Furnace

Abstract

A furnace 1 includes: a first burner group 10 including at least one first burner 11, the at least one first burner 11 injecting a first fuel F1 containing ammonia into a combustion space S and combusting the first fuel F1 at a first air ratio; and a second burner group 20 including at least one second burner 21, the at least one second burner 21 injecting a second fuel F2 containing a fossil fuel into the combustion space S and combusting the second fuel F2 at a second air ratio higher than the first air ratio.

Description

furnace

[0001] This application claims the benefit of priority from Japanese Patent Application No. 2023-188627, filed on November 2, 2023, the contents of which are incorporated herein by reference.

[0002] Ammonia may be used as a fuel in the furnace. For example, Patent Document 1 discloses a boiler that uses ammonia and a fossil fuel. The boiler includes a burner configured to burn the fossil fuel and a port for supplying the ammonia fuel.

[0003] Japanese Patent Application Laid-Open No. 2019-178823

[0004] Ammonia is CO ２ Ammonia is known as a fuel that does not emit NOx. However, when ammonia is burned, NOx is generated. Therefore, when ammonia is used in such a furnace, NOx can be a problem.

[0005] The present disclosure aims to provide a furnace that can reduce NOx when ammonia is used as fuel.

[0006] A furnace according to one aspect of the present disclosure comprises: a first burner group including at least one first burner, wherein the at least one first burner injects a first fuel including ammonia into a combustion space and burns the first fuel at a first air ratio; and a second burner group including at least one second burner, wherein the at least one second burner injects a second fuel including a fossil fuel into the combustion space and burns the second fuel at a second air ratio higher than the first air ratio.

[0007] The first air ratio may be greater than 0 and less than 1.0, and the second air ratio may be 1.0 or greater.

[0008] The first air ratio may be equal to or greater than 0.6 and less than 1.0, and the second air ratio may be equal to or greater than 1.1 and less than 1.3.

[0009] The furnace may include a control device that controls the second burner group, and the control device may adjust the second air ratio according to the ammonia co-firing ratio in the furnace.

[0010] The at least one second burner may be supplied with air such that the combustion temperature of the second fuel is below 1800K.

[0011] At least one second burner may be supplied with exhaust gas from the furnace.

[0012] The furnace may comprise a heat exchanger for heating air supplied to the at least one first burner with exhaust gases from the furnace.

[0013] The first burner group may include a plurality of first burners, and the second burner group may include a plurality of second burners, and the distance between adjacent first burners among the plurality of first burners may be shorter than the distance between adjacent second burners among the plurality of second burners.

[0014] According to the present disclosure, NOx can be reduced when ammonia is used as a fuel.

[0015] Fig. 1 is a schematic cross-sectional view of a boiler equipped with a furnace according to an embodiment. Fig. 2 is a schematic cross-sectional view taken along line II-II in Fig. 1. Fig. 3 is a schematic cross-sectional view of a naphtha cracking furnace equipped with a furnace according to another embodiment. Fig. 4 shows a diagram of an ammonia reaction pathway.

[0016] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Specific dimensions, materials, numerical values, etc. shown in the embodiments are merely examples for ease of understanding and do not limit the present disclosure unless otherwise specified. In this specification and drawings, elements having substantially the same functions and configurations are designated by the same reference numerals to avoid redundant explanation, and elements not directly related to the present disclosure are not shown.

[0017] 1 is a schematic cross-sectional view of a boiler 100 including a furnace 1 according to an embodiment. In this embodiment, the furnace 1 is applied to the boiler 100. In other embodiments, the furnace 1 may be applied to other equipment. For example, the boiler 100 includes the furnace 1 and a flue 2. The furnace 1 also includes a first burner group 10, a second burner group 20, an air port group 30, and a control device 90. The boiler 100 and the furnace 1 may further include other components.

[0018] The furnace 1 extends vertically. The furnace 1 defines a combustion space S. In this disclosure, the combustion space means a space in which fuel is combusted. An exhaust port D is provided at the bottom of the furnace 1. The exhaust port D discharges ash generated by combustion to the outside.

[0019] The furnace 1 combusts a first fuel F1 containing ammonia and a second fuel F2 containing a fossil fuel. For example, the furnace 1 may combust only the first fuel F1 or the second fuel F2 as needed. A flame FL is generated by the combustion. For example, the boiler 100 includes a superheater (not shown) installed on the upper part of the furnace 1. The superheater exchanges heat between the exhaust gas generated in the furnace 1 and water, thereby generating steam. Furthermore, for example, the boiler 100 may further include components (not shown), such as a reheater, an economizer, or an air preheater.

[0020] The flue 2 is a passage that guides the exhaust gas generated in the furnace 1 to the outside. The flue 2 is connected to the upper part of the furnace 1. For example, the flue 2 includes a first flue 2a and a second flue 2b. The first flue 2a extends horizontally from the upper part of the furnace 1. The second flue 2b extends downward from the end of the first flue 2a. For example, a pipe 2c that guides the exhaust gas to the outside is connected to the second flue 2b.

[0021] The first burner group 10 includes at least one first burner 11. In this embodiment, the first burner group 10 includes a plurality of first burners 11. The first burners 11 are provided on the side walls of the furnace 1. In this embodiment, the plurality of first burners 11 are arranged in a single row along the horizontal direction. In other embodiments, the plurality of first burners 11 may be arranged in multiple rows. For example, the plurality of first burners 11 are arranged at equal intervals in the horizontal direction. In other embodiments, the plurality of first burners 11 may be arranged at different intervals in the horizontal direction.

[0022] The first burner 11 injects a first fuel F1 containing ammonia into the combustion space S. The first fuel F1 is combusted in the combustion space S (first-stage combustion). For example, the first burner 11 is in fluid communication with a tank (ammonia supply source) 3. For example, the tank 3 stores liquid ammonia. For example, a vaporizer (not shown) may be provided in the piping between the tank 3 and the plurality of first burners 11, and gaseous ammonia may be supplied to the first burners 11. Alternatively, liquid ammonia may be supplied to the first burners 11. In another embodiment, an ammonia producer may be used as the ammonia supply source.

[0023] Air A is supplied to the first burner 11. For example, ambient air around the furnace 1 may be supplied to the first burner 11. In this embodiment, the furnace 1 includes a heat exchanger 4 for heating the air A supplied to the first burner 11 with exhaust gas Ex from the furnace 1. For example, the heat exchanger 4 may be provided on the pipe 2c. For example, the heat exchanger 4 may exchange heat between the ambient air and the exhaust gas Ex flowing through the pipe 2c. The first burner 11 may be of a premixed combustion type or a diffusion combustion type. For example, the first burner 11 may include valves for adjusting the flow rates of the first fuel F1 and the air A. These valves may be connected to the control device 90 via wire or wireless communication and may be controlled by the control device 90. For example, the control device 90 may adjust the flow rates of the first fuel F1 and the air A injected from the first burner 11 by controlling the opening degree of the valves.

[0024] The second burner group 20 includes at least one second burner 21. In this embodiment, the second burner group 20 includes a plurality of second burners 21. The second burners 21 are provided on the side wall of the furnace 1. In this embodiment, the plurality of second burners 21 are arranged in two rows along the horizontal direction. In other embodiments, the plurality of second burners 21 may be arranged in a single row, or may be arranged in three or more rows. In this embodiment, the second burner group 20 is arranged downstream of the first burner group 10. That is, in this embodiment, the plurality of second burners 21 are arranged above the plurality of first burners 11.

[0025] 2 is a schematic cross-sectional view taken along line II-II in FIG. 1, showing the arrangement of the plurality of first burners 11 and the plurality of second burners 21 on the side wall of the furnace 1. As described above, the plurality of first burners 11 are arranged in a single row at equal intervals along the horizontal direction. The plurality of second burners 21 are arranged in two rows at equal intervals along the horizontal direction. The distance between adjacent second burners 21 in the horizontal direction may be the same as or different from the distance between adjacent second burners 21 in the vertical direction.

[0026] In the present embodiment, the distance between adjacent first burners 11 is shorter than the distance between adjacent second burners 21. Specifically, in the present embodiment, the distance d1 between adjacent first burners 11 in the horizontal direction is shorter than the distance d2 between adjacent second burners 21 in the horizontal direction. With this configuration, the density of the first burners 11 increases, so that the temperature in the combustion space S in the region in front of the first burner group 10 can be increased. Therefore, the ammonia injected from the first burners 11 is heated more in the combustion space S. When the ammonia is heated, the combustibility of the ammonia is improved. Therefore, the combustibility of the ammonia injected from the first burners 11 can be improved.

[0027] Returning to Fig. 1 , the second burner 21 injects a second fuel F2 containing a fossil fuel into the combustion space S. The second fuel F2 is combusted in the combustion space S (first-stage combustion). For example, the second fuel F2 may be a by-product gas such as coke oven gas or blast furnace gas. However, the second fuel F2 is not limited thereto and may include other fuels such as pulverized coal or natural gas.

[0028] The second burner 21 is supplied with air A. For example, the second burner 21 may be supplied with ambient air around the furnace 1.

[0029] The second burner 21 is supplied with exhaust gas Ex from the furnace 1. For example, the second burner 21 may be in fluid communication with the pipe 2c, and the exhaust gas Ex flowing through the pipe 2c may be supplied to the second burner 21. That is, the exhaust gas Ex is recirculated to the combustion space S. The exhaust gas Ex may be mixed with air A before the second burner 21, or may be mixed with air A within the second burner 21, or may be supplied to the combustion space S separately from the air A. The second burner 21 may be of a premixed combustion type or a diffusion combustion type. For example, the second burner 21 may include valves for adjusting the flow rates of the second fuel F2, air A, and exhaust gas Ex. These valves may be connected to the control device 90 via wired or wireless communication and may be controlled by the control device 90. For example, the control device 90 may adjust the flow rates of the second fuel F2, air A, and exhaust gas Ex injected from the second burner 21 by controlling the opening degree of the valve.

[0030] For example, the first burner 11 and the second burner 21 may be various types of burners such as radiant cup burners or gas burners.

[0031] The airport group 30 includes at least one airport 31. In this embodiment, the airport group 30 includes a plurality of airports 31. The airport 31 is provided on a side wall of the furnace 1. In this embodiment, the plurality of airports 31 are arranged in a single row along the horizontal direction. In other embodiments, the plurality of airports 31 may be arranged in multiple rows. For example, the plurality of airports 31 are arranged at equal intervals in the horizontal direction. In other embodiments, the plurality of airports 31 may be arranged at different intervals in the horizontal direction.

[0032] For example, the airport port group 30 is disposed at a distance in the vertical direction from the second burner group 20. For example, the distance between the airport port group 30 and the second burner group 20 in the vertical direction may be longer than the distance between adjacent second burners 21 in the vertical direction. Furthermore, for example, the distance between the airport port group 30 and the second burner group 20 in the vertical direction may be longer than the distance between the second burner group 20 and the first burner group 10 in the vertical direction.

[0033] The airport 31 injects air A into the combustion space S. Unburned fuel (unburned ammonia and unburned fossil fuel) contained in the exhaust gas from the first burner group 10 and the second burner group 20 is fueled by the air A from the airport 31 (second-stage combustion). For example, ambient air around the furnace 1 may be supplied to the airport 31. In another embodiment, for example, the airport 31 may be fluidly connected to the pipe 2c, and the exhaust gas Ex flowing through the pipe 2c may be supplied to the airport 31. In this case, for example, the airport 31 may inject a mixture of ambient air and the exhaust gas Ex into the combustion space S. For example, the airport 31 may include a valve for adjusting the flow rate of the air A. The valve may be communicatively connected to the control device 90 via wire or wirelessly and may be controlled by the control device 90. For example, the control device 90 may adjust the flow rate of the air A injected from the airport 31 by controlling the opening degree of the valve.

[0034] The control device 90 controls the furnace 1. The control device 90 may also control at least some of the other components of the boiler 100. For example, the control device 90 may control the entire boiler 100. The control device 90 includes components such as a processor 90a, a storage device 90b, and a connector 90c, which are connected to each other via a bus. For example, the processor 90a includes a CPU (Central Processing Unit). For example, the storage device 90b includes a hard disk, a ROM for storing programs, and a RAM as a work area. The control device 90 is connected to each component of the furnace 1 via the connector 90c so as to be able to communicate with them via wired or wireless communication. For example, the control device 90 may further include other components, such as a display device such as a liquid crystal display or a touch panel, and an input device such as a keyboard, buttons, or a touch panel. For example, the operation of the control device 90 may be realized by the processor 90a executing a program stored in the storage device 90b.

[0035] Next, the operation of the furnace 1 will be described.

[0036] Figure 4 shows a diagram of the reaction pathway of ammonia. For example, in a typical two-stage combustion using ammonia as fuel, in order to reduce NOx, ammonia is burned in a fuel-rich combustion in the first stage, and air is supplied in the second stage to burn the unburned ammonia. Since ammonia is burned in a fuel-rich combustion in the first stage, the region between the first and second stages becomes a reduction region. In the reduction region, the decomposition rate of unburned ammonia is slow, and unburned ammonia is difficult to decompose. Unburned ammonia is burned by air supplied in the second stage, generating NOx. This is because air having a high oxygen concentration is supplied relative to the unburned ammonia, and the N in Figure 4 ２ This is because the NO reaction is dominant compared to the reaction to NO. This is because the reaction of ammonia with oxygen to form NO and the reaction of ammonia with NO to form N ２This is because, although the reaction to form NO and the reaction to form NO simultaneously occur, the reaction to form NO prevails due to the high oxygen concentration. In this embodiment, the furnace 1 is configured to reduce the unburned ammonia from the first stage in order to reduce the NOx generated in the second stage.

[0037] 1 , specifically, in this embodiment, the first burner 11 combusts a first fuel F1 containing ammonia at a first air ratio. The second burner 21 combusts a second fuel F2 containing a fossil fuel at a second air ratio higher than the first air ratio. That is, the first burner 11 combusts the first fuel F1 at a first air ratio lower than the second air ratio of the second burner 21.

[0038] With this configuration, high-temperature, low-concentration excess oxygen remains in the region in front of the second burner 21. Unburned ammonia is hardly decomposed in the reduction region where there is no oxygen, but in the region with low oxygen concentration, the N ２ The main reactions are the reaction of ammonia with oxygen to form NO, and the reaction of ammonia with NO to form N ２ However, due to the low oxygen concentration, ２ Therefore, unburned ammonia is N ２ and H ２ As a result, the amount of unburned ammonia in the exhaust gas flowing into the airport port group 30 can be reduced, and NOx generated in the second stage can be reduced.

[0039] Specifically, the first burner 11 combusts the first fuel F1 at a first air ratio greater than 0 and less than 1.0, and the second burner 21 combusts the second fuel F2 at a second air ratio greater than or equal to 1.0. More specifically, the first burner 11 may combust the first fuel F1 at a first air ratio greater than or equal to 0.6 and less than 1.0, and the second burner 21 may combust the second fuel F2 at a second air ratio greater than or equal to 1.0. Alternatively, the first burner 11 may combust the first fuel F1 at a first air ratio greater than 0 and less than 1.0, and the second burner 21 may combust the second fuel F2 at a second air ratio greater than or equal to 1.1 and less than 1.3. In addition, the first burner 11 may burn the first fuel F1 at a first air ratio that is equal to or greater than 0.6 and less than 1.0, and the second burner 21 may burn the second fuel F2 at a second air ratio that is equal to or greater than 1.1 and less than 1.3.

[0040] According to this configuration, the ammonia from the first burner 11 is burned at a first air ratio of less than 1.0, i.e., the ammonia is burned by rich combustion. This combustion suppresses the generation of NOx, but unburned ammonia remains in the area in front of the first burner 11. However, the fossil fuel from the second burner 21 is burned at a second air ratio of 1.0 or more, i.e., the fossil fuel is burned by lean combustion. Therefore, excess oxygen remains in the area in front of the second burner 21. Therefore, the unburned ammonia from the first burner 11 reacts with the excess oxygen from the second burner 21 to produce N ２ and H ２ 0. Therefore, it is possible to reduce the amount of unburned ammonia in the exhaust gas flowing into the airport port group 30, and it is possible to reduce the amount of NOx generated in the second stage.

[0041] Furthermore, in this embodiment, the air A supplied to the first burner 11 is heated by the exhaust gas Ex in the heat exchanger 4. Therefore, the ammonia supplied to the first burner 11 is heated by the air A. When the ammonia is heated, the combustibility of the ammonia is improved. Therefore, the combustibility of the ammonia in the first burner 11 is improved.

[0042] In this embodiment, the control device 90 adjusts the second air ratio of the second burner 21 according to the ammonia co-combustion ratio in the furnace 1. For example, the control device 90 may store a table indicating the relationship between the ammonia co-combustion ratio and the second air ratio in the storage device 90b, and may read the second air ratio corresponding to the ammonia co-combustion ratio from the table. For example, as the ammonia co-combustion ratio increases, the amount of unburned ammonia increases. In this case, the second burner group 20 requires more air. Therefore, as the ammonia co-combustion ratio increases, the control device 90 increases the second air ratio. In contrast, as the ammonia co-combustion ratio decreases, the control device 90 decreases the second air ratio.

[0043] Furthermore, in this embodiment, the control device 90 adjusts the second air ratios of the second burners 21 according to the concentration of unburned ammonia from the first burner 11. Specifically, since the unburned ammonia concentration is high in the region in front of the second burners 21 that are closer to the first burner 11, the control device 90 sets the second air ratios of these second burners 21 to be high. In contrast, the control device 90 sets the second air ratios of the second burners 21 that face the region with a low unburned ammonia concentration to be low. In this way, a region of oxygen concentration having a low air ratio relative to unburned ammonia is formed, and the unburned ammonia is oxidized to N while suppressing the generation of NO. ２ and H ２ In order to decompose the fuel into O, the second air ratios of the second burners 21 are adjusted.

[0044] In this embodiment, air A is supplied to the second burner 21 so that the combustion temperature in the second burner group 20 is less than 1800 K. For example, the furnace 1 may be provided with a temperature sensor (not shown) for measuring the temperature inside the furnace 1 in the area where the second burner group 20 is located. For example, the control device 90 may adjust the flow rates of air A and exhaust gas Ex so that the temperature measured by the temperature sensor is less than 1800 K. For example, when the temperature exceeds 1800 K, the control device 90 may increase the flow rate of exhaust gas Ex injected from the second burner 21. This configuration suppresses combustion of the second fuel F2 and reduces the combustion temperature. Therefore, when unburned ammonia from the first burner 11 reacts with excess oxygen from the second burner 21, the generation of thermal NOx can be reduced.

[0045] The exhaust gas from the first burner group 10 and the second burner group 20 flows into a region in front of the airport group 30. The unburned fuel (unburned ammonia and unburned fossil fuel) contained in the exhaust gas from the first burner group 10 and the second burner group 20 is completely fueled by air A from the airport 31.

[0046] The furnace 1 as described above comprises a first burner group 10 including at least one first burner 11, which injects a first fuel F1 containing ammonia into the combustion space S and burns the first fuel F1 at a first air ratio, and a second burner group 20 including at least one second burner 21, which injects a second fuel F2 containing a fossil fuel into the combustion space S and burns the second fuel F2 at a second air ratio higher than the first air ratio. With this configuration, the fossil fuel from the second burner 21 is more likely to be burned by lean combustion than the ammonia from the first burner 11. Therefore, excess oxygen is more likely to remain in the area in front of the second burner 21. Therefore, unburned ammonia contained in the exhaust gas from the first burner 11 reacts with excess oxygen from the second burner 21, and N ２ and H ２Therefore, it is possible to reduce the amount of unburned ammonia in the exhaust gas flowing into the airport port group 30, and it is possible to reduce the amount of NOx generated in the second stage.

[0047] In the furnace 1, the first air ratio is greater than 0 and less than 1.0, and the second air ratio is 1.0 or greater. With this configuration, excess oxygen remains in the region in front of the second burner 21. Therefore, unburned ammonia from the first burner 11 reacts with the excess oxygen from the second burner 21 to produce N ２ and H ２ 0. Therefore, it is possible to reduce the amount of unburned ammonia in the exhaust gas flowing into the airport port group 30, and it is possible to reduce the amount of NOx generated in the second stage.

[0048] In the furnace 1, the first air ratio may be 0.6 or more and less than 1.0, and the second air ratio may be 1.1 or more and 1.3 or less. With this configuration, it is possible to further reduce unburned ammonia in the exhaust gas and further reduce NOx generated in the second stage.

[0049] The furnace 1 also includes a control device 90 that controls the second burner group 20. The control device 90 adjusts the second air ratio according to the ammonia co-firing ratio. For example, as the ammonia co-firing ratio increases, the amount of unburned ammonia increases. With the above-described configuration, the second air ratio can be adjusted according to the ammonia co-firing ratio, i.e., the amount of unburned ammonia.

[0050] In the furnace 1, air is supplied to the second burner 21 so that the combustion temperature of the second fuel F2 is less than 1800 K. With this configuration, when unburned ammonia from the first burner 11 reacts with excess oxygen from the second burner 21, the generation of thermal NOx can be reduced.

[0051] In the furnace 1, the exhaust gas Ex from the furnace 1 is supplied to the second burner 21. With this configuration, the combustion temperature of the second fuel F2 can be controlled by adjusting the amount of the exhaust gas Ex. Therefore, when unburned ammonia from the first burner 11 reacts with excess oxygen from the second burner 21, the generation of thermal NOx can be reduced.

[0052] The furnace 1 also includes a heat exchanger 4 for heating the air A supplied to the first burner 11 with the exhaust gas Ex from the furnace 1. With this configuration, the combustibility of ammonia in the first burner 11 is improved.

[0053] Furthermore, in the furnace 1, the first burner group 10 includes a plurality of first burners 11, and the second burner group 20 includes a plurality of second burners 21, and the distance d1 between adjacent first burners 11 is shorter than the distance d2 between adjacent second burners 21. With this configuration, the density of the first burners 11 increases, so the temperature in the combustion space S in the region in front of the first burner group 10 can be increased. Therefore, the ammonia injected from the first burners 11 is heated more in the combustion space S. When the ammonia is heated, the combustibility of the ammonia is improved. Therefore, the combustibility of the ammonia injected from the first burners 11 can be improved.

[0054] For example, the furnace 1 described above may be constructed by modifying an existing furnace that uses fossil fuel. For example, piping for supplying ammonia may be added to some or all of the multiple burners that burn fossil fuel. In this case, some of the multiple burners may be used as second burners 21, and some or all of the remaining burners may be used as first burners 11.

[0055] Although the embodiments have been described above with reference to the accompanying drawings, the present disclosure is not limited to the above-described embodiments. It is clear that a person skilled in the art can conceive of various modifications or alterations within the scope of the claims, and it is understood that such modifications also fall within the technical scope of the present disclosure.

[0056] For example, in the above embodiment, the furnace 1 is applied to the boiler 100. In other embodiments, the furnace 1 may be applied to other facilities.

[0057] 3 is a schematic cross-sectional view of a naphtha cracking furnace 200 including a furnace 1A according to another embodiment. The furnace 1A differs from the furnace 1 according to the above embodiment in that the furnace 1A is applied to the naphtha cracking furnace 200 and further includes a floor burner 41. The other configurations of the furnace 1A may be the same as those of the furnace 1.

[0058] The naphtha cracking furnace 200 is provided with piping (not shown) through which naphtha passes. The exhaust gas is led to the outside through piping 2c.

[0059] The floor burner 41 is provided on the floor wall of the furnace 1A. In this embodiment, the floor burner 41, like the first burner 11, injects a first fuel F1 containing ammonia into the combustion space S and burns the first fuel F1 at a first air ratio. For example, the floor burner 41 is in fluid communication with the tank 3. In another embodiment, the floor burner 41, like the second burner 21, may inject a second fuel F2 containing a fossil fuel into the combustion space S and burn the second fuel F2 at a second air ratio.

[0060] In the naphtha cracking furnace 200, naphtha passing through a pipe (not shown) is heated by exhaust gas generated by the combustion of the first fuel F1 and the second fuel F2, and is distilled into a plurality of components. Such a furnace 1A has substantially the same effects as the furnace 1 according to the above embodiment.

[0061] Furthermore, in the above embodiment, the first burner group 10 is arranged upstream of the second burner group 20, i.e., the multiple first burners 11 are arranged below the multiple second burners 21. The arrangement of the first burners 11 and the second burners 21 is not limited to this. For example, the first burner group 10 may be arranged downstream of the second burner group 20, i.e., the multiple first burners 11 may be arranged above the multiple second burners 21. Furthermore, for example, the first burners 11 and the second burners 21 may be arranged alternately with each other in at least one of the vertical and horizontal directions.

[0062] In the above embodiment, the furnace 1 also includes an air port group 30. In another embodiment, the unburned ammonia from the first burner group 10 is sufficiently converted into N by the second burner group 20. ２ and H ２ If the temperature can be decomposed into 0, the furnace 1 does not need to include the air port group 30.

[0063] In the above embodiment, the furnace 1 includes a plurality of first burners 11 to which a first fuel F1 containing ammonia and air A are supplied, and a plurality of second burners 21 to which a second fuel F2 containing a fossil fuel, air A, and exhaust gas Ex are supplied. That is, in the above embodiment, the first burners 11 and the second burners 21 have different functions. In other embodiments, the furnace 1 may include a plurality of burners having the same function and selectively supplied with the first fuel F1, the second fuel F2, air A, and exhaust gas Ex, and some of the plurality of burners may be used as the first burners 11, and some or all of the remaining burners may be used as the second burners 21.

[0064] The present disclosure provides ２ It can promote the use of ammonia, which leads to reduced emissions, thereby contributing, for example, to Sustainable Development Goal (SDG) 7 "Ensure access to affordable, reliable, sustainable and modern energy" and SDG 13 "Take urgent action to combat climate change and its impacts".

[0065] REFERENCE SIGNS LIST 1 Furnace 1A Furnace 4 Heat exchanger 10 First burner group 11 First burner 20 Second burner group 21 Second burner 90 Control device d1 Distance between adjacent first burners d2 Distance between adjacent second burners Ex Exhaust gas F1 First fuel F2 Second fuel S Combustion space

Claims

1. A furnace comprising: a first burner group including at least one first burner, the at least one first burner injecting a first fuel including ammonia into a combustion space and combusting the first fuel at a first air ratio; and a second burner group including at least one second burner, the at least one second burner injecting a second fuel including a fossil fuel into a combustion space and combusting the second fuel at a second air ratio higher than the first air ratio.

2. The furnace of claim 1, wherein said first air ratio is greater than 0 and less than 1.0, and said second air ratio is greater than or equal to 1.

0.

3. The furnace according to claim 2, wherein the first air ratio is greater than or equal to 0.6 and less than 1.0, and the second air ratio is greater than or equal to 1.1 and less than or equal to 1.

3.

4. The furnace according to claim 1, further comprising a control device for controlling said second burner group, said control device adjusting said second air ratio in accordance with an ammonia co-firing ratio in said furnace.

5. The furnace of claim 1, wherein said at least one second burner is supplied with air such that the combustion temperature of said second fuel is less than 1800K.

6. The furnace of claim 5, wherein said at least one second burner is supplied with exhaust gas from said furnace.

7. A furnace according to claim 1, comprising a heat exchanger for heating air supplied to said at least one first burner by exhaust gas from said furnace.

8. The furnace of claim 1, wherein the first burner group includes a plurality of first burners, and the second burner group includes a plurality of second burners, and the distance between adjacent first burners of the plurality of first burners is less than the distance between adjacent second burners of the plurality of second burners.

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