas at that time is sent to the heat exchange chamber 36 via the combustion air nozzle 34, sucked up by the exhaust fan 48 and expelled to the outside.

[0031] After a certain period of time has elapsed, as shown in Figure 2, the switching valve 47a of the combustion blower 47 is turned OFF, the switching valve 47b is turned ON, and the switching valve 48a of the exhaust fan 48 is turned ON, and the switching valve 48b is turned OFF. As a result, combustion air is sent from the combustion blower 47 to the heat exchange chamber 36 and injected from the combustion air nozzle 34. At this time, ammonia is injected as fuel from each fuel injection nozzle 41 (41a, 41b, 41c, 41d, 41e), so flame F2 is injected from the air inlet 32 ​​toward the inside of the furnace body 10, and the exhaust gas at that time is sent to the heat exchange chamber 35 via the combustion air nozzle 33, sucked up by the exhaust fan 48 and expelled to the outside.

[0032] In this manner, the injection of flame F1 from air port 31 and the injection of flame F2 from air port 32 are repeated alternately as a certain period of time elapses, and the suction of exhaust gas is also repeated accordingly. According to this, in any case, it is not necessary to close (turn off) the five fuel injection nozzles 41 (41a, 41b, 41c, 41d, 41e) at regular intervals, and they can be used as a common unit, always in an open (on) state. Therefore, the number of fuel injection nozzles 41 can be halved compared to the conventional example (Figure 5). In other words, in the conventional example (Figure 5), a combustion nozzle 63 was provided at the air port 61 and a combustion nozzle 64 at the air port 62, but in this embodiment, as shown in Figure 4, only one fuel injection nozzle 41 for ammonia ejection is provided in the center of the furnace body 10 (however, the central axes L1 and L2 of the combustion air nozzles 33 and 34 and the central axis L3 of the fuel injection nozzle 41 are arranged so as not to intersect on the same plane), and it can be used in an open (on) state at all times. Furthermore, if multiple fuel injection nozzles 41 are provided, the amount of ammonia injected may be kept constant, but it is possible to control it in various ways, such as partially changing the amount of ammonia injected or partially not injecting it.

[0033] As described above, in the metal heating furnace with a regenerative burner according to this embodiment, the central axis L3 of each fuel injection nozzle 41 (41a, 41b, 41c, 41d, 41e), which extends vertically from the ceiling wall 12 of the furnace body 10, is arranged so that it does not intersect with the central axis L1 of the combustion air nozzle 33, which extends horizontally from the side surface 13 (13a) of the furnace body 10, and the central axis L2 of the combustion air nozzle 34, which extends horizontally from the side surface 13 (13b) of the furnace body 10, on the same plane. Therefore, the ammonia supplied (injected) from each fuel injection nozzle 41 does not come into direct contact with the air supplied from the combustion air nozzles 33 and 34, and all of the injected ammonia can be burned in a low-oxygen atmosphere gas. As a result, the generation of nitrogen oxides can be reliably suppressed.

[0034] In the metal heating furnace with regenerative burner shown in Figure 3 according to the above embodiment, three of the five fuel injection nozzles 41 (41a, 41b, 41c, 41d, 41e) are located on the side wall 13 (13c) side (upper side in Figure 3) of the central axes L1, L2 of the combustion air nozzles 33, 34, and the remaining two (41b, 41d) are located on the side wall 13 (13d) side (lower side in Figure 3) of the central axes L1, L2 of the combustion air nozzles 33, 34. However, the configuration is not limited to this. Therefore, for example, as shown in Figure 1, all five fuel injection nozzles 41 can be positioned on the side wall 13 (13c) side (upper side in Figure 3) or the side wall 13 (13d) side (lower side in Figure 3) of the central axes L1 and L2 of the combustion air nozzles 33 and 34.

[0035] Furthermore, the number of nozzles is not limited. For example, as shown in Figure 4, only one fuel injection nozzle 41 can be provided, and it can be positioned on the side wall 13 (13c) side (upper side in Figure 3) or the side wall 13 (13d) side (lower side in Figure 3) of the central axes L1 and L2 of the combustion air nozzles 33 and 34. Therefore, it is possible to provide six or more fuel injection nozzles 41, and their arrangement can be set as appropriate, as long as the central axes L1 and L2 of the two combustion air nozzles 33 and 34 and the central axis L3 of each fuel injection nozzle 41 do not intersect on the same plane.

[0036] Furthermore, in this embodiment, regenerative burners are installed by forming air vents 31 and 32 on opposing side walls 13a (right side in Figures 1 and 3) and 13b (left side in Figures 1 and 3) of the side walls 13 that constitute the furnace body 10, respectively. However, as shown in Figure 7, it is also possible to apply a type in which air vents 31 and 32 are formed on one side wall 13a of the side wall 13, spaced apart to the left and right, and combustion air nozzles 33 and 34 are provided at these air vents 31 and 32 to supply combustion air into the furnace body 10, and regenerative burners are further arranged adjacent to them to draw exhaust gas from inside the furnace body 10 through the air vents 31 and 32.

[0037] In this type as well, heat exchange chambers 35 and 36 are located outside the furnace body 10, each communicating with air inlets 31 and 32, and having heat storage bodies that recover heat from exhaust gases and preheat the combustion air supplied to the furnace body 10. Furthermore, the ceiling wall 12 is equipped with three fuel injection nozzles 41 (41a, 41b, 41c) for supplying ammonia into the furnace body 10. The central axes L1, L2 of the combustion air nozzles 33, 34 and the central axis L3 of the fuel injection nozzles 41 are arranged so as not to intersect on the same plane, and the combustion air supplied from the combustion air nozzles 33, 34 and the ammonia supplied from the fuel injection nozzles 41 are arranged so as not to come into direct contact.

[0038] Here, the central axis L3 of three equally spaced, vertically extending fuel injection nozzles 41 (41a, 41b, 41c) is positioned at the center of the central axes L1, L2 of the parallel, horizontally extending combustion air nozzles 33, 34, thereby enabling the creation of a symmetrical and well-balanced metal heating furnace with a regenerative burner. However, the arrangement of the three fuel injection nozzles 41 (41a, 41b, 41c) is not limited to the central axes L1, L2 of the combustion air nozzles 33, 34 and the central axis L3 of the fuel injection nozzles 41, as long as they do not intersect on the same plane.

[0039] Furthermore, in a metal heating furnace with a regenerative burner using ammonia as fuel, a configuration in which the central axes L1 and L2 of the combustion air nozzles 33 and 34 and the central axis L3 of each fuel injection nozzle 41 are arranged so as not to intersect on the same plane is not described in any of the aforementioned patent documents. [Explanation of Symbols]

[0040] 10 Furnace body 11 Hearth 12 Ceiling and Wall 13(13a,13b,13c,13d) Side wall 20 Ammonia supply unit 31 Air vent 32 Air vents 33 Combustion air nozzle 34 Combustion air nozzle 35 Heat exchange room 36 Heat exchange room 41(41a,41b,41c,41d,41e) Fuel injection nozzle 42 valves 47 Combustion Blower 47a Diverter Valve 47b Diverter Valve 48 Exhaust fan 48a Diverter Valve 48b Diverter Valve 50 Furnace body 51 Hearth 52 Ceiling and Wall 53 Side wall 61 Air vent 62 Air vents 63 Combustion Nozzle 64 Combustion Nozzles 65 Heat exchange room 66 Heat exchange room 67 Combustion Blower 67a Diverter Valve 67b Diverter Valve 68 Exhaust fan 68a Diverter Valve 68b Diverter Valve 70 burners 71 Mixed gas flow path 72 Ammonia supply means 73 Control means 74 Insertion section 75 Means of distribution 76 Distribution transport paths 77 Ammonia flow path L1 Combustion air nozzle center axis L2 Combustion air nozzle center axis L3 Fuel Injection Nozzle Center Axis

Claims

1. A metal heating furnace having a hearth, ceiling walls and side walls, and using ammonia as fuel, On each of the side walls, opposite side walls are formed and provided with combustion air nozzles for supplying combustion air into the furnace body, and an air port for drawing in exhaust gas from the furnace body, A heat exchange chamber is located outside the furnace body, communicates with each of the air vents, and has a heat storage body that recovers heat from the exhaust gas and preheats the combustion air supplied to the furnace body. The regenerative burner, which is provided on the ceiling wall and includes a fuel injection nozzle for supplying ammonia into the furnace body, repeatedly injects flames and sucks in exhaust gas at regular intervals, A metal heating furnace with a regenerative burner, characterized in that the combustion air nozzle and the fuel injection nozzle are arranged so that their central axes do not intersect on the same plane, and the combustion air supplied from the combustion air nozzle and the ammonia supplied from the fuel injection nozzle do not come into direct contact.

2. The metal heating furnace with a regenerative burner according to claim 1, characterized in that the central axes of the combustion air nozzles provided in air vents formed in opposite side walls of the aforementioned side wall coincide and form a straight line.

3. A metal heating furnace having a hearth, ceiling walls and side walls, and using ammonia as fuel, One of the side walls is provided with a combustion air nozzle that supplies combustion air into the furnace body, and an air port that draws in exhaust gas from the furnace body, A heat exchange chamber is located outside the furnace body, communicates with each of the air vents, and has a heat storage body that recovers heat from the exhaust gas and preheats the combustion air supplied to the furnace body. The regenerative burner, which is provided on the ceiling wall and includes a fuel injection nozzle for supplying ammonia into the furnace body, repeatedly injects flames and sucks in exhaust gas at regular intervals, A metal heating furnace with a regenerative burner, characterized in that the combustion air nozzle and the fuel injection nozzle are arranged so that their central axes do not intersect on the same plane, and the combustion air supplied from the combustion air nozzle and the ammonia supplied from the fuel injection nozzle do not come into direct contact.

4. The metal heating furnace with a regenerative burner according to claim 1 or 3, characterized in that only one fuel injection nozzle is provided.

5. The metal heating furnace with a regenerative burner according to claim 1 or 3, characterized in that a plurality of fuel injection nozzles are provided.

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