Radiant tube burner system and heating device

Abstract

To provide a radiant tube burner system and heating device that can reduce the cost required for reforming ammonia fuel. [Solution] The first radiant tube burner 1 includes a first burner 11, a first radiant tube 12, and a first connecting pipe 13. Combustion exhaust gas from the first burner 11 flows through the first radiant tube 12. The first connecting pipe 13 is connected to the first radiant tube 12. The second radiant tube burner 2 includes a second burner 21 and a first reformer 5. The first reformer 5 thermally decomposes ammonia fuel and guides the thermally decomposed ammonia fuel to the second burner 21. The first connecting pipe 13 is connected to the first reformer 5 and guides the combustion exhaust gas from the first burner 11 to the first reformer 5.

Description

Technical Field

[0001] The present disclosure relates to a radiant tube burner system and a heating device.

Background Art

[0002] In burners that mix and combust fuel and combustion air, fossil fuels are usually used as fuel. However, when fossil fuels are burned, relatively large amounts of greenhouse gases such as carbon dioxide are generated. Therefore, in recent years, in order to reduce greenhouse gases such as carbon dioxide, the use of fuels other than fossil fuels has been considered.

[0003] Ammonia fuel is a fuel other than fossil fuels. However, ammonia fuel is more difficult to burn compared to fossil fuels. The ammonia fuel combustion device described in Japanese Unexamined Patent Application Publication No. 2022-015464 (Patent Document 1) has a reformer that thermally decomposes ammonia fuel into hydrogen gas and nitrogen gas. The reformer has a catalyst and a heater that heats the catalyst.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] When using the reformer described in Patent Document 1 in a radiant tube burner system having a plurality of radiant tube burners, heaters equal in number to the number of radiant tube burners are provided. Therefore, as the number of radiant tube burners increases, the cost required for reforming ammonia fuel increases.

[0006] This disclosure has been made in view of the above-mentioned problems, and its purpose is to provide a radiant tube burner system and heating device that can reduce the cost required for reforming ammonia fuel. [Means for solving the problem]

[0007] The radiant tube burner system according to this disclosure burns ammonia fuel. The radiant tube burner system comprises a first radiant tube burner and a second radiant tube burner. The first radiant tube burner includes a first burner, a first radiant tube, and a first connecting pipe. Combustion exhaust gas from the first burner flows through the first radiant tube. The first connecting pipe is connected to the first radiant tube. The second radiant tube burner includes a second burner and a first reformer. The first reformer pyrolysis the ammonia fuel and guides the pyrolysis ammonia fuel to the second burner. The first connecting pipe is connected to the first reformer and guides the combustion exhaust gas from the first burner to the first reformer. [Effects of the Invention]

[0008] This disclosure provides a radiant tube burner system and heating device that can reduce the costs required for reforming ammonia fuel. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic diagram showing the configuration of a radiant tube burner system according to the first embodiment. [Figure 2] This is a block diagram showing the configuration of a radiant tube burner system according to the first embodiment. [Figure 3] This is a schematic diagram showing the configuration of the heating device according to the first embodiment. [Figure 4] This is a flowchart illustrating the operation of the radiant tube burner system according to the first embodiment. [Figure 5]This is a schematic diagram showing the relationship between the temperature of the reformer and the combustion state of the radiant tube burner in a radiant tube burner system according to the first embodiment. [Figure 6] This is a schematic diagram illustrating the operation of the radiant tube burner system according to the first embodiment. [Figure 7] This is a schematic diagram showing the configuration of the heating device according to the second embodiment. [Figure 8] This is a flowchart illustrating the operation of the radiant tube burner system according to the second embodiment. [Figure 9] This is a schematic diagram showing the relationship between the temperature of the reformer and the combustion state of the radiant tube burner in a radiant tube burner system according to the second embodiment. [Figure 10] This is a schematic diagram showing the configuration of a radiant tube burner system according to the first modified example. [Figure 11] This is a schematic diagram showing the configuration of a radiant tube burner system according to the second modified example. [Figure 12] This is a schematic diagram showing the configuration of a radiant tube burner system according to the third modified example. [Modes for carrying out the invention]

[0010] Embodiments of this disclosure will be described below with reference to the drawings. In the following drawings, the same or corresponding parts will be given the same reference numerals, and their descriptions will not be repeated.

[0011] (First Embodiment) <Radiant Tube Burner System> First, the configuration of the radiant tube burner system 100 according to the first embodiment will be described. In the following, the radiant tube burner system will also be referred to as the RT burner system, and the radiant tube burner will also be referred to as the RT burner.

[0012] As shown in FIG. 1, the RT burner system 100 has a first RT burner 1, a first fuel valve 71, a first gas valve 74, and a first air valve 77. The RT burner system 100 burns ammonia fuel (NH3).

[0013] The first RT burner 1 has a first burner 11, a first radiant tube 12, a first connecting pipe 13, and an independent reformer 4. The first burner 11 burns, for example, ammonia fuel. The front end of the first burner 11 is disposed inside the first radiant tube 12.

[0014] Combustion exhaust gas of the first burner 11 flows through the first radiant tube 12. The first radiant tube 12 has a first end 16 and a second end 17. Combustion air is supplied to the first end 16. The second end 17 is opposite to the first end 16. The first radiant tube 12 guides the combustion exhaust gas of the first burner 往 11 to the second end 17.

[0015] The first connecting pipe 13 is connected to the first radiant tube 12. Specifically, the first connecting pipe 13 is connected to the second end 17. Combustion exhaust gas of the first burner 11 flows into the first connecting pipe 13 from the first radiant tube 12.

[0016] The independent reformer 4 is connected to the first burner 11. The independent reformer 4 thermally decomposes at least a part of the ammonia fuel. The independent reformer 4 guides the thermally decomposed ammonia fuel and the remaining part that has not been decomposed to the first burner 11. Specifically, the independent reformer 4 guides hydrogen and nitrogen generated by the thermal decomposition of the ammonia fuel and the remaining part that has not been decomposed to the first burner 11. Hereinafter, the thermally decomposed ammonia fuel is also referred to as reformed ammonia fuel. The reformed ammonia fuel may include the remaining part of the ammonia fuel.

[0017] The independent reformer 4 includes, for example, a first pipe section 41, a first catalyst 42, an electric heater 43, and a first housing 44. Ammonia fuel is supplied to the inside of the first pipe section 41. The first catalyst 42 is housed in the first pipe section 41. The first catalyst 42 promotes the thermal decomposition of the ammonia fuel. The electric heater 43 heats the first pipe section 41 and the first catalyst 42. When the temperature of the first catalyst 42 is raised above a certain temperature, the first catalyst 42 is activated, and the thermal decomposition of the ammonia fuel is promoted. The first housing 44 houses the first pipe section 41, the first catalyst 42, and the electric heater 43.

[0018] The first fuel valve 71 opens and closes the supply path for ammonia fuel to the independent reformer 4. The first gas valve 74 opens and closes the supply path for the preceding gas to the independent reformer 4. The preceding gas is, for example, nitrogen gas (N2). The first air valve 77 opens and closes the supply path for combustion air to the first radiant tube 12.

[0019] The RT burner system 100 includes a second RT burner 2, a second fuel valve 72, a second gas valve 75, and a second air valve 78. The configuration of the second RT burner 2 may be substantially the same as that of the first RT burner 1. Specifically, the second RT burner 2 includes a second burner 21, a second radiant tube 22, a second connecting pipe 23, and a first reformer 5.

[0020] The second burner 21 burns ammonia fuel. The front end of the second burner 21 is located inside the second radiant tube 22. Combustion exhaust gas from the second burner 21 flows through the second radiant tube 22. The second radiant tube 22 has a third end 26 and a fourth end 27. Combustion air is supplied to the third end 26. The fourth end 27 is opposite the third end 26. The second radiant tube 22 guides the combustion exhaust gas from the second burner 21 to the fourth end 27.

[0021] The second connecting pipe 23 is connected to the second radiant tube 22. Specifically, the second connecting pipe 23 is connected to the fourth end 27. Combustion exhaust gas from the second burner 21 flows into the second connecting pipe 23 from the second radiant tube 22.

[0022] The first reformer 5 is connected to the second burner 21. The first reformer 5 pyrolyzes at least a portion of the ammonia fuel. The first reformer 5 guides the reformed ammonia fuel to the second burner 21. The first reformer 5 has a second pipe section 51, a second catalyst 52, and a second housing 54.

[0023] Ammonia fuel is supplied inside the second pipe section 51. The second catalyst 52 is housed in the second pipe section 51. The configuration of the second catalyst 52 is the same as that of the first catalyst 42. The second housing 54 houses the second pipe section 51 and the second catalyst 52. The shape of the second housing 54 is, for example, tubular. The second housing 54 and the second pipe section 51 form a double-pipe structure.

[0024] The first reformer 5 is connected to the first connecting pipe 13. From another perspective, the first connecting pipe 13 connects the first radiant tube 12 to the first reformer 5. Specifically, the first connecting pipe 13 connects the inside of the first radiant tube 12 to the inside of the second housing 54. The first connecting pipe 13 guides the combustion exhaust gas from the first burner 11 to the first reformer 5. The second housing 54 has a first exhaust port 59. The first exhaust port 59 discharges the combustion exhaust gas supplied from the first connecting pipe 13.

[0025] The second fuel valve 72 opens and closes the supply path for ammonia fuel to the first reformer 5. The second gas valve 75 opens and closes the supply path for preceding gas to the first reformer 5. The second air valve 78 opens and closes the supply path for combustion air to the second radiant tube 22.

[0026] The RT burner system 100 includes a third RT burner 3, a third fuel valve 73, a third gas valve 76, and a third air valve 79. The configuration of the third RT burner 3 may be substantially the same as that of the second RT burner 2. Specifically, the third RT burner 3 includes a third burner 31, a third radiant tube 32, a third connecting pipe 33, and a second reformer 6. The third burner 31, third radiant tube 32, third connecting pipe 33, and second reformer 6 correspond to the second burner 21, second radiant tube 22, second connecting pipe 23, and first reformer 5, respectively. The third radiant tube 32 also has a fifth end 36 and a sixth end 37. The fifth end 36 and sixth end 37 correspond to the third end 26 and fourth end 27, respectively.

[0027] The second reformer 6 is connected to the third burner 31. The second reformer 6 pyrolyzes at least a portion of the ammonia fuel. The second reformer 6 guides the reformed ammonia fuel to the third burner 31. The second reformer 6 has a third pipe section 61, a third catalyst 62, and a third housing 64. The third pipe section 61, the third catalyst 62, and the third housing 64 correspond to the second pipe section 51, the second catalyst 52, and the second housing 54, respectively.

[0028] The second reformer 6 is connected to the second connecting pipe 23. From another perspective, the second connecting pipe 23 connects the second radiant tube 22 to the second reformer 6. Specifically, the second connecting pipe 23 connects the inside of the second radiant tube 22 to the inside of the third housing 64. The second connecting pipe 23 guides the combustion exhaust gas from the second burner 21 to the second reformer 6.

[0029] The third housing 64 has a second exhaust port 69. The second exhaust port 69 discharges the combustion exhaust gas supplied from the second connecting pipe 23.

[0030] The third fuel valve 73 opens and closes the supply path for ammonia fuel to the second reformer 6. The third gas valve 76 opens and closes the supply path for preceding gas to the second reformer 6. The third air valve 79 opens and closes the supply path for combustion air to the third radiant tube 32.

[0031] The RT burner system 100 includes a first thermometer 81, a second thermometer 82, and a third thermometer 83. The first thermometer 81 measures the temperature of the independent reformer 4. Specifically, the first thermometer 81 measures, for example, the temperature of the first catalyst 42. Similarly, the second thermometer 82 measures the temperature of the first reformer 5. The third thermometer 83 measures the temperature of the second reformer 6.

[0032] The RT burner system 100 may have a fourth RT burner (not shown). The configuration of the fourth RT burner may be substantially the same as that of the second RT burner 2. The third connecting pipe 33 may be connected to a reformer (not shown) of the fourth RT burner.

[0033] As shown in Figure 2, the RT burner system 100 has a control unit 9. The control unit 9 controls the opening and closing of the first fuel valve 71, the second fuel valve 72, and the third fuel valve 73, respectively. In other words, the control unit 9 controls the start and stop of the supply of ammonia fuel to each of the independent reformers 4, the first reformer 5, and the second reformer 6. The control unit 9 can adjust the flow rate of ammonia fuel supplied to each of the independent reformers 4, the first reformer 5, and the second reformer 6 by controlling each of the first fuel valve 71, the second fuel valve 72, and the third fuel valve 73.

[0034] The control unit 9 controls the opening and closing of the first gas valve 74, the second gas valve 75, and the third gas valve 76, respectively. From another perspective, the control unit 9 controls the start and stop of the supply of lead gas to the independent reformer 4, the first reformer 5, and the second reformer 6, respectively. By controlling the first gas valve 74, the second gas valve 75, and the third gas valve 76, the control unit 9 can adjust the flow rate of lead gas supplied to the independent reformer 4, the first reformer 5, and the second reformer 6, respectively.

[0035] The control unit 9 controls the opening and closing of the first air valve 77, the second air valve 78, and the third air valve 79, respectively. From another perspective, the control unit 9 controls the start and stop of the supply of combustion air to the first radiant tube 12, the second radiant tube 22, and the third radiant tube 32, respectively. By controlling the first air valve 77, the second air valve 78, and the third air valve 79, the control unit 9 can adjust the flow rate of combustion air supplied to the first radiant tube 12, the second radiant tube 22, and the third radiant tube 32, respectively.

[0036] The control unit 9 controls the electric heater 43. Specifically, the control unit 9 heats the first pipe section 41 and the first catalyst 42 by outputting a signal to the electric heater 43.

[0037] The first thermometer 81 outputs a signal regarding the temperature of the independent reformer 4 to the control unit 9. The second thermometer 82 outputs a signal regarding the temperature of the first reformer 5 to the control unit 9. The third thermometer 83 outputs a signal regarding the temperature of the second reformer 6 to the control unit 9.

[0038] <Heating device> Next, the configuration of the heating device 200 according to the first embodiment will be described. As shown in Figure 3, the heating device 200 has the RT burner system 100 described above and a furnace wall 8. The heating device 200 is a continuous annealing furnace (CAL) or a continuous galvanizing apparatus (CGL), etc.

[0039] The furnace wall 8 forms an internal space 89. From another perspective, the furnace wall 8 separates the internal space 89 from the external space 88. An object to be heated (not shown) is placed in the internal space 89. The RT burner system 100 heats the object to be heated.

[0040] The first RT burner 1 is attached to the furnace wall 8. Specifically, the first radiant tube 12 is attached to the furnace wall 8. A part of the first radiant tube 12 protrudes from the furnace wall 8 into the internal space 89. Each of the first end 16 and the second end 17 is arranged in the external space 88. The first connecting pipe 13 is arranged in the external space 88. The independent reformer 4 is arranged in the external space 88.

[0041] Similarly, the second RT burner 2 is attached to the furnace wall 8. The first reformer 5 is arranged in the external space 88. The third RT burner 3 is attached to the furnace wall 8. The second reformer 6 is arranged in the external space 88.

[0042] <Operation of the RT burner system and the heating device> Next, the operation of the RT burner system 100 and the heating device 200 will be described. As shown in FIG. 4, first, the control unit 9 starts heating the independent reformer 4 (step S10). Specifically, the control unit 9 heats the independent reformer 4 by controlling, for example, the electric heater 43. As a result, as shown in FIG. 5, the temperature of the independent reformer 4 rises.

[0043] In step S10, the control unit 9 starts supplying the pilot gas to the independent reformer 4 by controlling the first gas valve 74. The pilot gas supplied to the independent reformer 4 flows into the first reformer 5 through the first RT burner 1 and is discharged from the first exhaust port 59.

[0044] Next, the control unit 9 determines whether or not the temperature of the independent reformer 4 has reached the target temperature T1 based on the signal regarding the temperature of the independent reformer 4 output from the first thermometer 81 (step S20). The target temperature T1 is set based on the preferable temperature range of the first catalyst 42 in the decomposition of the ammonia fuel. The preferable temperature range of the first catalyst 42 in the decomposition of the ammonia fuel is, for example, about 300°C or higher and 400°C or lower.

[0045] If the temperature of the independent reformer 4 is below the target temperature T1 (NO in step S20), the control unit 9 continues the process in step S20. If the temperature of the independent reformer 4 reaches the target temperature T1 (YES in step S20), the control unit 9 starts combustion of the first RT burner 1 (step S30).

[0046] In step S30, the control unit 9 first starts supplying combustion air to the first radiant tube 12 by controlling the first air valve 77. Subsequently, the control unit 9 starts supplying ammonia fuel to the independent reformer 4. Specifically, the control unit 9 switches the gas supplied to the independent reformer 4 from the preceding gas to ammonia fuel by controlling the first gas valve 74 and the first fuel valve 71, respectively. The ammonia fuel supplied to the independent reformer 4 is heated together with the first catalyst 42 by the electric heater 43. As a result, at least a portion of the ammonia fuel is thermally decomposed and supplied to the first burner 11 as reformed ammonia fuel.

[0047] If the independent reformer 4 is heated without supplying fluid to it, the gas lingering in the first catalyst 42 will also be heated, causing the entire first catalyst 42 to overheat. If ammonia fuel is then supplied to the independent reformer 4 under these conditions, the ammonia fuel will initially flow at room temperature, causing the temperature of the first catalyst 42 to drop rapidly. In this case, the thermal decomposition of the ammonia fuel flowing inside the independent reformer 4 will be insufficient for a while after the ammonia fuel supply begins.

[0048] In short, because the temperature of the ammonia fuel entering the first catalyst 42 is low, during operation the temperature upstream of the fuel flow in the first catalyst 42 is lower than the temperature downstream, creating a temperature gradient in the first catalyst 42. Therefore, as described above, a temperature gradient is created in advance in the first catalyst 42 by heating the independent reformer 4 while supplying the preceding gas. This prevents a rapid drop in the temperature of the first catalyst 42 when the ammonia fuel is started to flow. As a result, the ammonia fuel can be sufficiently thermally decomposed even immediately after the start of ammonia fuel supply. In addition, the heated preceding gas flows through the first RT burner 1, preheating the inside of the first RT burner 1.

[0049] In step S30, the control unit 9 then energizes a spark plug (not shown) located near the fuel injection port A1 of the first burner 11, generating a spark to ignite the first burner 11 and burn the reformed ammonia fuel. As a result, a first flame F1 is generated inside the first radiant tube 12, as shown in Figure 6.

[0050] The combustion exhaust gas from the first burner 11 is supplied to the first reformer 5 through the first radiant tube 12 and the first connecting pipe 13. The combustion exhaust gas from the first burner 11 heats the second pipe section 51 and the second catalyst 52. As a result, the temperature of the first reformer 5 rises, as shown in Figure 5. The combustion exhaust gas from the first burner 11 is the combustion exhaust gas generated from the first flame F1.

[0051] In process S30, the control unit 9 starts supplying the lead gas to the first reformer 5 by controlling the second gas valve 75. The lead gas supplied to the first reformer 5 flows into the second reformer 6 through the second burner 21, the second radiant tube 22, and the second connecting pipe 23, and is discharged from the second exhaust port 69.

[0052] Next, the control unit 9 determines whether the temperature of the first reformer 5 has reached the target temperature T2 based on the temperature signal of the first reformer 5 output from the second thermometer 82 (step S40). The target temperature T2 may be the same as the target temperature T1.

[0053] If the temperature of the first reformer 5 is below the target temperature T2 (NO in step S40), the control unit 9 continues the process in step S40. If the temperature of the first reformer 5 reaches the target temperature T2 (YES in step S40), the control unit 9 starts combustion of the second RT burner 2 (step S50).

[0054] In step S50, the control unit 9 first controls the second air valve 78 to start supplying combustion air to the second radiant tube 22. Subsequently, the control unit 9 controls the second gas valve 75 and the second fuel valve 72, respectively, to switch the gas supplied to the first reformer 5 from the preceding gas to ammonia fuel. The ammonia fuel and second catalyst 52 supplied to the first reformer 5 are heated by the combustion exhaust gas from the first burner 11 and the heat transfer from the first reformer 5. As a result, at least a portion of the ammonia fuel is thermally decomposed and supplied to the second burner 21 as reformed ammonia fuel.

[0055] In step S50, the control unit 9 then energizes a spark plug (not shown) located near the fuel injection port A2 of the second burner 21, generating a spark to ignite the second burner 21 and burn the reformed ammonia fuel. As a result, a second flame F2 is generated inside the second radiant tube 22, as shown in Figure 6.

[0056] The combustion exhaust gas from the second burner 21 is supplied to the second reformer 6 through the second radiant tube 22 and the second connecting pipe 23. The combustion exhaust gas from the second burner 21 heats the third pipe section 61 and the third catalyst 62. As a result, the temperature of the second reformer 6 rises, as shown in Figure 5. The combustion exhaust gas from the second burner 21 is the combustion exhaust gas generated by the second flame F2.

[0057] In step S50, the control unit 9 starts supplying the lead gas to the second reformer 6 by controlling the third gas valve 76. The lead gas supplied to the second reformer 6 flows through the third burner 31 and the third radiant tube 32.

[0058] Next, the control unit 9 determines whether the temperature of the second reformer 6 has reached the target temperature T3 based on the temperature signal of the second reformer 6 output from the third thermometer 83 (step S60). The target temperature T3 may be the same as the target temperatures T1 and T2, respectively.

[0059] If the temperature of the second reformer 6 is below the target temperature T3 (NO in step S60), the control unit 9 continues the process in step S60. If the temperature of the second reformer 6 reaches the target temperature T3 (YES in step S60), the control unit 9 starts combustion of the third RT burner 3 (step S70).

[0060] In step S70, the control unit 9 performs the same processing as in step S50. Specifically, the control unit 9 controls the third fuel valve 73, the third gas valve 76, and the third air valve 79, respectively, in the same way as the control of the second fuel valve 72, the second gas valve 75, and the second air valve 78 in step S50. Then, it energizes the spark plug (not shown) located near the fuel injection port A3 of the third burner 31, generating a spark to ignite the third burner 31 and burn the reformed ammonia fuel. As shown in Figure 6, the third flame F3 is generated inside the third radiant tube 32. Using the first flame F1, the second flame F2, and the third flame F3, the RT burner system 100 heats the object to be heated.

[0061] Next, the effects and benefits of the RT burner system 100 according to the first embodiment will be described. Ammonia fuel is difficult to burn. Therefore, when using ammonia fuel in an RT burner system with multiple RT burners, it is necessary to reform the ammonia fuel by thermally decomposing the ammonia fuel supplied to each of the RT burners. Consequently, as the number of RT burners increases, the required ammonia fuel decomposition capacity increases, and the running costs and equipment costs of the heaters that heat the ammonia fuel increase. Therefore, the cost required to reform the ammonia fuel increases.

[0062] To solve this problem, according to the RT burner system 100 of the first embodiment, the first RT burner 1 has a first burner 11 and a first connecting pipe 13. The second RT burner 2 has a first reformer 5. The first connecting pipe 13 guides the combustion exhaust gas from the first burner 11 to the first reformer 5. Therefore, the first reformer 5 can be heated using the high-temperature combustion exhaust gas generated by the flame F1 of the first burner 11. This reduces the running costs required to reform the ammonia fuel used by the second RT burner 2. As a result, the cost required to reform the ammonia fuel can be reduced for the entire RT burner system 100.

[0063] According to the RT burner system 100 of the first embodiment, a heat source for heating the first reformer 5 is not required. Therefore, the equipment cost required to heat the first reformer 5 can be reduced.

[0064] According to the RT burner system 100 of the first embodiment, the second RT burner 2 has a second burner 21 and a second connecting pipe 23. The third RT burner 3 has a second reformer 6. The second connecting pipe 23 guides the combustion exhaust gas from the second burner 21 to the second reformer 6. Therefore, the high-temperature combustion exhaust gas generated by the flame F2 of the second burner 21 can be used to heat the second reformer 6. This reduces the running costs required to reform the ammonia fuel used by the third RT burner 3. As a result, the cost required to reform the ammonia fuel can be effectively reduced throughout the entire RT burner system 100.

[0065] According to the RT burner system 100 of the first embodiment, the first RT burner 1 has an independent reformer 4. The independent reformer 4 has an electric heater 43 that heats the ammonia fuel and the first catalyst 42. Therefore, the first RT burner 1 can reliably reform the ammonia fuel for use. As a result, the RT burner system 100 can heat the object to be heated using only ammonia fuel (dedicated combustion).

[0066] The heating device 200, such as a heat treatment furnace according to the first embodiment, has the RT burner system 100 according to the first embodiment. Therefore, the cost required for reforming ammonia fuel can be reduced.

[0067] (Second Embodiment) Next, the configuration of the RT burner system 100 and heating device 200 according to the second embodiment will be described. The RT burner system 100 according to the second embodiment differs from the RT burner system 100 according to the first embodiment mainly in that the first connecting pipe 13 is connected to the first reformer 5 and the second reformer 6, respectively, and is substantially the same as the RT burner system 100 according to the first embodiment in other respects. The following description will focus on the differences from the RT burner system 100 according to the first embodiment.

[0068] As shown in Figure 7, in the RT burner system 100 used in the heating device 200 according to the second embodiment, the first connecting pipe 13 is connected to the first reformer 5 and the second reformer 6, respectively. The first connecting pipe 13 guides the combustion exhaust gas from the first burner 11 to the first reformer 5 and the second reformer 6, respectively. The first connecting pipe 13 is branched between the end connected to the first RT burner 1 and the end connected to the first reformer 5.

[0069] The second RT burner 2 may be spaced apart from the second reformer 6. The second RT burner 2 may not have a second connecting pipe 23 (see Figure 1). The combustion exhaust gas from the second burner 21 may be discharged to the external space 88 from the fourth end 27.

[0070] Although not shown in the diagram, the fourth end 27 of the second radiant tube 22 may be connected to the first connecting pipe 13. The first connecting pipe 13 may guide both the combustion exhaust gas from the first burner 11 and the combustion exhaust gas from the second burner 21 to the second reformer 6. The first connecting pipe 13 may be connected to the reformer of the fourth RT burner (not shown). The first connecting pipe 13 may guide the combustion exhaust gas from the first burner 11 to the reformer of the fourth RT burner.

[0071] Next, the operation of the RT burner system 100 and heating device 200 according to the second embodiment will be described.

[0072] As shown in Figure 8, after process S30, the control unit 9 performs processes S40 and S60 in parallel. Specifically, as shown in Figure 7, in process S30, the high-temperature combustion exhaust gas from the first burner 11 is supplied to the first reformer 5 and the second reformer 6, respectively. This heats up the first reformer 5 and the second reformer 6. Consequently, as shown in Figure 9, the temperature of the first reformer 5 and the second reformer 6 rises.

[0073] The control unit 9 starts combustion of the second RT burner 2 when the temperature of the first reformer 5 reaches the target temperature T2, and starts combustion of the third RT burner 3 when the temperature of the second reformer 6 reaches the target temperature T3. In Figure 9, the combustion start of the second RT burner 2 and the combustion start of the third RT burner 3 are shown to be simultaneous. However, the combustion start of the second RT burner 2 and the combustion start of the third RT burner 3 do not have to be simultaneous.

[0074] According to the RT burner system 100 of the second embodiment, the first connecting pipe 13 guides the combustion exhaust gas from the first burner 11 to the first reformer 5 and the second reformer 6, respectively. Therefore, the combustion exhaust gas from the first burner 11 can be used to heat the first reformer 5 and the second reformer 6 simultaneously. In the first embodiment, it was necessary to ignite the first burner 11 and the second burner 21 in sequence, so if there were many burners, it took time for all the burners to ignite and for the furnace temperature to reach the set value. However, with this configuration, the reformers of all the burners can be heated simultaneously, and all the burners can be ignited at almost the same time, thus shortening the time it takes to raise the furnace temperature to the set value (equipment start-up time).

[0075] Next, we will describe RT burner systems 100 according to modifications of the first and second embodiments.

[0076] (First variation) The above description concerns a configuration in which an electric heater 43 is used as a heating means for the independent reformer 4. However, the configuration of the independent reformer 4 is not limited to the above configuration. As shown in Figure 10, the independent reformer 4 may also have a heating burner 85, a fourth fuel valve 86, and a fourth air valve 87. The heating burner 85 burns fossil fuels. Fossil fuels include, for example, liquefied natural gas (LNG). Fossil fuels may also include liquefied petroleum gas (LPG), coke oven gas, blast furnace gas, converter gas, etc.

[0077] The fourth fuel valve 86 opens and closes the supply path for fossil fuel to the heating burner 85. The fourth air valve 87 opens and closes the supply path for combustion air to the heating burner 85. The control unit 9 controls the fourth fuel valve 86 and the fourth air valve 87, respectively.

[0078] According to the first modified RT burner system 100, the independent reformer 4 can be heated without using an electric heater 43. This reduces the power consumption of the RT burner system 100.

[0079] (Second variation) As shown in Figure 11, the first RT burner 1 does not necessarily have an independent reformer 4. The first burner 11 may burn fossil fuels. The first fuel valve 71 may open or close the supply path for fossil fuels to the first burner 11.

[0080] According to the RT burner system 100 of the second modification, equipment costs can be reduced compared to the case where the first RT burner 1 has an independent reformer 4. In addition, the size of the RT burner system 100 can be reduced compared to the case where the first RT burner 1 has an independent reformer 4.

[0081] According to the RT burner system 100 of the second modification, the configuration of the first RT burner 1 may be the same as that of a conventional radiant tube burner, except that it has a first connecting pipe 13. Therefore, the heating device 200 according to this disclosure can be manufactured by using the radiant tube burner of an existing facility as the first RT burner 1 and modifying the existing facility to attach other parts.

[0082] (Third variation) The RT burner system 100 may have a cooling section for cooling the first reformer 5. Specifically, as shown in Figure 12, the RT burner system 100 may have an air supply passage 90 and a fifth air valve 91. The air supply passage 90 is connected, for example, to the first connecting pipe 13. The air supply passage 90 supplies cooling air to the first reformer 5. The fifth air valve 91 opens and closes the air supply passage 90. The control unit 9 controls the fifth air valve 91.

[0083] When the first reformer 5 has a second catalyst 52, the reforming of the ammonia fuel may be inhibited due to excessive heating of the second catalyst 52. According to the RT burner system 100 of the third modified example, the first reformer 5 can be cooled using the air supply passage 90. Therefore, it becomes easier to control the temperature of the first reformer 5. This makes it easy to suppress the inhibition of ammonia fuel reforming.

[0084] The air supply passage 90 may also be connected to the first reformer 5. The RT burner system 100 may further have an air supply passage for supplying cooling air to the second reformer 6.

[0085] (Other variations) The above describes a configuration in which the first RT burner 1, the second RT burner 2, and the third RT burner 3 are arranged in that order. However, the arrangement of each of the first RT burner 1, the second RT burner 2, and the third RT burner 3 is not particularly limited. The first RT burner 1, the second RT burner 2, and the third RT burner 3 do not have to be arranged in a row. The third RT burner 3 may be placed between the first RT burner 1 and the second RT burner 2. Other RT burners (not shown) may be placed between the first RT burner 1 and the second RT burner 2. Other RT burners are RT burners that are not connected to each of the first RT burner 1, the second RT burner 2, and the third RT burner 3. Other RT burners may burn ammonia fuel or fossil fuels.

[0086] The number of RT burners is not particularly limited. In the above, only one set of RT burners was illustrated, in which the first RT burner to start combustion (first RT burner 1) and the subsequent RT burners to start combustion (second RT burner 2, third RT burner 3) are connected to each other. However, the RT burner system 100 may have more RT burners connected to form sets, or it may have multiple such sets of RT burners.

[0087] In the above example, the radiant tube was U-shaped, but the shape of the radiant tube is not particularly limited. The radiant tube may be W-shaped or I-shaped (single-ended).

[0088] Furthermore, although the thermal decomposition of ammonia fuel was accelerated here by heating and activating the catalyst, ammonia fuel also decomposes thermally when heated, so the independent reformer 4, the first reformer 5, and the second reformer 6 do not necessarily need to contain a catalyst. In other words, the first pipe section 41, the second pipe section 51, and the third pipe section 61 do not necessarily need to contain a catalyst. In this case, the temperatures of the independent reformer 4, the first reformer 5, and the second reformer 6 are, for example, the temperatures of the first pipe section 41, the second pipe section 51, and the third pipe section 61, respectively.

[0089] If the independent reformer 4, the first reformer 5, and the second reformer 6 do not each have a catalyst, the temperature of each of the independent reformer 4, the first reformer 5, and the second reformer 6 during ammonia fuel decomposition is preferably between 300°C and 700°C. The target temperatures T1, T2, and T3 are determined based on this temperature range. If the independent reformer 4, the first reformer 5, and the second reformer 6 each have a catalyst, the efficiency of thermal decomposition increases, allowing for a reduction in the size of the RT burner system 100.

[0090] The outer surfaces of the first pipe section 41, the second pipe section 51, and the third pipe section 61 may each be provided with fins or other irregularities. This increases the surface area of ​​each of the first pipe section 41, the second pipe section 51, and the third pipe section 61. This allows for efficient heating of the ammonia fuel and catalyst.

[0091] The various aspects of this disclosure are summarized below as an appendix. (Note 1) A radiant tube burner system for burning ammonia fuel, It comprises a first radiant tube burner and a second radiant tube burner, The first radiant tube burner is, First burner and, A first radiant tube through which the combustion exhaust gas from the first burner flows, Includes a first connecting pipe connected to the first radiant tube, The second radiant tube burner is, The second burner, The system includes a first reformer that thermally decomposes the ammonia fuel and guides the thermally decomposed ammonia fuel to the second burner, A radiant tube burner system in which the first connecting pipe is connected to the first reformer and guides the combustion exhaust gas of the first burner to the first reformer. (Note 2) Equipped with a third radiant tube burner, The third radiant tube burner is, The third burner, The system includes a second reformer that thermally decomposes the ammonia fuel and guides the thermally decomposed ammonia fuel to the third burner, The second radiant tube burner is, A second radiant tube through which the combustion exhaust gas from the second burner flows, Includes a second connecting pipe connected to the second radiant tube, The radiant tube burner system as described in Appendix 1, wherein the second connecting pipe is connected to the second reformer and guides the combustion exhaust gas of the second burner to the second reformer. (Note 3) Equipped with a third radiant tube burner, The third radiant tube burner is, The third burner, The system includes a second reformer that thermally decomposes the ammonia fuel and guides the thermally decomposed ammonia fuel to the third burner, The radiant tube burner system as described in Appendix 1, wherein the first connecting pipe is connected to the second reformer and guides the combustion exhaust gas of the first burner to the second reformer. (Note 4) The first radiant tube burner includes an independent reformer that thermally decomposes the ammonia fuel and guides the thermally decomposed ammonia fuel to the first burner. The radiant tube burner system according to any one of the appendices 1 to 3, wherein the independent reformer has an electric heater for heating the ammonia fuel. (Note 5) The first radiant tube burner includes an independent reformer that thermally decomposes the ammonia fuel and guides the thermally decomposed ammonia fuel to the first burner. The independent reformer has a heating burner for heating the ammonia fuel, The heating burner is a radiant tube burner system according to any one of the appendices 1 to 3, for burning fossil fuels. (Note 6) The first burner is a radiant tube burner system according to any one of the appendices 1 to 3, for burning fossil fuels. (Note 7) A thermometer for measuring the temperature of the first reformer, A radiant tube burner system according to any one of Appendix 1 to 6, comprising: a control unit that initiates combustion in the second burner based on a temperature signal of the first reformer output from the thermometer. (Note 8) A radiant tube burner system as described in any one of the items from Appendix 1 to Appendix 7, A heating device comprising a furnace wall to which the first radiant tube burner and the second radiant tube burner are each attached.

[0092] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims rather than by the embodiments described above, and all modifications within the meaning and scope of the claims are intended to be included. [Explanation of Symbols]

[0093] 1. First Radiant Tube Burner (First RT Burner) 2. Second Radiant Tube Burner (Second RT Burner) 3. Third Radiant Tube Burner (Third RT Burner) 4 Independent reformers 5. First reformer 6. Second reformer 8 Furnace wall 9. Control Unit 11. First Burner 12. First Radiant Tube 13. First connecting pipe 16 First end 17 Second end 21. Second Burner 22. Second Radiant Tube 23. Second connecting pipe 26 Third end 27 4th end 31. Third Burner 32 Third Radiant Tube 33 Third connecting pipe 36 5th end 37 6th end 41. First Section 42 First Catalyst 43 Electric heater 44. First cabinet 51 Second Section 52 Second Catalyst 54 Second cabinet 59 First exhaust port 61 Third Section 62 Third Catalyst 64 Third cabinet 69 Second exhaust port 71. First fuel valve 72. Second fuel valve 73 Third fuel valve 74. First gas valve 75. Second gas valve 76 Third gas valve 77. First air valve 78. Second air valve 79 Third air valve 81 1st thermometer 82 Second thermometer 83 Third thermometer 85 Heating burner 86. Fourth fuel valve 87. Fourth air valve 88 External space 89 Interior space 90 Air supply path 91 Fifth air valve 100 Radiant Tube Burner System (RT Burner System) 200 Heating device A1 fuel injection port A2 fuel injection port A3 fuel injection port F1 First Flame F2 Second Flame F3 3rd flame

Claims

1. A radiant tube burner system for burning ammonia fuel, It comprises a first radiant tube burner and a second radiant tube burner, The first radiant tube burner is, First burner and, A first radiant tube through which the combustion exhaust gas from the first burner flows, Includes a first connecting pipe connected to the first radiant tube, The second radiant tube burner is, The second burner, The first reformer includes a first reformer that thermally decomposes the ammonia fuel and guides the thermally decomposed ammonia fuel to the second burner, A radiant tube burner system in which the first connecting pipe is connected to the first reformer and guides the combustion exhaust gas of the first burner to the first reformer.

2. Equipped with a third radiant tube burner, The third radiant tube burner is, The third burner, The system includes a second reformer that thermally decomposes the ammonia fuel and guides the thermally decomposed ammonia fuel to the third burner, The second radiant tube burner is, The second radiant tube through which the combustion exhaust gas from the second burner flows, Includes a second connecting pipe connected to the second radiant tube, The radiant tube burner system according to claim 1, wherein the second connecting pipe is connected to the second reformer and guides the combustion exhaust gas of the second burner to the second reformer.

3. Equipped with a third radiant tube burner, The third radiant tube burner is, The third burner, The system includes a second reformer that thermally decomposes the ammonia fuel and guides the thermally decomposed ammonia fuel to the third burner, The radiant tube burner system according to claim 1, wherein the first connecting pipe is connected to the second reformer and guides the combustion exhaust gas of the first burner to the second reformer.

4. The first radiant tube burner includes an independent reformer that thermally decomposes the ammonia fuel and guides the thermally decomposed ammonia fuel to the first burner. The radiant tube burner system according to any one of claims 1 to 3, wherein the independent reformer has an electric heater for heating the ammonia fuel.

5. The first radiant tube burner includes an independent reformer that thermally decomposes the ammonia fuel and guides the thermally decomposed ammonia fuel to the first burner. The independent reformer has a heating burner for heating the ammonia fuel, The radiant tube burner system according to any one of claims 1 to 3, wherein the heating burner burns fossil fuels.

6. The radiant tube burner system according to any one of claims 1 to 3, wherein the first burner burns fossil fuels.

7. A thermometer for measuring the temperature of the first reformer, A radiant tube burner system according to any one of claims 1 to 3, comprising: a control unit that initiates combustion in the second burner based on a temperature signal of the first reformer output from the thermometer.

8. A radiant tube burner system according to any one of claims 1 to 3, A heating device comprising a furnace wall to which the first radiant tube burner and the second radiant tube burner are each attached.

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