Burner

Abstract

To reduce NOx in exhaust gas.SOLUTION: A burner 100 includes: a fuel injection part 110 including one or a plurality of mixed gas injection ports 114b (fuel injection ports) provided toward an inner space of a furnace; a first injection part 130 including one or a plurality of first large injection ports 132b and first small injection ports 134b (first injection ports) that are separated from the mixed gas injection ports 114b and provided toward the inner space of the furnace; a second injection part 140 including one or a plurality of second large injection ports 142b and second small injection ports 144b (second injection ports) that are separated from the mixed gas injection ports 114b and provided toward the inner space of the furnace; a fuel supply part 120 supplying fuel gas including at least ammonia to the fuel injection part 110; and an oxidant supply part 150 supplying oxidant gas to the first injection part 130 and the second injection part 140. A flow rate of the oxidant gas injected by the first injection part 130 is different from that of the oxidant gas injected by the second injection part 140.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] In recent years, there has been a demand for reducing CO2 (carbon dioxide) emissions to prevent global warming, and for this reason, attention has been focused on technology that burns ammonia in addition to fossil fuels (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2020-112280 Summary of the Invention [Problem to be solved by the invention]

[0004] When ammonia is burned, there is a problem that the concentration of nitrogen oxides in the exhaust gas increases compared to when only fossil fuels are burned.

[0005] In view of the above problems, the present invention has an object to provide a burner that can reduce nitrogen oxides in exhaust gas. [Means for solving the problem]

[0006] In order to solve the above problems, the burner of the present invention comprises a fuel injection section including one or more fuel injection ports provided facing the internal space of the furnace, a first injection section including the fuel injection ports and one or more first injection ports provided facing the internal space of the isolated furnace, a second injection section including the fuel injection ports and one or more second injection ports provided facing the internal space of the isolated furnace, a fuel supply section that supplies a fuel gas containing at least ammonia to the fuel injection section, and an oxidizer supply section that supplies an oxidizer gas to the first injection section and the second injection section, a switching control unit that alternates between a first state in which the flow rate of the oxidant gas injected by the first injector is larger than the flow rate of the oxidant gas injected by the second injector and a second state in which the flow rate of the oxidant gas injected by the first injector is smaller than the flow rate of the oxidant gas injected by the second injector; Equipped with The first injection port has a first large injection port and a first small injection port having a smaller diameter than the first large injection port, and the second injection port has a second large injection port and a second small injection port having a smaller diameter than the second large injection port, and the switching control unit, in a first state, causes oxidant gas to be injected from the first large injection port and the second small injection port and stops injection of oxidant gas from the first small injection port and the second large injection port, and, in a second state, stops injection of oxidant gas from the first large injection port and the second small injection port and causes oxidant gas to be injected from the first small injection port and the second large injection port. .

[0009] In addition, the flow rate of the oxidant gas injected by one of the first injector and the second injector may be 2.3 times or more and less than 6.3 times the flow rate of the oxidant gas injected by the other of the first injector and the second injector.

[0010] Also, fuel injection Center of the nozzle, center of the first large nozzle, and center of the first small nozzle and the imaginary line connecting the fuel injection Center of the nozzle, center of the second large nozzle, and center of the second small nozzle The angle formed with the imaginary line connecting the above points may be greater than or equal to 90° and less than or equal to 270°. [Effects of the Invention]

[0011] According to the present invention, it is possible to reduce nitrogen oxides in exhaust gas. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a diagram illustrating a burner according to an embodiment of the present invention. FIG. [Figure 2] This is a view of the mixed gas injection nozzle of the fuel injection section, the first large injection nozzle and first small injection nozzle of the first injection section, the second large injection nozzle and second small injection nozzle of the second injection section, as seen from the internal space side of the furnace. [Figure 3] FIG. 4 is a diagram illustrating the flow of secondary air in a first state. [Figure 4] FIG. 10 is a diagram illustrating the flow of secondary air in a second state. [Figure 5] FIG. 4 is a diagram showing the relationship between the concentration of NOx in exhaust gas and the flow rate ratio. [Figure 6] FIG. 10 is a diagram illustrating a burner according to a first modified example. [Figure 7] FIG. 10 is a diagram illustrating a first injector and a second injector according to a second modified example. [Figure 8] 10A and 10B are diagrams illustrating a first injector and a second injector according to a third modified example. DETAILED DESCRIPTION OF THE INVENTION

[0013] 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.

[0014] [Burna 100] FIG. 1 is a diagram illustrating a burner 100 according to this embodiment. As shown in FIG. 1, the burner 100 is provided on a furnace wall 12 that constitutes a furnace 10 (for example, a furnace that constitutes a boiler). The burner 100 burns a fuel gas that contains at least ammonia. The fuel gas may contain only ammonia, or may contain hydrogen, hydrocarbons, etc. in addition to ammonia. The hydrocarbons include methane, ethane, propane, butane, etc.

[0015] The burner 100 includes a fuel injection unit 110 , a fuel supply unit 120 , a first injection unit 130 , a second injection unit 140 , an oxidant supply unit 150 , and a central control unit 160 .

[0016] The fuel injection unit 110 is provided facing the internal space of the furnace 10. The fuel injection unit 110 injects a fuel gas and an oxidizing gas. Here, the oxidizing gas is air as an example. In this embodiment, the fuel injection unit 110 has a fuel supply nozzle 112 and a mixed gas injection nozzle 114.

[0017] The fuel supply nozzle 112 is a nozzle that supplies fuel gas. The fuel supply nozzle 112 includes a main body 112a, a fuel supply pipe 112b, and a fuel supply port 112c. The main body 112a is a cylindrical pipe. The central axis of the main body 112a intersects with the furnace wall 12 (here, approximately perpendicularly).

[0018] A fuel supply pipe 112b is connected to the rear of the main body 112a (the side of the main body 112a opposite to the furnace wall 12 side (left side in FIG. 1, hereinafter referred to as the "rear end")). An opening, a fuel supply port 112c, is formed at the front end of the main body 112a (the furnace wall 12 side of the main body 112a (right side in FIG. 1), hereinafter referred to as the "front end"). The fuel supply port 112c faces the interior space of the furnace 10.

[0019] The mixed gas injection nozzle 114 is a nozzle that injects a mixed gas containing fuel gas and air (primary air). The mixed gas injection nozzle 114 has a main body 114a and a mixed gas injection port 114b (fuel injection port). The main body 114a is a cylindrical tubular body. The main body 114a is arranged coaxially with the main body 112a of the fuel supply nozzle 112 so as to surround the main body 112a. In other words, the main body 112a of the fuel supply nozzle 112 and the main body 114a of the mixed gas injection nozzle 114 form a double cylindrical structure. FIG. 1 shows an example in which a tip portion 114c of the main body 114a located on the furnace wall 12 side (the right side in FIG. 1, hereinafter referred to as the "tip") has a shape in which the diameter gradually decreases toward the tip, but the shape of the mixed gas injection nozzle 114 is not limited to this.

[0020] An oxidizing agent supply pipe 154, which will be described later, is connected to the rear part of the main body 114a (the opposite side of the main body 114a to the furnace wall 12 side (the left side in FIG. 1, hereinafter referred to as the "rear end")).

[0021] Furthermore, a mixed gas injection port 114b, which is an opening, is formed at the tip of the main body 114a. The mixed gas injection port 114b faces the internal space of the furnace 10.

[0022] In this embodiment, the fuel supply port 112c of the fuel supply nozzle 112 is provided so as to be located inside the main body 114a of the mixed gas injection nozzle 114. In other words, the mixed gas injection port 114b of the mixed gas injection nozzle 114 is provided closer to the internal space of the furnace 10 than the fuel supply port 112c of the fuel supply nozzle 112.

[0023] The fuel supply unit 120 supplies fuel gas to the fuel injection unit 110. The fuel gas is supplied from the fuel supply unit 120 into the main body 112a via the fuel supply pipe 112b. The fuel gas supplied into the main body 112a flows through the space within the main body 112a. The fuel gas that has passed through the main body 112a is injected from the fuel supply port 112c toward the space formed within the tip end 114c of the main body 114a.

[0024] In this embodiment, primary air is supplied into the main body 114a. As described above, the oxidant supply pipe 154 is connected to the main body 114a. The primary air supplied into the main body 114a flows through the space within the main body 114a. The primary air reaches the tip end 114c of the main body 114a and is mixed with fuel gas injected from the fuel supply port 112c in the space within the tip end 114c. The mixed gas containing the fuel gas and the primary air is injected into the internal space of the furnace 10 from the mixed gas injection port 114b.

[0025] In this way, the mixed gas injected from the mixed gas injection port 114b is ignited by an ignition device (not shown), and a flame is formed in the internal space of the furnace 10.

[0026] The first injector 130 and the second injector 140 supply air (secondary air) to the flame formed by the fuel injector 110 from the radially outer side.

[0027] The first injection section 130 includes a first injection nozzle 132, an on-off valve 132c, a first injection nozzle 134, and an on-off valve 134c. The first injection nozzles 132 and 134 are nozzles that inject secondary air.

[0028] The first injection nozzle 132 includes a main body 132a and a first large injection port 132b (first injection port). The main body 132a is a cylindrical tubular body. The central axis of the main body 132a intersects with the furnace wall 12 (here, approximately perpendicularly).

[0029] An oxidizer supply pipe 154 is connected to the rear of the main body 132a (the side of the main body 132a opposite to the furnace wall 12 side (left side in FIG. 1, hereinafter referred to as the "rear end")). In addition, a first large injection port 132b, which is an opening, is formed at the front end of the main body 132a (the furnace wall 12 side of the main body 132a (right side in FIG. 1), hereinafter referred to as the "front end"). The first large injection port 132b faces the interior space of the furnace 10.

[0030] The on-off valve 132c is provided in the main body 132a. The on-off valve 132c opens and closes a flow path formed in the main body 132a. The on-off valve 132c is opened and closed by a switching control unit 162, which will be described later.

[0031] The first injection nozzle 134 includes a main body 134a and a first small injection port 134b (first injection port). The main body 134a is a cylindrical tubular body. The central axis of the main body 134a intersects (here, approximately perpendicular to) the furnace wall 12. In this embodiment, the main body 134a has a smaller diameter than the main body 132a.

[0032] An oxidizer supply pipe 154 is connected to the rear of the main body 134a (the side of the main body 134a opposite to the furnace wall 12 side (the left side in FIG. 1, hereinafter referred to as the "rear end")). In addition, a first small jet orifice 134b, which is an opening, is formed at the front end of the main body 134a (the furnace wall 12 side of the main body 134a (the right side in FIG. 1), hereinafter referred to as the "front end"). The first small jet orifice 134b faces the interior space of the furnace 10. The first small jet orifice 134b has a smaller diameter than the first large jet orifice 132b.

[0033] The on-off valve 134c is provided in the main body 134a. The on-off valve 134c opens and closes a flow path formed in the main body 134a. The on-off valve 134c is opened and closed by the switching control unit 162.

[0034] The second injection section 140 includes a second injection nozzle 142, an on-off valve 142c, a second injection nozzle 144, and an on-off valve 144c. The second injection nozzles 142, 144 are nozzles that inject secondary air.

[0035] The second injection nozzle 142 includes a main body 142a and a second large injection port 142b (second injection port). The main body 142a is a cylindrical tubular body. The central axis of the main body 142a intersects (here, approximately perpendicular to) the furnace wall 12. The pipe diameter of the main body 142a is substantially equal to the pipe diameter of the main body 132a of the first injection section 130.

[0036] An oxidizer supply pipe 154 is connected to the rear of the main body 142a (the side of the main body 142a opposite to the furnace wall 12 side (the left side in FIG. 1, hereinafter referred to as the "rear end")). In addition, a second large jet orifice 142b, which is an opening, is formed at the front end of the main body 142a (the furnace wall 12 side of the main body 142a (the right side in FIG. 1), hereinafter referred to as the "front end"). The second large jet orifice 142b faces the interior space of the furnace 10. The diameter of the second large jet orifice 142b is substantially equal to the diameter of the first large jet orifice 132b.

[0037] The on-off valve 142c is provided in the main body 142a. The on-off valve 142c opens and closes a flow path formed in the main body 142a. The on-off valve 142c is opened and closed by the switching control unit 162.

[0038] The second injection nozzle 144 includes a main body 144a and a second small injection port 144b (second injection port). The main body 144a is a cylindrical tubular body. The central axis of the main body 144a intersects (here, approximately perpendicular to) the furnace wall 12. In this embodiment, the main body 144a has a smaller diameter than the main body 142a. The pipe diameter of the main body 144a is substantially equal to the pipe diameter of the main body 134a of the first injection section 130.

[0039] An oxidizer supply pipe 154 is connected to the rear of the main body 144a (the side of the main body 144a opposite to the furnace wall 12 side (the left side in FIG. 1, hereinafter referred to as the "rear end")). In addition, a second small jet orifice 144b, which is an opening, is formed at the front end of the main body 144a (the furnace wall 12 side of the main body 144a (the right side in FIG. 1), hereinafter referred to as the "front end"). The second small jet orifice 144b faces the interior space of the furnace 10. The second small jet orifice 144b has a smaller diameter than the second large jet orifice 142b. The diameter of the second small jet orifice 144b is substantially equal to the diameter of the first small jet orifice 134b.

[0040] The on-off valve 144c is provided in the main body 144a. The on-off valve 144c opens and closes a flow path formed in the main body 144a. The on-off valve 144c is opened and closed by the switching control unit 162.

[0041] The first large injection nozzle 132b, the first small injection nozzle 134b, the second large injection nozzle 142b, and the second small injection nozzle 144b are provided on approximately the same plane as the mixed gas injection nozzle 114b of the fuel injection unit 110. In other words, the axial position of the tip of the main body 132a, 134a, 142a, 144a approximately coincides with the axial position of the mixed gas injection nozzle 114b of the fuel injection unit 110.

[0042] Figure 2 is a view of the mixed gas injection nozzle 114b of the fuel injection section 110, the first large injection nozzle 132b, the first small injection nozzle 134b of the first injection section 130, the second large injection nozzle 142b, and the second small injection nozzle 144b of the second injection section 140, viewed from the internal space side of the furnace 10.

[0043] As shown in FIG. 2, the center of the mixed gas injection port 114b of the fuel injection unit 110 is separated by a distance Lm from the center of the first large injection port 132b of the first injection unit 130. Similarly, the center of the mixed gas injection port 114b of the fuel injection unit 110 is separated by a distance Lm from the center of the second small injection port 144b of the second injection unit 140. The distance Lm is, for example, 1.85 times or more and less than 6.0 times the diameter D of the mixed gas injection port 114b. By setting the distance Lm to 1.85 times or more the diameter D, it is possible to reduce NOx in the exhaust gas. On the other hand, if the distance Lm is 6.0 times or more the diameter D, unburned ammonia will be contained in the exhaust gas. Therefore, by setting the distance Lm to less than 6.0 times the diameter D, it is possible to avoid the generation of unburned ammonia. In other words, by setting the distance Lm to be 1.85 times or more and less than 6.0 times the diameter D, it is possible to reduce the NOx concentration in the exhaust gas and prevent unburned ammonia from being contained in the exhaust gas.

[0044] In the first injection section 130, the first large injection nozzle 132b and the first small injection nozzle 134b are separated by a distance Ln. Similarly, in the second injection section 140, the second large injection nozzle 142b and the second small injection nozzle 144b are separated by a distance Ln. The distance Ln is as close to zero as possible.

[0045] Also, as shown in Figure 2, the center of the mixed gas injection port 114b of the fuel injection section 110, the center of the first large injection port 132b of the first injection section 130, the center of the first small injection port 134b, the center of the second large injection port 142b of the second injection section 140, and the center of the second small injection port 144b are located on the imaginary straight line V.

[0046] Returning to FIG. 1, the oxidizing agent supply unit 150 supplies air to the first injection unit 130 (first injection nozzles 132, 134), the second injection unit 140 (second injection nozzles 142, 144), and the mixed gas injection nozzle 114.

[0047] In this embodiment, the oxidizing agent supply unit 150 includes an oxidizing agent supply system 152 and an oxidizing agent supply pipe 154. Air is supplied from the oxidizing agent supply system 152 to the oxidizing agent supply pipe 154.

[0048] The central control unit 160 is composed of a semiconductor integrated circuit including a CPU (Central Processing Unit). The central control unit 160 reads programs and parameters for operating the CPU from the ROM. The central control unit 160 manages and controls the entire burner 100 in cooperation with RAM as a work area and other electronic circuits.

[0049] In this embodiment, the central control unit 160 functions as a switching control unit 162. The switching control unit 162 opens and closes the on-off valves 132c, 134c, 142c, and 144c to alternate between a first state and a second state at predetermined time intervals. In the first state, the flow rate of the secondary air injected by the first injection unit 130 is greater than the flow rate of the secondary air injected by the second injection unit 140. In the second state, the flow rate of the secondary air injected by the first injection unit 130 is smaller than the flow rate of the secondary air injected by the second injection unit 140. The predetermined time is determined based on the volume and dimensions of the furnace 10 and the material properties (e.g., specific heat and thermal conductivity) of the firing material. The predetermined time is, for example, 15 seconds to 2 minutes.

[0050] Specifically, the switching control unit 162 opens the on-off valves 132c and 144c and closes the on-off valves 134c and 142c to enter the first state, which causes secondary air to be injected from the first large injection nozzle 132b and the second small injection nozzle 144b, and stops injection of secondary air from the first small injection nozzle 134b and the second large injection nozzle 142b.

[0051] Furthermore, the switching control unit 162 closes the on-off valves 132c and 144c and opens the on-off valves 134c and 142c to enter the second state, which stops the injection of secondary air from the first large injection nozzle 132b and the second small injection nozzle 144b and starts the injection of secondary air from the first small injection nozzle 134b and the second large injection nozzle 142b.

[0052] That is, the switching control unit 162 exclusively opens and closes the on-off valves 132c and 134c, and exclusively opens and closes the on-off valves 142c and 144c. Also, the switching control unit 162 exclusively opens and closes the on-off valves 132c and 142c, and exclusively opens and closes the on-off valves 134c and 144c.

[0053] Fig. 3 is a diagram illustrating the flow of secondary air in the first state. In Fig. 3, the closed valve state is indicated by solid black.

[0054] 3, in the first state, secondary air is injected into the internal space of the furnace 10 from the first large injection port 132b and the second small injection port 144b. As described above, the first large injection port 132b has a larger diameter than the second small injection port 144b. Therefore, the flow rate of secondary air injected from the first large injection port 132b is greater than the flow rate of secondary air injected from the second small injection port 144b.

[0055] As a result, a circulating flow (swirl flow) of secondary air is formed in the internal space of the furnace 10 in a clockwise direction in FIG. 3. This allows the burner 100 to promote a denitrification reaction in the exhaust gas generated by the combustion of the fuel gas. Therefore, the burner 100 can reduce NOx (nitrogen oxides) in the exhaust gas.

[0056] Fig. 4 is a diagram illustrating the flow of secondary air in the second state. In Fig. 4, the closed valve state is indicated by solid black.

[0057] 4, in the second state, secondary air is injected into the internal space of the furnace 10 from the second large injection port 142b and the first small injection port 134b. As described above, the second large injection port 142b has a larger diameter than the first small injection port 134b. Therefore, the flow rate of secondary air injected from the second large injection port 142b is greater than the flow rate of secondary air injected from the first small injection port 134b.

[0058] As a result, a counterclockwise circulating flow of secondary air is formed in the internal space of the furnace 10 in FIG. 4. As a result, similar to the first state, the burner 100 can promote the denitrification reaction in the exhaust gas generated by the combustion of the fuel gas. Therefore, the burner 100 can reduce NOx in the exhaust gas.

[0059] Furthermore, by alternately switching between the first state and the second state by the switching control unit 162, it is possible to prevent the temperature in the furnace 10 from becoming uneven. Therefore, the burner 100 can make the temperature in the furnace 10 uniform.

[0060] [Ratio of primary air to secondary air flow rate] Next, the ratio between the amount of primary air injected from the fuel injection section 110 and the amount of secondary air injected from the first injection section 130 and the second injection section 140 will be described.

[0061] The fuel injection unit 110, the first injection unit 130, and the second injection unit 140 inject a target amount of air in total. The target amount of air is a predetermined amount of air that is equal to or greater than the theoretical amount of air for the fuel gas supplied to the fuel injection unit 110 (fuel supply nozzle 112) by the fuel supply unit 120. The theoretical amount of air is the minimum amount of air required for complete combustion of the fuel gas. The target amount of air is, for example, 1.1 to 1.2 times the theoretical amount of air.

[0062] Furthermore, the amount of primary air in the mixed gas injected by the fuel injection unit 110 is between 1 / 3 and 2 / 3 of the target air amount, and preferably 1 / 2. This enables the fuel injection unit 110 to reduce NOx without reducing the ignition ability of the fuel gas.

[0063] By setting the amount of primary air in the mixed gas injected by the fuel injection unit 110 to be less than the target air amount, even if the fuel gas (ammonia) in the mixed gas injected from the mixed gas injection port 114b into the internal space of the furnace 10 is burned with primary air, unburned ammonia remains in the internal space of the furnace 10. Therefore, in the internal space of the furnace 10, NOx generated by the ammonia burned with primary air can be reduced (denitrified) by the unburned ammonia. Therefore, the burner 100 can reduce NOx in the exhaust gas generated in the internal space of the furnace 10.

[0064] The first injector 130 and the second injector 140 then inject secondary air in an amount equal to the difference between the amount of primary air contained in the mixed gas and the target air amount, thereby enabling the burner 100 to completely combust the unburned fuel gas with the secondary air.

[0065] The diameter of the mixed gas injection nozzle 114b of the fuel injection section 110, the diameter of the first large injection nozzle 132b of the first injection section 130, the diameter of the first small injection nozzle 134b, the diameter of the second large injection nozzle 142b of the second injection section 140, and the diameter of the second small injection nozzle 144b have a dimensional relationship such that the primary air is at least 1 / 3 and not more than 2 / 3 (preferably 1 / 2) of the target air volume, and the secondary air is the difference between the volume of the primary air and the target air volume.

[0066] [Flow rate ratio of mixed gas to secondary air] Next, the relationship between the flow velocity of the mixed gas injected from the mixed gas injection port 114b and the flow velocity of the secondary air injected from the first injection part 130 and the second injection part 140 will be described.

[0067] The flow velocity ratio a / b between the flow velocity a of the mixed gas injected from the mixed gas injection port 114b and the flow velocity b of the secondary air injected from the first injection part 130 and the second injection part 140 is 0.05 or more. This makes it possible to reduce the amount of NOx contained in the exhaust gas discharged from the flue (chimney) of the furnace 10.

[0068] The diameter of the mixed gas injection port 114b of the fuel injection section 110, the diameter of the first large injection port 132b of the first injection section 130, the diameter of the first small injection port 134b, the diameter of the second large injection port 142b of the second injection section 140, and the diameter of the second small injection port 144b have a dimensional relationship such that the flow velocity ratio a / b is 0.05 or more.

[0069] [Secondary air flow rate ratio] Next, the ratio between the flow rate of the secondary air injected from the first injector 130 and the flow rate of the secondary air injected from the second injector 140 will be described.

[0070] In the first state, the flow rate of the secondary air injected from the first injection section 130 (first large injection port 132b) is 2.3 to less than 6.3 times, and preferably 3.8 to less than 6.3 times, the flow rate of the secondary air injected from the second injection section 140 (second small injection port 144b). Similarly, in the second state, the flow rate of the secondary air injected from the second injection section 140 (second large injection port 142b) is 2.3 to less than 6.3 times, and preferably 3.8 to less than 6.3 times, the flow rate of the secondary air injected from the first injection section 130 (first small injection port 134b).

[0071] In other words, the flow rate of the secondary air injected by one of the first injection section 130 and the second injection section 140 is at least 2.3 times and less than 6.3 times the flow rate of the secondary air injected by the other of the first injection section 130 and the second injection section 140, and preferably at least 3.8 times and less than 6.3 times.

[0072] Fig. 5 is a diagram showing the relationship between the concentration of NOx in exhaust gas and the flow rate ratio. In Fig. 5, the vertical axis represents the converted NOx concentration [ppm], and the horizontal axis represents the flow rate ratio of the secondary air between the first injection section 130 and the second injection section 140. The converted NOx concentration is a value calculated using the following formula (1). Equivalent NOx concentration = measured NOx concentration × (21 - equivalent O2 concentration) / (21 - measured O2 concentration) ... Formula (1) In this embodiment, the converted O2 concentration is set to 11 to calculate the converted NOx concentration.

[0073] As shown in FIG. 5, when the flow rate ratio of the secondary air between the first injector 130 and the second injector 140 was 1 (for example, 41 [L / min]:41 [L / min]), the converted NOx concentration was 169 ppm.

[0074] On the other hand, it was confirmed that the converted NOx concentration decreases as the flow rate ratio of the secondary air between the first injection section 130 and the second injection section 140 exceeds 1. Specifically, when the flow rate ratio of the secondary air between the first injection section 130 and the second injection section 140 is 2.3 (e.g., 57 [L / min]:25 [L / min]), the converted NOx concentration was 164 ppm. Furthermore, when the flow rate ratio of the secondary air between the first injection section 130 and the second injection section 140 is 3.8 (e.g., 65 [L / min]:17 [L / min]), the converted NOx concentration was 144 ppm. When the flow rate ratio of the secondary air between the first injection section 130 and the second injection section 140 is 5.3 (e.g., 69 [L / min]:13 [L / min]), the converted NOx concentration was 142 ppm.

[0075] From the above results, it was confirmed that the NOx concentration in the exhaust gas can be reduced by making the flow rate of the secondary air injected by one of the first injection section 130 and the second injection section 140 at least 2.3 times the flow rate of the secondary air injected by the other of the first injection section 130 and the second injection section 140.

[0076] Furthermore, if the flow rate of the secondary air injected by one of the first injector 130 and the second injector 140 is 6.3 times or more the flow rate of the secondary air injected by the other of the first injector 130 and the second injector 140, unburned ammonia and nitrous oxide (N2O) will be contained in the exhaust gas. The global warming potential of nitrous oxide is approximately 310 times that of carbon dioxide, and it is not desirable to exhaust it to the outside.

[0077] Specifically, when the ratio is less than 6.3, the amount of unburned ammonia is less than 1 ppm (detection limit) and the amount of nitrous oxide is less than 0.1 ppm (detection limit). On the other hand, when the ratio is 6.3, the amount of unburned ammonia is 5 ppm to 10 ppm and the amount of nitrous oxide is 0.1 ppm. Furthermore, when the ratio is 9, the amount of unburned ammonia is 50 ppm or more and the amount of nitrous oxide is 20 ppm or more.

[0078] Therefore, by setting the flow rate of the secondary air injected by one of the first injection section 130 and the second injection section 140 to less than 6.3 times the flow rate of the secondary air injected by the other of the first injection section 130 and the second injection section 140, it is possible to avoid the situation where unburned ammonia and nitrous oxide are contained in the exhaust gas.

[0079] In other words, by setting the flow rate of the secondary air injected by one of the first injection section 130 and the second injection section 140 to be 2.3 times or more and less than 6.3 times the flow rate of the secondary air injected by the other of the first injection section 130 and the second injection section 140, it is possible to reduce the NOx concentration in the exhaust gas and avoid a situation in which unburned ammonia and nitrous oxide are contained in the exhaust gas.

[0080] The diameter of the first large injection nozzle 132b of the first injection section 130 and the diameter of the second small injection nozzle 144b of the second injection section 140 have a dimensional relationship such that the flow rate of secondary air injected from the first large injection nozzle 132b is 2.3 times or more and less than 6.3 times (preferably, 3.8 times or more and less than 6.3 times) the flow rate of secondary air injected from the second small injection nozzle 144b.

[0081] Similarly, the diameter of the first small injection nozzle 134b of the first injection section 130 and the diameter of the second large injection nozzle 142b of the second injection section 140 have a dimensional relationship such that the flow rate of secondary air injected from the second large injection nozzle 142b is 2.3 times or more and less than 6.3 times (preferably, 3.8 times or more and less than 6.3 times) the flow rate of secondary air injected from the first small injection nozzle 134b.

[0082] In addition, in this embodiment, the first large injection port 132b and the first small injection port 134b of the first injection section 130, and the second large injection port 142b and the second small injection port 144b of the second injection section 140 inject secondary air at substantially the same flow rate.

[0083] As described above, the burner 100 according to this embodiment can reduce the NOx concentration in the exhaust gas.

[0084] [First Modification] Fig. 6 is a diagram illustrating a burner 200 according to a first modified example. As shown in Fig. 6, the burner 200 is similar to the burner 100 described above except that it is equipped with three-way valves 210 and 220 instead of the on-off valves 132c, 134c, 142c, and 144c. Therefore, components that are substantially the same as those of the burner 100 described above are denoted by the same reference numerals and descriptions thereof will be omitted.

[0085] The three-way valve 210 is provided at a connection point of the oxidizing agent supply pipe 154 with the first injection nozzle 132. The three-way valve 210 switches the connection destination of the oxidizing agent supply pipe 154 between the first injection nozzle 132 and the first injection nozzle .

[0086] The three-way valve 220 is provided at a connection point of the oxidizing agent supply pipe 154 with the second injection nozzle 144. The three-way valve 220 switches the connection destination of the oxidizing agent supply pipe 154 between the second injection nozzle 142 and the second injection nozzle 144.

[0087] The three-way valves 210 and 220 are switched by a switching control unit 162 .

[0088] The burner 200 according to the first modification, like the burner 100, can form a circulating flow of secondary air in the internal space of the furnace 10. This allows the burner 200 to promote a denitrification reaction in the exhaust gas generated by the combustion of fuel gas. Therefore, the burner 200 can reduce NOx in the exhaust gas. Furthermore, the switching control unit 162 can alternate between the first state and the second state by switching the three-way valves 210 and 220. This allows the burner 200 to avoid a situation in which the temperature inside the furnace 10 becomes uneven. Therefore, the burner 200 can homogenize the temperature inside the furnace 10.

[0089] [Second Modification, Third Modification] In the first embodiment described above, the burner 100 is exemplified as having one first injection section 130 and one second injection section 140 (one set of first injection nozzles 132, 134, and one set of second injection nozzles 142, 144). However, there is no limitation on the number of first injection sections 130 and second injection sections 140.

[0090] Figure 7 is a diagram illustrating a first injector 130 and a second injector 140 according to a second modified example. As shown in Figure 7, in the second modified example, the first injector 130 has two pairs of first large injection ports 132b and first small injection ports 134b. Furthermore, the second injector 140 has two pairs of second large injection ports 142b and second small injection ports 144b.

[0091] In the second modified example, the angle α formed by the imaginary line V1 connecting the fuel injection section 110 (the center of the mixed gas injection port 114b) and the first injection section 130 (the center of the lower first large injection port 132b and the center of the first small injection port 134b in FIG. 7) and the imaginary line V2 connecting the fuel injection section 110 and the second injection section 140 (the center of the lower second large injection port 142b and the center of the second small injection port 144b in FIG. 7) is 90°. Also, the angle α formed by the imaginary line connecting the centers of the upper first large injection port 132b and the first small injection port 134b in FIG. 7 and the fuel injection section 110 and the imaginary line connecting the centers of the lower second large injection port 142b and the second small injection port 144b in FIG. 7 and the fuel injection section 110 is 180°.

[0092] Figure 8 is a diagram illustrating a first injector 130 and a second injector 140 according to a third modified example. As shown in Figure 8, in the third modified example, the first injector 130 has three pairs of first large injection ports 132b and first small injection ports 134b. The second injector 140 has three pairs of second large injection ports 142b and second small injection ports 144b.

[0093] In the third modified example, the angle α formed by the imaginary line connecting the centers of the upper first large injection nozzle 132b and first small injection nozzle 134b in Fig. 8 and the fuel injection section 110 and the imaginary line connecting the centers of the lower second large injection nozzle 142b and second small injection nozzle 144b in Fig. 8 and the fuel injection section 110 is 180°. Also, the angle α formed by the imaginary line connecting the centers of the central first large injection nozzle 132b and first small injection nozzle 134b in Fig. 8 and the fuel injection section 110 and the imaginary line connecting the centers of the central second large injection nozzle 142b and second small injection nozzle 144b in Fig. 8 and the fuel injection section 110 is 180°. The angle α between an imaginary line connecting the centers of the first large injection nozzle 132b and the first small injection nozzle 134b on the lower side in Figure 8 and the fuel injection section 110 and an imaginary line connecting the centers of the second large injection nozzle 142b and the second small injection nozzle 144b on the upper side in Figure 8 and the fuel injection section 110 is 180°.

[0094] 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.

[0095] For example, in the above-described embodiment, air is used as an example of the oxidant gas. However, the oxidant gas may be any gas as long as it can burn the fuel gas. In addition to air, the oxidant gas may be, for example, oxygen-enriched air or oxygen. When the oxidant gas is other than air, the theoretical air amount becomes the theoretical oxidant amount, and the target air amount becomes the target oxidant amount. The theoretical oxidant amount is the minimum amount of oxidant gas required to completely combust the fuel gas. The target oxidant amount is a predetermined oxidant gas amount that is equal to or greater than the theoretical oxidant amount, for example, 1.1 to 1.2 times the theoretical oxidant amount.

[0096] Furthermore, in the above embodiment, the first large injection port 132b and the first small injection port 134b of the first injection unit 130 and the second large injection port 142b and the second small injection port 144b of the second injection unit 140 are provided on approximately the same plane as the mixed gas injection port 114b of the fuel injection unit 110. However, the first large injection port 132b and the first small injection port 134b of the first injection unit 130 and the second large injection port 142b and the second small injection port 144b of the second injection unit 140 do not have to be provided on approximately the same plane as the mixed gas injection port 114b of the fuel injection unit 110. For example, the first large injection port 132b and the first small injection port 134b of the first injection unit 130 and the second large injection port 142b and the second small injection port 144b of the second injection unit 140 may be provided facing the flame.

[0097] In the above embodiment, the fuel supply port 112c of the fuel supply nozzle 112 is provided so as to be positioned within the main body 114a of the mixed gas injection nozzle 114. However, the fuel supply port 112c of the fuel supply nozzle 112 may be provided on approximately the same plane as the mixed gas injection port 114b of the mixed gas injection nozzle 114, or may protrude from the tip of the main body 114a of the mixed gas injection nozzle 114. In this case, the fuel supply port 112c functions as the fuel injection port, and primary air is injected from the mixed gas injection port 114b, generating mixed gas in the internal space of the furnace 10. In addition, when the mixed gas injection port 114b injects primary air, multiple fuel supply ports 112c and multiple mixed gas injection ports 114b may be provided, or one fuel supply port 112c may be provided and multiple mixed gas injection ports 114b may be provided surrounding the fuel supply port 112c.

[0098] In the above embodiment, the fuel injection unit 110 includes the fuel supply nozzle 112 and the mixed gas injection nozzle 114. However, the fuel injection unit 110 may include a single nozzle through which the mixed gas of fuel gas and oxidant gas flows. In this case, the fuel injection unit 110 includes one or more fuel injection ports for injecting the mixed gas.

[0099] Furthermore, in the above embodiment, an example was given in which the first large injection port 132b of the first injection unit 130 is closer to the mixed gas injection port 114b than the first small injection port 134b. However, the first large injection port 132b may be farther away from the mixed gas injection port 114b than the first small injection port 134b. Similarly, an example was given in which the second small injection port 144b of the second injection unit 140 is closer to the mixed gas injection port 114b than the second large injection port 142b. However, the second small injection port 144b may be farther away from the mixed gas injection port 114b than the second large injection port 142b.

[0100] In the above embodiment, an example has been given in which air is supplied from one oxidant supply unit 150 to the mixed gas injection nozzle 114, the first injection unit 130, and the second injection unit 140. However, the burner 100 may be provided with an oxidant supply unit that supplies air to the mixed gas injection nozzle 114, an oxidant supply unit that supplies air to the first injection unit 130, and an oxidant supply unit that supplies air to the second injection unit 140, all of which are separate units. In addition, the burner 100 may be provided with an oxidant supply unit that supplies air to the mixed gas injection nozzle 114, and an oxidant supply unit that supplies air to the first injection unit 130 and the second injection unit 140, all of which are separate units.

[0101] Furthermore, in the above embodiment, the burner 100 includes the switching control unit 162. However, the burner 100 does not necessarily need to include the switching control unit 162. For example, the burner 100 may include a first injector 130 having a first large injection nozzle 132b but not a first small injection nozzle 134b, and a second injector 140 having a second small injection nozzle 144b but not a second large injection nozzle 142b. Even in this case, the flow rate of the secondary air injected by the first injector 130 can be made different from the flow rate of the secondary air injected by the second injector 140. This allows a circulating flow of secondary air to be formed in the internal space of the furnace 10. Therefore, the burner can promote denitrification reactions in the exhaust gas generated by the combustion of fuel gas. This allows the burner to reduce NOx in the exhaust gas.

[0102] In the above embodiment, the flow rate of the secondary air injected by the first injector 130 and the flow rate of the secondary air injected by the second injector 140 are made different by making the diameters of the first large injection port 132b and the first small injection port 134b different and the diameters of the second large injection port 142b and the second small injection port 144b different. However, the flow rate of the secondary air injected by the first injector 130 and the flow rate of the secondary air injected by the second injector 140 may be made different by making the diameters of the first large injection port 132b, the first small injection port 134b, the second large injection port 142b, and the second small injection port 144b substantially equal and making the amount of secondary air supplied by the oxidant supply unit different.

[0103] In the above embodiment, the first large injection port 132b and the first small injection port 134b of the first injection unit 130 and the second large injection port 142b and the second small injection port 144b of the second injection unit 140 inject secondary air at substantially the same flow rate. However, the flow rate of the secondary air injected from the first injection unit 130 and the flow rate of the secondary air injected from the second injection unit 140 may be different.

[0104] In the above embodiment, the fuel injection unit 110, the first injection unit 130, and the second injection unit 140 are positioned on the imaginary line V, i.e., the angle between the imaginary line connecting the fuel injection unit 110 and the first injection unit 130 and the imaginary line connecting the fuel injection unit 110 and the second injection unit 140 is 180°. However, the angle between the imaginary line connecting the fuel injection unit 110 and the first injection unit 130 and the imaginary line connecting the fuel injection unit 110 and the second injection unit 140 may be any angle between 90° and 270°. This allows a circulating flow of secondary air to be formed in the internal space of the furnace 10.

[0105] For example, the angle formed by the imaginary line connecting the center of the mixed gas outlet 114b and the center of the first large outlet 132b and the imaginary line connecting the center of the mixed gas outlet 114b and the center of the second small outlet 144b may be 90° or more and 270° or less, and the angle formed by the imaginary line connecting the center of the mixed gas outlet 114b and the center of the first small outlet 134b and the imaginary line connecting the center of the mixed gas outlet 114b and the center of the second large outlet 142b may be 90° or more and 270° or less. The angle formed by the imaginary line connecting the center of mixed gas outlet 114b and the center of first large outlet 132b and the imaginary line connecting the center of mixed gas outlet 114b and the center of second large outlet 142b may be 90° or more and 270° or less, and the angle formed by the imaginary line connecting the center of mixed gas outlet 114b and the center of first small outlet 134b and the imaginary line connecting the center of mixed gas outlet 114b and the center of second small outlet 144b may be 90° or more and 270° or less. The angle formed by the imaginary line connecting the center of mixed gas outlet 114b and the center of gravity of first large outlet 132b and first small outlet 134b and the imaginary line connecting the center of mixed gas outlet 114b and the center of gravity of second large outlet 142b and second small outlet 144b may be 90° or more and 270° or less. Alternatively, the first large injection nozzle 132b, the first small injection nozzle 134b, the second large injection nozzle 142b, and the second small injection nozzle 144b may be provided on a single circumference centered on the fuel injection nozzle.

[0106] Furthermore, when the fuel injection unit 110 has a plurality of fuel injection ports, the first injection unit 130 has a plurality of first injection ports, and the second injection unit 140 has a plurality of second injection ports, the angle formed by an imaginary line connecting the centers of gravity of the plurality of fuel injection ports and the centers of gravity of the plurality of first injection ports and an imaginary line connecting the centers of gravity of the plurality of fuel injection ports and the centers of gravity of the plurality of second injection ports may be greater than or equal to 90° and less than or equal to 270°.

[0107] In addition, the angle formed by an imaginary line connecting at least one of the multiple first injection nozzles of the first injection section 130 to the center of gravity of the fuel injection nozzle and an imaginary line connecting at least one of the multiple second injection nozzles of the second injection section 140 to the center of gravity of the fuel injection nozzle may be greater than or equal to 90° and less than 270°.

[0108] Furthermore, the one or more fuel injection ports of the fuel injection section 110, the one or more first injection ports of the first injection section 130, and the one or more second injection ports of the second injection section 140 may be positioned in a manner that allows a circulating flow of secondary air to be formed in the internal space of the furnace 10.

[0109] In the above embodiment, the flow velocity ratio a / b is 0.05 or more, but the flow velocity ratio a / b may be less than 0.05.

[0110] In the above embodiment, the primary air in the mixed gas is between one-third and two-thirds of the target air amount, and the secondary air is the difference between the amount of primary air and the target air amount. However, there is no limitation on the ratio of the amount of primary air to the amount of secondary air. [Explanation of symbols]

[0111] 10 furnace 100 Burner 110 Fuel injection part 114b Mixed gas injection nozzle (fuel injection nozzle) 120 Fuel supply section 130 1st injection part 132b 1st large injection port (1st injection port) 134b 1st small injection port (1st injection port) 140 2nd injection part 142b 2nd large injection port (2nd injection port) 144b 2nd small injection port (2nd injection port) 150 Oxidant supply section 162 Switching control section 200 Burner

Claims

1. a fuel injection unit including one or more fuel injection ports provided toward the interior space of the furnace; a first injection unit including one or more first injection ports spaced apart from the fuel injection port and directed toward the interior space of the furnace; a second injection unit including one or more second injection ports spaced apart from the fuel injection port and directed toward the interior space of the furnace; a fuel supply unit that supplies a fuel gas containing at least ammonia to the fuel injection unit; an oxidant supply unit that supplies an oxidant gas to the first injection unit and the second injection unit; a switching control unit that alternates between a first state in which a flow rate of the oxidant gas injected by the first injector is greater than a flow rate of the oxidant gas injected by the second injector and a second state in which a flow rate of the oxidant gas injected by the first injector is smaller than a flow rate of the oxidant gas injected by the second injector; Equipped with The first injection nozzle has a first large injection nozzle and a first small injection nozzle having a diameter smaller than that of the first large injection nozzle, The second injection port has a second large injection port and a second small injection port having a smaller diameter than the second large injection port, The switching control unit In the first state, the oxidant gas is injected from the first large injection port and the second small injection port, and injection of the oxidant gas from the first small injection port and the second large injection port is stopped; a burner that, in the second state, stops injection of the oxidant gas from the first large injection nozzle and the second small injection nozzle, and injects the oxidant gas from the first small injection nozzle and the second large injection nozzle.

2. 2. The burner according to claim 1, wherein the flow rate of the oxidant gas injected by one of the first injection section and the second injection section is 2.3 times or more and less than 6.3 times the flow rate of the oxidant gas injected by the other of the first injection section and the second injection section.

3. 3. A burner as described in claim 1 or 2, wherein an angle formed between an imaginary line connecting the center of the fuel injection port, the center of the first large injection port, and the center of the first small injection port and an imaginary line connecting the center of the fuel injection port, the center of the second large injection port, and the center of the second small injection port is greater than or equal to 90° and less than 270°.

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