Burner

Abstract

To reduce a NOx value in exhaust gas exhausted to the outside of a furnace.SOLUTION: A burner 100 includes: a flame holding channel 122 communicating with an internal space 20 of a furnace 10; a fuel injection port 162 opening into the flame holding channel 122 and facing the internal space 20 of the furnace 10; an oxygen-containing gas injection port 150 opening into the flame holding channel 122 and provided toward the internal space 20 of the furnace 10 while being separated from the fuel injection port 162; a flame stabilizer 140 provided between the fuel injection port 162 and the oxygen-containing gas injection port 150; and a throttle 130 provided closer to the internal space 20 of the furnace 10 than the fuel injection port 162, the oxygen-containing gas injection port 150, and the flame stabilizer 140, and having a converging port 134 smaller than a channel cross-sectional area of the flame holding channel 122.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a burner. [Background technology]

[0002] In recent years, there has been a demand for reducing CO2 (carbon dioxide) emissions to prevent global warming. For this reason, technology for burning hydrogen instead of hydrocarbon fuel gases such as city gas has been attracting attention (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2023-163435 Summary of the Invention [Problem to be solved by the invention]

[0004] The flame temperature when burning hydrogen is higher than the flame temperature when burning hydrocarbon fuel gas. In a high-temperature atmosphere, nitrogen oxides (hereinafter referred to as "thermal NOx") generated by the reaction between nitrogen and oxygen in the air increase. Therefore, in a burner that burns hydrogen, the high flame temperature increases thermal NOx, which causes a problem of an increase in the concentration of nitrogen oxides in the exhaust gas (hereinafter referred to as "NOx value").

[0005] In view of the above problems, the present invention has an object to provide a burner capable of reducing the NOx value in the exhaust gas discharged outside the furnace. [Means for solving the problem]

[0006] As a result of extensive research into solving the above problems, the inventors of the present invention came up with the idea that in order to reduce the NOx value in the exhaust gas discharged outside the furnace to below the NOx emission standard value of the Air Pollution Control Act, if it were possible to increase the injection flow rate of the mixed gas containing unburned hydrogen and air that is injected from the burner into the furnace while reducing the mixability of the injected hydrogen and air inside the tip of the burner, a recirculation flow would be generated within the furnace, causing the hydrogen to burn slowly and lowering the flame temperature, making it possible to reduce the NOx value in the exhaust gas discharged outside the furnace to below the emission standard value.

[0007] That is, in order to solve the above problems, the burner of the present invention comprises a flame holding flow path communicating with the internal space of the furnace, a fuel injection port that opens into the flame holding flow path and is provided facing the internal space of the furnace, an oxygen-containing gas injection port that opens into the flame holding flow path and is provided away from the fuel injection port and facing the internal space of the furnace, a flame stabilizer that is provided between the fuel injection port and the oxygen-containing gas injection port, and a throttle that is provided closer to the internal space of the furnace than the fuel injection port, the oxygen-containing gas injection port, and the flame stabilizer and has a converging port that is smaller than the flow cross-sectional area of ​​the flame holding flow path.

[0008] The flame stabilizer may also include a flame stabilizer plate having a flat surface facing the convergence port, and the diameter of the convergence port may be smaller than the outer diameter of the flame stabilizer plate.

[0009] The diameter of the converging port may be 4 / 5 or less of the outer diameter of the flame stabilizing plate.

[0010] The axial length of the flame-stabilizing flow passage may be 1 / 2 or more and 1.5 or less times the smallest diameter of the flame-stabilizing flow passages.

[0011] The combustion chamber may also be provided with a flame stabilizing tube that forms a flame stabilizing flow path, the outer surface of the flame stabilizing plate being separated from the inner surface of the flame stabilizing tube, and the gap formed between the outer surface of the flame stabilizing plate and the inner surface of the flame stabilizing tube may include an oxygen-containing gas injection port.

[0012] The flame stabilizer may also include a flame stabilizer plate having a flat surface facing the convergence port, and may be provided with a fuel injection nozzle having a fuel injection port and penetrating the flame stabilizer plate.

[0013] The fuel injection port may face the convergent port.

[0014] The flame-holding channel may also have a constant diameter along the axial direction. [Effects of the Invention]

[0015] According to the present invention, it is possible to reduce the NOx value in the exhaust gas discharged to the outside of the furnace. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a diagram illustrating a burner according to an embodiment. [Figure 2] FIG. 2 is a diagram illustrating a flame stabilizer and a fuel injection nozzle according to the first embodiment. [Figure 3] FIG. 3 is a graph showing the amount of NOx produced in the first embodiment. [Figure 4] FIG. 4 is a diagram illustrating the fuel injection nozzles of the second embodiment and the second embodiment. [Figure 5] FIG. 5 is a graph showing the amount of NOx produced in the second embodiment. [Figure 6] FIG. 6 is a graph showing the amount of NOx produced in the third embodiment. [Figure 7] FIG. 7 is a graph showing the amount of NOx produced in the fourth embodiment. [Figure 8] FIG. 8 is a diagram showing the simulation results of Example 5A. [Figure 9] FIG. 9 is a diagram showing the simulation results of Example 5B. DETAILED DESCRIPTION OF THE INVENTION

[0017] Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Dimensions, materials, and other specific values ​​shown in the embodiments are merely examples for facilitating understanding of the invention and, unless otherwise specified, do not limit the present invention. 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 invention are not shown.

[0018] FIG. 1 is a diagram illustrating a burner 100 according to this embodiment. The burner 100 according to this embodiment burns a fuel gas with oxygen contained in an oxygen-containing gas. The oxygen-containing gas is a gas containing oxygen, such as air, oxygen-enriched gas, or oxygen. In this embodiment, air is used as an example of the oxygen-containing gas. The burner 100 according to this embodiment also burns a single fuel gas or a mixture of multiple fuel gases with different combustion rates. The fuel gas is, for example, one or both of hydrogen and hydrocarbon-based fuel gas. The burner 100 according to this embodiment may burn hydrogen as the fuel gas, a hydrocarbon-based fuel gas as the fuel gas, or a mixed fuel gas of hydrogen and hydrocarbon-based fuel gas as the fuel gas. The hydrocarbon-based fuel gas is a gas containing hydrocarbons, such as city gas.

[0019] As shown in FIG. 1, the burner 100 according to this embodiment includes an outer tube 110, a flame stabilizing tube 120, a restrictor 130, a flame stabilizer 140, an oxygen-containing gas injection port 150, a fuel injection nozzle 160, a fuel gas supply unit 170, and an oxygen-containing gas supply unit 180.

[0020] The outer tube 110 is, for example, cylindrical, and has, in order from the inner space 20 side of the furnace 10, a reduced diameter portion 110a, a large diameter portion 110b, an expanded diameter portion 110c, and a base end portion 110d. The reduced diameter portion 110a and a portion of the large diameter portion 110b are provided, for example, within the refractory wall 12 that constitutes the furnace 10.

[0021] One end of the reduced diameter section 110a (the tip of the outer tube 110) on the inner space 20 side of the furnace 10 is continuous with the flame stabilization tube 120 described below. The other end of the reduced diameter section 110a is continuous with the large diameter section 110b. The inner diameter of the reduced diameter section 110a gradually decreases from the large diameter section 110b side toward the flame stabilization tube 120 side.

[0022] One end of the large diameter portion 110b, which faces the internal space 20 of the furnace 10, is continuous with the reduced diameter portion 110a. The other end of the large diameter portion 110b is continuous with the expanded diameter portion 110c. The inner diameter of the large diameter portion 110b is substantially constant. The inner diameter of the large diameter portion 110b is larger than the inner diameter of the flame stabilization tube 120.

[0023] One end of the expanded diameter portion 110c, which faces the internal space 20 of the furnace 10, is continuous with the large diameter portion 110b. The other end of the expanded diameter portion 110c is continuous with the base end 110d. The inner diameter of the expanded diameter portion 110c gradually increases from the base end 110d side toward the large diameter portion 110b side.

[0024] One end of the base end 110d, which is on the inner space 20 side of the furnace 10, is continuous with the expanded diameter portion 110c. The other end of the base end 110d is connected to the oxygen-containing gas supply unit 180, which will be described later. The inner diameter of the base end 110d is approximately constant. The inner diameter of the base end 110d is smaller than the inner diameter of the large diameter portion 110b.

[0025] The flame stabilization tube 120 is continuous with the reduced diameter portion 110a of the outer tube 110 (the tip of the outer tube 110) and communicates with the internal space 20 of the furnace 10. The flame stabilization tube 120 is, for example, cylindrical. A flame stabilization flow path 122 is formed inside the flame stabilization tube 120. The flame stabilization flow path 122 is a flow path in which a portion of the fuel gas is mixed with air. The diameter D of the flame stabilization flow path 122 is, for example, constant along the axial direction. In other words, the inner diameter of the flame stabilization tube 120 according to this embodiment is constant along the axial direction.

[0026] Furthermore, in this embodiment, the axial length L of the flame stability channel 122 is, for example, 1 / 2 to 1.5 times the smallest diameter among the diameters D of the flame stability channel 122. As described above, in this embodiment, the diameter D of the flame stability channel 122 is constant along the axial direction, and therefore the axial length L of the flame stability channel 122 is, for example, 1 / 2 to 1.5 times the diameter D of the flame stability channel 122. In other words, the axial length of the flame stability tube 120 according to this embodiment is 1 / 2 to 1.5 times the inner diameter of the flame stability tube 120.

[0027] The orifice 130 is provided, for example, at the tip of the flame stabilizing tube 120. The orifice 130 may be formed integrally with the flame stabilizing tube 120, or may be separate from the flame stabilizing tube 120. The orifice 130 includes a orifice plate 132 and a converging port 134. The orifice plate 132 is a plate having an outer shape that follows the inner shape of the flame stabilizing tube 120, and is, for example, a circular plate. The converging port 134 is an opening formed approximately in the center of the orifice plate 132. The opening area of ​​the converging port 134 is smaller than the flow path cross-sectional area of ​​the flame stabilizing channel 122. In other words, the opening diameter F of the converging port 134 is smaller than the diameter D of the flame stabilizing channel 122.

[0028] Flame stabilizer 140 is provided in flame-stabilizing flow path 122. Flame stabilizer 140 includes a flame stabilizer plate 142. Flame stabilizer plate 142 is, for example, a circular plate. Flame stabilizer plate 142 has a flat surface 142a. Flat surface 142a is provided facing convergent port 134 of orifice 130. Furthermore, flame stabilizer plate 142 has a through-hole 142b formed in approximately the center thereof. The outer edge shape of through-hole 142b is substantially equal to the outer diameter shape of fuel injection nozzle 160, which will be described later.

[0029] Furthermore, in this embodiment, the outer diameter E of the flame stabilizing plate 142 is larger than the aperture diameter F of the converging port 134. In other words, the aperture diameter F of the converging port 134 may be smaller than the outer diameter E of the flame stabilizing plate 142. For example, the aperture diameter F of the converging port 134 is preferably 4 / 5 or less of the outer diameter E of the flame stabilizing plate 142. Furthermore, the aperture diameter F of the converging port 134 is preferably equal to or larger than the hole diameter of the through-hole 142b of the flame stabilizing plate 142 (i.e., the outer diameter of the fuel injection nozzle 160, which will be described later), or equal to or larger than the aperture diameter of the fuel injection port 162.

[0030] Although not shown in the drawings, in this embodiment, flame stabilizing plate 142 is provided with a plurality of air holes arranged radially from the center of flame stabilizing plate 142. This allows a portion of the fuel gas and air to be mixed to a combustible state in flame stabilizing channel 122, and a portion of the fuel gas begins to burn. The ratio of the opening area of ​​the plurality of air holes is preferably 10% or less of the entire area of ​​flame stabilizing plate 142, for example, 1 to 5%.

[0031] In this embodiment, the outer peripheral surface of the flame stabilizing plate 142 is separated from the inner peripheral surface of the flame stabilizing tube 120. A gap formed between the outer peripheral surface of the flame stabilizing plate 142 and the inner peripheral surface of the flame stabilizing tube 120 functions as an oxygen-containing gas injection port 150.

[0032] The oxygen-containing gas injection port 150 opens into the flame-stabilizing flow path 122 and is provided away from the fuel injection port 162 (described later) toward the internal space 20 of the furnace 10. Air is injected from the oxygen-containing gas injection port 150 into the flame-stabilizing flow path 122.

[0033] The distance between the inner peripheral surface of the flame stabilization tube 120 and the outer peripheral surface of the flame stabilization plate 142, i.e., the opening area of ​​the oxygen-containing gas injection port 150, is appropriately designed according to the desired air flow velocity. For example, the opening area of ​​the oxygen-containing gas injection port 150 is designed to be small enough so that the air flow velocity does not decrease due to pressure loss.

[0034] The fuel injection nozzle 160 is a nozzle that injects fuel gas into the flame stabilization flow path 122. The fuel injection nozzle 160 is, for example, cylindrical. The fuel injection nozzle 160 is provided inside the outer tube 110 and inside the flame stabilization tube 120. The fuel injection nozzle 160 penetrates the flame stabilization plate 142. As described above, in this embodiment, a through-hole 142b is formed in the approximate center of the flame stabilization plate 142, and the fuel injection nozzle 160 penetrates through the through-hole 142b of the flame stabilization plate 142. The gap between the fuel injection nozzle 160 and the through-hole 142b is preferably small enough to prevent air from leaking out, and is, for example, about 1 mm. The tip of the fuel injection nozzle 160 is disposed inside the flame stabilization tube 120.

[0035] A fuel injection port 162 is formed at the tip of the fuel injection nozzle 160. The fuel injection port 162 opens into the flame stabilization channel 122 and is provided facing the internal space 20 of the furnace 10. In this embodiment, the fuel injection port 162 is provided coaxially with the convergent port 134 of the orifice 130 and faces the convergent port 134 of the orifice 130. In other words, the fuel injection port 162 is disposed on the central axis of the convergent port 134. In addition, the injection direction of the fuel injection port 162 is approximately parallel to the injection direction of the oxygen-containing gas injection port 150.

[0036] The fuel gas supply unit 170 supplies fuel gas to the fuel injection nozzle 160. The fuel gas supply unit 170 includes, for example, a fuel supply system. The fuel gas supplied to the fuel injection nozzle 160 by the fuel gas supply unit 170 is injected from the fuel injection port 162 into the flame stabilization channel 122 and sent to the inner space 20 of the furnace 10 through the convergence port 134.

[0037] The oxygen-containing gas supply unit 180 supplies air to the outer tube 110. The oxygen-containing gas supply unit 180 includes, for example, an oxygen-containing gas supply system. The air supplied to the outer tube 110 by the oxygen-containing gas supply unit 180 is injected from the oxygen-containing gas injection port 150 into the flame stabilization channel 122 and flows along the inner circumferential surface of the flame stabilization tube 120 toward the furnace 10. However, the orifice 130 causes the air to flow toward the flame stabilization plate 142, forming a circulating flow within the flame stabilization channel 122. The air is then sent to the interior space 20 of the furnace 10 through the convergence port 134.

[0038] At the start of combustion, a portion of the mixed gas of fuel gas and air in the flame-holding flow path 122 that has been mixed to a combustible state is ignited by an ignition device (not shown), and a flame is formed toward the internal space 20 of the furnace 10.

[0039] As described above, the burner 100 of this embodiment comprises a flame-holding passage 122 communicating with the internal space 20 of the furnace 10, a fuel injection port 162 opening into the flame-holding passage 122 and facing the internal space 20 of the furnace 10, an oxygen-containing gas injection port 150 opening into the flame-holding passage 122 and facing the internal space 20 of the furnace 10 at a distance from the fuel injection port 162, a flame stabilizer 140 provided between the fuel injection port 162 and the oxygen-containing gas injection port 150, and a throttle 130 provided closer to the internal space 20 of the furnace 10 than the fuel injection port 162, the oxygen-containing gas injection port 150, and the flame stabilizer 140, and having a converging port 134 smaller than the cross-sectional area of ​​the flame-holding passage 122.

[0040] As described above, the burner 100 according to the present embodiment, by including the orifice 130, can increase the injection flow velocity of the fuel gas and air mixed gas into the internal space 20 of the furnace 10 compared to a case without the orifice 130. This allows the burner 100 according to the present embodiment to form a recirculation flow toward the burner 100 in the internal space 20 of the furnace 10, which is an open space. By forming a recirculation flow, the exhaust gas in the furnace 10 can be mixed into the mixed gas. Since the exhaust gas in the furnace 10 has a lower oxygen concentration than unreacted air, mixing the exhaust gas into the mixed gas can reduce the oxygen concentration of the mixed gas. This allows the burner 100 according to the present embodiment to slow the reaction rate between the fuel gas and oxygen, enabling slow combustion. Therefore, the burner 100 according to the present embodiment can burn the fuel gas while maintaining a low flame temperature. Therefore, the burner 100 according to this embodiment can keep the flame temperature low whether it burns a hydrocarbon fuel gas, whether it burns hydrogen, which has a higher flame temperature than a hydrocarbon fuel gas, or whether it burns a mixture of hydrocarbon fuel gas and hydrogen. Therefore, the burner 100 according to this embodiment can reduce the NOx value in the exhaust gas discharged outside the furnace 10, regardless of the type of fuel gas. In other words, the burner 100 according to this embodiment can reduce the NOx value in the exhaust gas discharged outside the furnace 10 even when it burns hydrogen, which has a higher flame temperature than a hydrocarbon fuel gas, as the fuel gas.

[0041] Furthermore, the burner 100 according to this embodiment is provided with the orifice 130, which makes it possible to increase the strength of the vortex of the circulating air flow formed downstream of the flame stabilization plate 142 in the flame stabilization channel 122. The vortex strength is defined as "vortex strength = vortex flow velocity / vortex size." As a result, the burner 100 according to this embodiment achieves slow combustion that can reduce NOx values ​​by injecting the fuel gas and air into the furnace 10 in the flame stabilization channel 122 without excessively mixing them to an optimal state for combustion. In other words, the circulating flow does not significantly affect the flow of fuel gas injected from the single fuel injection port 162 located on the central axis of the flame stabilization channel 122. This makes it possible to stabilize the flame and ensure flame stability whether burning hydrogen, a hydrocarbon fuel gas with a lower combustion rate than hydrogen, or a mixture of hydrogen and hydrocarbon fuel gas. Therefore, the burner 100 according to this embodiment can stabilize the flame and ensure flame stability regardless of the type of fuel gas. In other words, the burner 100 according to this embodiment can stabilize the flame and ensure flame stability even when burning a hydrocarbon fuel gas, which has a lower combustion speed than hydrogen, as the fuel gas.

[0042] In this way, by providing the orifice 130, the burner 100 according to this embodiment can achieve both a reduction in the NOx value in the exhaust gas and the assurance of flame stability, even when burning either or both of hydrogen and hydrocarbon-based fuel gases, which have different flame temperatures and combustion speeds.

[0043] Furthermore, as described above, in the burner 100 according to this embodiment, the flame stabilizer 140 includes a flame stabilizer plate 142 having a flat surface 142a facing the convergence port 134, and the diameter F of the convergence port 134 may be smaller than the outer diameter E of the flame stabilizer plate 142.

[0044] As a result, the burner 100 according to this embodiment can further increase the injection flow rate of the mixed gas of fuel gas and air into the internal space 20 of the furnace 10. Furthermore, the burner 100 according to this embodiment can form a circulating flow with stronger vortex strength in the flame stabilization flow path 122. Therefore, the burner 100 according to this embodiment can further achieve both low NOx in the exhaust gas and ensure flame stabilization.

[0045] Furthermore, as described above, in the burner 100 according to this embodiment, the diameter F of the converging port 134 of the restrictor 130 may be 4 / 5 or less of the outer diameter E of the flame stabilizing plate 142.

[0046] As a result, the burner 100 according to this embodiment can further increase the injection flow rate of the mixed gas of fuel gas and air into the internal space 20 of the furnace 10. Furthermore, the burner 100 according to this embodiment can preferably form a circulating flow with a stronger vortex in the flame stabilization flow path 122. Therefore, the burner 100 according to this embodiment can further achieve both a reduction in the NOx value in the exhaust gas and the assurance of flame stabilization.

[0047] Furthermore, as described above, in the burner 100 according to this embodiment, the axial length L of the flame holding channel 122 may be 1 / 2 or more and 1.5 or less times the smallest diameter D of the flame holding channel 122.

[0048] By setting the axial length L of the flame holding channel 122 to at least half the smallest diameter D of the flame holding channel 122, a circulating air flow can be reliably formed within the flame holding channel 122. Therefore, the burner 100 according to this embodiment can ensure the ignition of the fuel gas even when using a hydrocarbon fuel gas, which has a lower combustion speed than hydrogen, as the fuel gas. Furthermore, by setting the axial length L of the flame holding channel 122 to at most 1.5 times the smallest diameter D of the flame holding channel 122, the burner 100 according to this embodiment can suppress the progress of the combustion reaction within the flame holding channel 122, and can reduce the NOx value in the exhaust gas even when using hydrogen as the fuel gas.

[0049] In this way, in the burner 100 according to this embodiment, by setting the axial length L of the flame stabilization flow path 122 to be between 1 / 2 and 1.5 times the smallest diameter D of the flame stabilization flow path 122, it is possible to ensure flame stability and reduce the NOx value in the exhaust gas, whether hydrogen or a hydrocarbon fuel gas is used as the fuel gas.

[0050] As described above, the burner 100 according to this embodiment includes a flame stabilization tube 120 that forms a flame stabilization flow path 122, and the outer peripheral surface of the flame stabilization plate 142 is separated from the inner peripheral surface of the flame stabilization tube 120. The gap formed between the outer peripheral surface of the flame stabilization plate 142 and the inner peripheral surface of the flame stabilization tube 120 may include an oxygen-containing gas injection port 150. In this way, the burner 100 according to this embodiment can reduce the flow path cross-sectional area of ​​the oxygen-containing gas injection port 150 by narrowing the gap formed between the outer peripheral surface of the flame stabilization plate 142 and the inner peripheral surface of the flame stabilization tube 120, thereby making it possible to increase the air flow velocity. Therefore, the burner 100 according to this embodiment can form a negative pressure region in the flame stabilization flow path 122 downstream of the flame stabilization plate 142, making it possible to favorably form a circulating air flow. As a result, the burner 100 according to this embodiment can stabilize the flame and further improve flame stability even when burning a hydrocarbon fuel gas, which has a lower combustion speed than hydrogen, as the fuel gas.

[0051] Furthermore, as described above, in the burner 100 according to this embodiment, the flame stabilizer 140 includes a flame stabilizer plate 142 having a flat surface 142a facing the convergence port 134, and the burner 100 may include a fuel injection nozzle 160 having a fuel injection port 162 and penetrating the flame stabilizer plate 142. A gap may be provided between the flame stabilizer plate 142 and the fuel injection nozzle 160 to prevent air from leaking into the flame-stabilizing flow path 122. In this way, unlike when the gap between the flame stabilizer plate 142 and the fuel injection nozzle 160 is large, the burner 100 according to this embodiment can prevent air from being injected into the flame-stabilizing flow path 122 through the gap. Therefore, the burner 100 according to this embodiment forms a circulating flow with a strong vortex in the flame-stabilizing flow path 122, suppressing excessive mixing of the fuel gas and air and enabling slow combustion. Therefore, the burner 100 according to this embodiment can burn the fuel gas while maintaining a low flame temperature. As a result, the burner 100 according to this embodiment can reduce the NOx value in the exhaust gas even when burning hydrogen, which has a higher flame temperature than hydrocarbon fuel gas, as the fuel gas.

[0052] Furthermore, as described above, in the burner 100 according to this embodiment, the fuel injection port 162 may face the convergent port 134. This allows the burner 100 according to this embodiment to make the flow of fuel gas and the flow of air approximately parallel, thereby preventing the fuel gas and air from being mixed more than necessary and enabling slow combustion. Therefore, the burner 100 according to this embodiment can burn the fuel gas while keeping the flame temperature low. Therefore, the burner 100 according to this embodiment can reduce the NOx value in the exhaust gas even when burning hydrogen as the fuel gas, which has a higher flame temperature than hydrocarbon fuel gas.

[0053] Furthermore, as described above, in the burner 100 according to this embodiment, the diameter of the flame stabilization channel 122 may be constant along the axial direction. For example, in a comparative example in which the cross-sectional area of ​​the channel gradually increases toward the internal space 20 of the furnace 10, the burner 100 according to this embodiment can increase the air flow velocity more than the comparative example. Therefore, the burner 100 according to this embodiment can form a negative pressure region in the flame stabilization channel 122 downstream of the flame stabilization plate 142, and can form a circulating air flow. As a result, the burner 100 according to this embodiment can stabilize the flame and ensure flame stability even when burning a hydrocarbon fuel gas, which has a lower combustion speed than hydrogen, as the fuel gas. [Example]

[0054] [First Example] In order to examine the protrusion amount of the fuel injection nozzle 160 relative to the flame stabilizing plate 142, burners of Examples 1A to 1C were produced as a first example, and the amount of NOx produced was measured.

[0055] FIG. 2 is a diagram illustrating the flame stabilizer 142 and fuel injection nozzle 160 of the first embodiment. As shown in FIG. 2, the burner of embodiment 1A is the same as the burner 100 described above. In the burner of embodiment 1B, the tip of the fuel injection nozzle 160 is pushed toward the convergence port 134 side with respect to the flame stabilizer 142, as compared with embodiment 1A. In the burners of embodiments 1A and 1B, the fuel injection nozzle 160 passes through the through-hole 142b of the flame stabilizer 142 without any gaps. Therefore, in the burners of embodiments 1A and 1B, air is injected into the flame stabilizer channel 122 only from the oxygen-containing gas injection port 150.

[0056] On the other hand, in the burner of Example 1C, compared to the burner of Example 1A, the tip of the fuel injection nozzle 160 is retracted on the opposite side of the convergence port 134 with the flame stabilizer 142 as the reference. In the burner of Example 1C, the tip of the fuel injection nozzle 160 (fuel injection port 162) is separated from the through-hole 142b of the flame stabilizer 142. Therefore, in the burner of Example 1C, air is injected into the flame stabilizing flow path 122 from the through-hole 142b of the flame stabilizer 142 in addition to the oxygen-containing gas injection port 150.

[0057] Figure 3 is a graph showing the amount of NOx generated in Example 1. In Figure 3, the vertical axis represents the dimensionless amount of NOx, and the horizontal axis represents the co-firing ratio (hereinafter simply referred to as "co-firing ratio") [%] based on the calorific value of hydrogen relative to the combined calorific value of city gas and hydrogen. In Figure 3, white circles represent Example 1A, white squares represent Example 1B, and black circles represent Example 1C.

[0058] Note that a hydrogen co-firing ratio of 0% indicates that the fuel gas contains 100% city gas. A hydrogen co-firing ratio of 50% indicates that the fuel gas contains 50% hydrogen and 50% city gas. A hydrogen co-firing ratio of 100% indicates that the fuel gas contains 100% hydrogen.

[0059] 3, it was confirmed that Examples 1A and 1B produced lower amounts of NOx compared to Example 1C, regardless of the hydrogen co-firing ratio. This result shows that by eliminating the gap between the flame stabilizing plate 142 and the fuel injection nozzle 160, it is possible to reduce NOx in the exhaust gas even when burning either or both of hydrogen and city gas, which have different flame temperatures.

[0060] It was also confirmed that there was almost no difference in the amount of NOx generated between Example 1A and Example 1B. From this result, it was found that if there is no gap between the flame stabilizing plate 142 and the fuel injection nozzle 160, it is possible to reduce NOx in the exhaust gas regardless of the push-out amount of the fuel injection nozzle 160.

[0061] [Second Example] In order to examine the orientation of the fuel injection port 162, burners of Examples 2A and 2B were produced as a second example, and the amount of NOx produced was measured.

[0062] 4 is a diagram illustrating a fuel injection nozzle 160 of Example 2A and Example 2B. As shown in FIG. 4, the burner of Example 2A is the same as the burner 100. In the burner of Example 2A, the injection direction of the fuel injection port 162 is approximately parallel to the injection direction of the oxygen-containing gas injection port 150.

[0063] The burner of Example 2B has fuel injection ports 162a and 162b, as compared to Example 2A. Like the fuel injection port 162 of the burner of Example 2A, the fuel injection port 162a faces the convergent port 134. The injection direction of the fuel injection port 162a is approximately parallel to the injection direction of the oxygen-containing gas injection port 150. On the other hand, the fuel injection port 162b is arranged in a direction intersecting with the central axis of the fuel injection port 162a. The injection direction of the fuel injection port 162b intersects with the injection direction of the oxygen-containing gas injection port 150. Therefore, in the flame holding channel 122, the fuel gas injected from the fuel injection port 162b collides with the air injected from the oxygen-containing gas injection port 150.

[0064] The opening area of ​​the fuel injection port 162 in Example 2A is substantially equal to the sum of the opening areas of the fuel injection port 162a and the fuel injection port 162b in Example 2B.

[0065] Figure 5 is a graph showing the amount of NOx generated in Example 2. In Figure 5, the vertical axis represents the dimensionless amount of NOx, and the horizontal axis represents the hydrogen co-firing ratio [%] relative to the combined calorific value of city gas and hydrogen. Also, in Figure 5, white circles represent Example 2A, and black circles represent Example 2B.

[0066] As shown in Figure 5, Example 2A produced less NOx than Example 2B, regardless of the hydrogen co-firing ratio. This result shows that by making the fuel gas flow and the air flow approximately parallel, it is possible to reduce NOx in the exhaust gas even when burning either or both of hydrogen and city gas, which have different flame temperatures.

[0067] [Third Example] In order to examine the dimensional relationship between the diameter F of the converging port 134 of the orifice 130 and the outer diameter E of the flame stabilizing plate 142, burners of Examples 3A to 3C were produced as the third example, and the amount of NOx generated was measured.

[0068] In Example 3A, the diameter F of converging port 134 of orifice 130 was set to 1 time the outer diameter E of flame stabilizing plate 142. In Example 3B, the diameter F of converging port 134 of orifice 130 was set to 4 / 5 times the outer diameter E of flame stabilizing plate 142. In Comparative Example 3C, the diameter F of converging port 134 of orifice 130 was set to 4 / 3 times the outer diameter E of flame stabilizing plate 142.

[0069] Figure 6 is a graph showing the amount of NOx generated in Example 3. In Figure 6, the vertical axis represents the dimensionless amount of NOx, and the horizontal axis represents the hydrogen co-firing ratio [%] relative to the combined calorific value of city gas and hydrogen. In Figure 6, white circles represent Example 3A, white squares represent Example 3B, and black circles represent Example 3C.

[0070] 6, it was confirmed that Example 3B produced a lower amount of NOx compared to Examples 3A and 3C, regardless of the hydrogen co-firing ratio. This result shows that when the aperture F of convergent port 134 of restrictor 130 is smaller than the outer diameter of flame stabilizer 142, NOx in the exhaust gas can be reduced even when either or both of hydrogen and city gas, which have different flame temperatures, are burned, compared to when the aperture F is equal to or greater than the outer diameter E of flame stabilizer 142.

[0071] [Fourth Example] In order to examine the axial length L of the flame-stabilizing channel 122, burners of Examples 4A to 4C were produced as the fourth example, and the amounts of NOx produced were measured.

[0072] In Example 4A, the axial length L of the flame holding channel 122 was set to 0.6 times the smallest diameter D of the flame holding channel 122. In Example 4B, the axial length L of the flame holding channel 122 was set to 1.5 times the smallest diameter D of the flame holding channel 122. In Example 4C, the axial length L of the flame holding channel 122 was set to 0.25 times the smallest diameter D of the flame holding channel 122.

[0073] Figure 7 is a graph showing the amount of NOx generated in Example 4. In Figure 7, the vertical axis represents the dimensionless amount of NOx, and the horizontal axis represents the hydrogen co-firing ratio [%] relative to the combined calorific value of city gas and hydrogen. In Figure 7, white circles represent Example 4A, and black circles represent Example 4B.

[0074] As shown in FIG. 7, it was confirmed that Example 4A produced a lower amount of NOx than Example 4B, regardless of the hydrogen co-firing ratio.

[0075] Furthermore, in Example 4C, it was confirmed that ignition was not possible with 100% city gas (with a hydrogen co-firing ratio of 0%). From this result, it was found that by setting the axial length L of the flame stabilization channel 122 to at least half the minimum diameter D of the flame stabilization channel 122, it is possible to ensure the ignition of the fuel gas even when city gas, which has a lower combustion speed than hydrogen, is used as the fuel gas.

[0076] [Fifth Example] As a fifth example, a numerical analysis model of the burner of Example 5A and the burner of Example 5B was created, and numerical calculations were used to visualize the gas flow in the flame-stabilizing channel 122 when city gas or hydrogen was burned.

[0077] In the burner of Example 5A, the tip of fuel injection nozzle 160 of Example 2B is retracted to the opposite side of convergent port 134 of orifice 130 with flame stabilizing plate 142 as the reference, as in Example 1C. In the burner of Example 5A, the tip of fuel injection nozzle 160 (fuel injection ports 162a, 162b) is separated from through-hole 142b of flame stabilizing plate 142. In addition, flame stabilizing tube 120 of the burner of Example 5A has a tapered section whose inner diameter gradually increases from the end continuing to reduced diameter section 110a toward the tip, and a main body section whose inner diameter is constant from the tapered section to the tip, and orifice 130 is provided at the tip of the main body section.

[0078] The burner of Example 5B is identical to burner 100 described above.

[0079] Fig. 8 is a diagram showing the simulation results of Example 5A. Fig. 9 is a diagram showing the simulation results of Example 5B. As shown in Fig. 8, it was confirmed that, in the burner of Example 5A, a circulating flow of air was formed in the flame stabilization flow path 122, whether town gas or hydrogen was burned.

[0080] As shown in FIG. 9, it was confirmed that a circulating air flow was formed in the flame-stabilizing flow passage 122 in the burner of Example 5B, whether burning city gas or hydrogen. It was also confirmed that the contact area between the fuel gas injected from the fuel injection nozzle 160 and the formed circulating flow was smaller in the burner of Example 5B than in the burner of Example 5A. It was also confirmed that the amount of NOx was lower in the burner of Example 5B than in the burner of Example 5A. From the above, it was confirmed that the circulating flow formed in the flame-stabilizing flow passage 122 of the burner of Example 5B does not significantly affect the flow of the fuel gas injected from the fuel injection nozzle 160 and has a stronger vortex than the burner of Example 5A. It was confirmed that this is a more suitable mode for slow combustion, whether burning city gas or hydrogen.

[0081] While the preferred embodiments of the present invention have been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to such embodiments. It is clear that those skilled in the art can conceive of various modifications and alterations within the scope of the claims, and it is understood that such modifications and alterations also fall within the technical scope of the present invention.

[0082] For example, in the above embodiment, the diameter of the flame holding channel 122 is constant along the axial direction. However, the diameter of the flame holding channel 122 does not have to be constant along the axial direction as long as a circulating flow can be formed in the flame holding channel 122, in which the flow heading toward the furnace 10 along the inner circumferential surface of the flame holding tube 120 becomes a flow heading toward the flame holding plate 142 via the orifice 130. The diameter of the flame holding channel 122 may, for example, gradually increase or decrease from the reduced diameter portion 110a toward the tip (internal space 20 of the furnace 10).

[0083] In the above embodiment, the case where the fuel injection port 162 faces the convergent port 134 has been exemplified. However, the fuel injection port 162 does not have to face the convergent port 134. The fuel injection port 162 may be configured to inject the fuel gas in a direction intersecting the injection direction of the oxygen-containing gas injection port 150, for example, as in Example 2B above.

[0084] Furthermore, in the above embodiment, the case where fuel injection nozzle 160 penetrates flame stabilizing plate 142 has been exemplified. However, fuel injection nozzle 160 does not have to penetrate flame stabilizing plate 142. For example, fuel injection nozzle 160 may be retracted on the opposite side of convergence port 134 with flame stabilizing plate 142 as the reference, as in Example 1C above.

[0085] In the above embodiment, the outer peripheral surface of the flame stabilizer 142 is spaced apart from the inner peripheral surface of the flame stabilizer tube 120, and the gap formed between the outer peripheral surface of the flame stabilizer 142 and the inner peripheral surface of the flame stabilizer tube 120 includes the oxygen-containing gas injection port 150. However, the outer peripheral surface of the flame stabilizer 142 does not need to be spaced apart from the inner peripheral surface of the flame stabilizer tube 120 as long as a circulating air flow can be formed within the flame stabilizer channel 122 and the fuel gas and air are not mixed more than necessary. In this case, the burner 100 may be provided with an oxygen nozzle having an oxygen-containing gas injection port 150 that opens into the flame stabilizer channel 122 and is spaced apart from the fuel injection port 162 and faces the interior space 20 of the furnace 10. For example, the oxygen nozzle may be provided so that multiple oxygen-containing gas injection ports 150 are arranged concentrically with the fuel injection port 162.

[0086] In the above embodiment, the axial length L of the flame holding channel 122 is 1 / 2 to 1.5 times the smallest diameter D of the flame holding channel 122. However, the axial length L of the flame holding channel 122 may be longer than 1.5 times.

[0087] In the above embodiment, the diameter F of the converging port 134 is smaller than the outer diameter E of the flame stabilizing plate 142. However, there is no limitation on the diameter F of the converging port 134 as long as a circulating flow of air can be formed within the flame stabilizing channel 122. For example, the diameter F of the converging port 134 may be equal to or larger than the outer diameter E of the flame stabilizing plate 142.

[0088] In the above embodiment, the burner 100 is provided with the flame stabilizing tube 120. However, the burner 100 need not necessarily be provided with the flame stabilizing tube 120 as long as it is provided with the flame stabilizing channel 122 that communicates with the internal space 20 of the furnace 10. For example, the flame stabilizing channel 122 may be formed inside the refractory wall 12 of the furnace 10.

[0089] In the above embodiment, the flame stabilizer 140 includes a flame stabilizer plate 142 having a flat surface 142a facing the convergence port 134. However, the flame stabilizer 140 does not have to have a flat surface 142a like the flame stabilizer plate 142, and various other shapes can be adopted as long as it can supply combustion air to a portion of the fuel gas in the flame-stabilizing channel 122 and form a circulating air flow within the flame-stabilizing channel 122. For example, the flame stabilizer 140 may include a tube whose inner diameter gradually increases or decreases toward the interior space 20 of the furnace 10. In any case, the flame stabilizer 140 may be provided between the fuel injection port 162 and the oxygen-containing gas injection port 150.

[0090] In the above embodiment, the throttle 130 is provided at the tip of the flame holding channel 122. However, the throttle 130 may be provided closer to the internal space 20 of the furnace 10 than the fuel injection port 162, the oxygen-containing gas injection port 150, and the flame stabilizer 140. The location of the throttle 130 is not limited as long as it can form a circulating flow of air within the flame holding channel 122. For example, the throttle 130 may be provided within the flame holding channel 122.

[0091] Furthermore, in the above embodiment, an example was given in which the fuel injection port 162 opens substantially at the center of the flame holding passage 122, and the oxygen-containing gas injection port 150 opens around the fuel injection port 162. However, it is sufficient that the fuel injection port 162 and the oxygen-containing gas injection port 150 open to the flame holding passage 122 and are spaced apart from each other. For example, the oxygen-containing gas injection port 150 may open substantially at the center of the flame holding passage 122, and the fuel injection ports 162 may open around the oxygen-containing gas injection port 150. For example, in the above burner 100, the oxygen-containing gas supply unit 180 may supply air to the fuel injection nozzle 160, and the fuel gas supply unit 170 may supply fuel gas to the outer tube 110.

[0092] In the above embodiment, the outer tube 110 includes the reduced diameter portion 110a, the large diameter portion 110b, the expanded diameter portion 110c, and the base end portion 110d. However, the shape of the outer tube 110 is not limited. [Explanation of symbols]

[0093] 10 furnace 20 Interior Space 100 Burner 120 Flame holding tube 122 Flame holding flow path 130 aperture 134 Convergence Port 140 Flame holder 142 Flame holding plate 142a flat surface 150 Oxygen-containing gas nozzle 160 fuel injection nozzle 162 Fuel injection port 162a fuel injection port 162b Fuel injection port

Claims

1. a flame-holding channel communicating with the interior space of the furnace; a fuel injection port that opens into the flame-stabilizing flow path and faces an internal space of the furnace; an oxygen-containing gas injection port that opens into the flame-stabilizing flow path and is spaced apart from the fuel injection port and directed toward an internal space of the furnace; a flame stabilizer provided between the fuel injection port and the oxygen-containing gas injection port; a throttle provided closer to the furnace interior space than the fuel injection port, the oxygen-containing gas injection port, and the flame stabilizer, the throttle having a convergent port smaller than a flow path cross-sectional area of ​​the flame-stabilizing flow path; A burner comprising:

2. the flame holder includes a flame holder plate having a flat surface facing the convergence port, The burner according to claim 1 , wherein the diameter of the convergence port is smaller than the outer diameter of the flame stabilizing plate.

3. 3. The burner according to claim 2, wherein the diameter of said converging port is equal to or smaller than 4 / 5 of the outer diameter of said flame stabilizing plate.

4. The axial length of the flame-holding channel is 3. The burner according to claim 1, wherein the diameter of the flame-holding passage is between 1 / 2 and 1.5 times the smallest diameter of the flame-holding passages.

5. a flame stabilizing tube that forms the flame stabilizing flow path; The outer peripheral surface of the flame stabilizing plate is spaced apart from the inner peripheral surface of the flame stabilizing tube, 4. The burner according to claim 2, wherein the oxygen-containing gas injection port is included in a gap formed between the outer peripheral surface of the flame stabilizing plate and the inner peripheral surface of the flame stabilizing tube.

6. the flame holder includes a flame holder plate having a flat surface facing the convergence port, 3. The burner according to claim 1, further comprising a fuel injection nozzle having the fuel injection port and penetrating the flame stabilizing plate.

7. 3. The burner according to claim 1, wherein the fuel injection port faces the convergence port.

8. 3. The burner according to claim 1, wherein the flame-holding channel has a constant diameter in the axial direction.

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