Burner

Abstract

To provide a burner that can be prevented from being burnt due to radiation heat from hydrogen flame when using a hydrogen gas as fuel.SOLUTION: A burner of one embodiment of this disclosure includes: a fuel nozzle 2 for jetting a hydrogen gas forward from a tip jet 2e; and an air delivery pipe 3 for delivering combustion air forward from the periphery of the fuel nozzle 2. The fuel nozzle 2 jets a hydrogen gas from the jet 2e at a jetting speed within a range between 750 m / s or more and 850 m / s or less.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a burner for use in a boiler or the like. [Background technology]

[0002] In recent years, hydrogen has been used as a fuel, as the only product produced when it is burned is water. 2 Hydrogen has attracted attention as a clean fuel with low environmental impact that does not emit harmful substances, and its use as a fuel in burners has also been proposed.

[0003] For example, Patent Document 1 describes a burner that is characterized by having a plurality of fuel injection holes for injecting fuel oil, a plurality of hydrogen injection holes for injecting hydrogen from the periphery of each of the fuel injection holes, and an air supply unit for supplying combustion air from the periphery of each of the hydrogen injection holes. In the burner described in Patent Document 1, hydrogen is injected around the fuel injection hole, so that a hydrogen region formed by the injection of hydrogen exists around the fuel injection hole. Therefore, the fuel oil injected from the fuel injection hole is injected into the hydrogen region existing around the fuel injection hole before meeting the air existing on the periphery. In this hydrogen region, hydrogen has a faster combustion speed than fuel oil, so the combustion of hydrogen takes precedence over the combustion of fuel oil. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2017-138017 A Summary of the Invention [Problem to be solved by the invention]

[0005] The configuration of Patent Document 1 does not take into consideration the burner damage caused by radiant heat from the flame of hydrogen, which has a faster combustion speed than fuel oil.

[0006] The present disclosure has been made to solve the above-mentioned problems, and aims to provide a burner that can prevent burn damage due to radiant heat from a hydrogen flame when hydrogen gas is used as fuel. [Means for solving the problem]

[0007] In order to achieve the above-mentioned objective, a burner according to one embodiment of the present disclosure comprises a fuel nozzle that sprays hydrogen gas forward from a nozzle at the tip, and an air delivery pipe that delivers combustion air forward from around the fuel nozzle, and the fuel nozzle sprays hydrogen gas from the nozzle at a spray speed in the range of 750 m / s or more and 850 m / s or less. Effect of the Invention

[0008] The present disclosure has the above-described configuration and has an effect of providing a burner that can prevent burn damage due to radiant heat from a hydrogen flame when hydrogen gas is used as fuel. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram showing a cross section of a burner according to a first embodiment. [Diagram 2] FIG. 2 is a schematic front view of the tip portion of the burner shown in FIG. [Diagram 3] FIG. 3 is a schematic diagram showing a cross section of a burner according to the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, preferred embodiments of the present disclosure will be described with reference to the drawings. In the following, the same or corresponding elements are denoted by the same reference numerals throughout the drawings, and duplicated descriptions thereof may be omitted. In addition, the drawings are schematic illustrations of the respective components for ease of understanding, and shapes, dimensional ratios, and the like may not be accurately depicted.

[0011] (First embodiment) Fig. 1 is a schematic diagram showing a cross section of a burner according to a first embodiment of the present invention, Fig. 2 is a schematic diagram showing a tip portion of the burner shown in Fig. 1 as viewed from the front.

[0012] A burner 1A as an example of the first embodiment is disposed in a burner mounting hole 12 opened in the wall of a combustion chamber 11 of a boiler 10. This burner 1A includes a plurality of fuel nozzles 2, an air delivery pipe 3, and first and second swirl vanes 4 and 5. The fuel nozzle 2 receives hydrogen gas F1 as fuel from a base end side by a hydrogen gas supply device 7, and sprays the hydrogen gas forward from a nozzle 2e at the tip. The fuel nozzle 2 may be configured to include a plurality of nozzles.

[0013] The fuel nozzles 2 include a fuel nozzle 2a arranged on the central axis CL of the burner 1A, and a plurality of fuel nozzles 2b arranged on the same circumference centered on the central axis CL when viewed from the direction of the central axis CL. In this example, six fuel nozzles 2b arranged on the same circumference are provided, but the number is not limited to this.

[0014] The air delivery pipe 3 has a cylindrical pipe portion having a central axis CL as a center line, and a plurality of fuel nozzles 2 are arranged inside the cylindrical pipe portion. The air delivery pipe 3 delivers combustion air A supplied from the base end side from around the fuel nozzles 2 to the combustion chamber 11 in front.

[0015] A first swirl vane 4 is disposed near the tip of the burner 1A between the central fuel nozzle 2a and the multiple fuel nozzles 2b. A second swirl vane 5 is disposed near the tip of the burner 1A between the multiple fuel nozzles 2b and the inner wall of the air delivery pipe 3. The first and second swirl vanes 4, 5 are well-known vanes having multiple blades made of flat plates. Combustion air A supplied to the air delivery pipe 3 is swirled by the first and second swirl vanes 4, 5 and delivered to the combustion chamber 11 in front.

[0016] The hydrogen gas supply device 7 includes, for example, a hydrogen fuel storage tank, a compressor that pressurizes hydrogen gas supplied from the hydrogen fuel storage tank, and a pressure regulating valve that adjusts the hydrogen gas pressurized by the compressor to hydrogen gas F1 at a predetermined supply pressure and delivers it to the fuel nozzle 2.

[0017] In this embodiment, the fuel nozzle 2 is configured to inject hydrogen gas from the nozzle 2e at an injection speed in the range of 750 m / s to 850 m / s. In this example, when the supply pressure of the hydrogen gas F1 supplied to the fuel nozzle 2 is in the range of 300 kPa to 400 kPa, the aperture of the nozzle 2e is determined so that the injection speed of the hydrogen gas from the nozzle 2e of the fuel nozzle 2 is in the range of 750 m / s to 850 m / s.

[0018] By setting the injection speed of hydrogen gas from the nozzle 2e of the fuel nozzle 2 in the range of 750 m / s to 850 m / s, the distance in the direction of the central axis CL from the tip of the fuel nozzle 2 to the peak temperature part of the hydrogen flame can be set to approximately 2.5 m to 3.0 m. This makes it possible to keep the temperature of the tip part of the burner 1A, including the tip of the fuel nozzle 2 and its surrounding area, to around 500 to 600°C, preventing burnout of the burner 1A due to radiant heat from the hydrogen flame.

[0019] In a conventional natural gas-fired burner, the injection speed at the nozzle of the fuel nozzle that injects natural gas is, for example, in the range of 150 m / s to 250 m / s. In this case, the distance from the tip of the fuel nozzle to the peak temperature part of the natural gas flame in the direction of the central axis CL is about 0.5 m, and the temperature of the tip part of the burner is about 500 to 600°C.

[0020] However, hydrogen gas has a faster combustion speed and a higher flame temperature than natural gas, so in this embodiment, the injection speed of the hydrogen gas injected from the fuel nozzle 2 is made faster than that of a natural gas-fired burner, and the distance from the tip of the fuel nozzle 2 to the peak temperature part of the flame in the direction of the central axis CL is made longer, so that the temperature of the tip part of the burner 1A becomes approximately the same as that of a natural gas-fired burner, thereby preventing the burner 1A from burning out.

[0021] In this embodiment, by setting the injection speed of hydrogen gas in the fuel nozzle 2 to 750 m / s or more, the distance from the tip of the fuel nozzle 2 to the peak temperature part of the hydrogen flame in the direction of the central axis CL can be set to about 2.5 m or more. In addition, the faster the injection speed of hydrogen gas is, the longer the distance from the tip of the fuel nozzle 2 to the peak temperature part of the hydrogen flame in the direction of the central axis CL can be. However, if the flame is formed at a position too far away from the tip of the fuel nozzle 2, the flame will lift and the stability of the flame will be impaired. Therefore, it is preferable to set the distance from the tip of the fuel nozzle 2 to the peak temperature part of the hydrogen flame in the direction of the central axis CL to about 3.0 m or less. For this reason, the injection speed of hydrogen gas is set to 850 m / s or less.

[0022] The burner 1A of this example was installed in a test furnace and a combustion test was performed. In the burner 1A of this example, the total cross-sectional area of ​​the nozzles 2e of the seven fuel nozzles 2 is 0.00051 m 2 When the supply pressure of the hydrogen gas F1 was 330 kPa, the injection speed of the hydrogen gas from the nozzle 2e of the fuel nozzle 2 was 810 m / s. The distance in the direction of the central axis CL from the tip of the burner 1A, which is the tip of the fuel nozzle 2, to the peak temperature part of the hydrogen flame was approximately 2.5 m.

[0023] In addition, by setting the injection speed of hydrogen gas from the nozzle 2e of the fuel nozzle 2 in the range of 750 m / s or more and 850 m / s or less, the hydrogen flame becomes a very elongated flame and the flame surface area is increased, thereby reducing the number of areas in the flame that become locally hot and reducing the amount of NOx generated by high temperatures.

[0024] 1, the arrangement and number of the multiple fuel nozzles 2 can be changed as appropriate. For example, a configuration may be adopted in which there is no fuel nozzle 2a arranged on the central axis CL. Also, a configuration may be adopted in which there is only one fuel nozzle 2a arranged on the central axis CL, with no surrounding fuel nozzles 2b.

[0025] Second embodiment Fig. 3 is a schematic diagram showing a cross section of a burner according to a second embodiment of the present invention, in which the same parts as those in Fig. 1 are denoted by the same reference numerals.

[0026] While the burner 1A shown in FIG. 1 is a hydrogen-only burner fueled only by hydrogen gas, the burner 1B shown in FIG. 3 is a multi-fuel burner fueled by hydrogen gas and liquid fuel. In this burner 1B, the fuel nozzle 2a arranged on the central axis CL in the burner 1A shown in FIG. 1 is changed to a fuel nozzle 6 to which liquid fuel F2 such as heavy oil is supplied. The other configuration is basically the same as that of the burner 1A shown in FIG. 1. In this embodiment, the fuel nozzle 2 that injects hydrogen gas is the first fuel nozzle, and the fuel nozzle 6 that injects liquid fuel forward is the second fuel nozzle. The injection direction of the liquid fuel from the nozzle 6e of the fuel nozzle 6 is a direction approximately parallel to the central axis CL of the burner 1B. In addition, when the fuel nozzle 6 has a plurality of nozzles, the angle of each nozzle may be inclined by 30° to 60° with respect to the central axis CL of the burner 1B.

[0027] The fuel nozzle 6 injects liquid fuel forward from a nozzle hole 6e at the tip end by being supplied with liquid fuel F2 from the base end side by the liquid fuel supply device 8. The aperture of the nozzle hole 6e of the fuel nozzle 6 and the supply pressure of the liquid fuel F2 from the liquid fuel supply device 8 are determined so that the liquid fuel is injected from the nozzle hole 6e at an injection speed slower than the injection speed of hydrogen gas in the fuel nozzle 2.

[0028] The liquid fuel supply device 8 includes, for example, a liquid fuel tank, a pump that pressure-feeds the liquid fuel supplied from the liquid fuel tank, and a pressure regulating valve that adjusts the liquid fuel pressure-feeded by the pump to liquid fuel F2 at a predetermined supply pressure and delivers it to the fuel nozzle 6.

[0029] In the burner 1B of this example, as in the case of the burner 1A described above, the fuel nozzle 2 injects hydrogen gas from the nozzle hole 2e at an injection speed in the range of 750 m / s or more and 850 m / s or less. As a result, as in the case of the burner 1A described above, the temperature at the tip of the burner 1B can be kept at about 500 to 600°C, and the burner 1B can be prevented from being burned out by the heat radiated from the hydrogen flame. In addition, the hydrogen flame becomes a very elongated flame, which reduces the number of locally high-temperature parts in the flame, and reduces the amount of NOx generated.

[0030] In addition, the liquid fuel is injected from the fuel nozzle 6 at a slower injection speed than the injection speed of the hydrogen gas from the fuel nozzle 2. This allows the position of the peak temperature part of the liquid fuel flame in the direction of the central axis CL of the burner 1B to be formed closer to the tip of the burner 1B than the position of the peak temperature part of the hydrogen flame. By shifting the position of the peak temperature part of the liquid fuel flame from the position of the peak temperature part of the hydrogen flame in this way, it is possible to reduce the number of parts in the flame that become locally hot, and to reduce the amount of NOx generated. In addition, in this case, the liquid fuel takes in and burns the combustion air before the hydrogen gas, so the hydrogen gas takes in and burns the combustion air with a reduced absolute amount. This slows down the combustion reaction of hydrogen, which has a higher flame temperature than the liquid fuel, and reduces the amount of NOx generated.

[0031] Although the peak temperature of the flame of a liquid fuel such as heavy oil is lower than that of a hydrogen flame, the peak temperature portion of the flame of the liquid fuel is closer to the tip of the burner 1B than the peak temperature portion of the hydrogen flame. Here, the injection speed of the liquid fuel from the fuel nozzle 6 can be determined so that the peak temperature portion of the flame of the liquid fuel is located at a position that does not cause burn damage to the tip of the burner 1B.

[0032] From the above description, many improvements and other embodiments of the present disclosure will be apparent to those skilled in the art. Therefore, the above description should be construed as merely illustrative and is provided for the purpose of teaching those skilled in the art the best mode for carrying out the present disclosure. Details of the structure and / or function thereof may be substantially changed without departing from the spirit of the present disclosure.

[0033] Summary of the Disclosure The burner according to the first aspect of the present disclosure comprises a fuel nozzle that sprays hydrogen gas forward from a nozzle at the tip, and an air delivery pipe that delivers combustion air forward from around the fuel nozzle, and the fuel nozzle sprays hydrogen gas from the nozzle at a spray speed in the range of 750 m / s or more and 850 m / s or less.

[0034] With this configuration, by setting the injection speed of hydrogen gas from the fuel nozzle outlet in the range of 750 m / s to 850 m / s, the distance from the tip of the fuel nozzle to the peak temperature part of the hydrogen flame can be set to approximately 2.5 m to 3.0 m. This makes it possible to keep the temperature of the tip of the fuel nozzle and its surrounding area at around 500-600°C, preventing burner damage due to radiant heat from the hydrogen flame.

[0035] A burner according to a second aspect of the present disclosure is the burner according to the first aspect, in which the diameter of the nozzle hole is determined so that the injection speed of hydrogen gas from the nozzle hole of the fuel nozzle is in the range of 750 m / s to 850 m / s when the supply pressure of hydrogen gas supplied to the fuel nozzle is in the range of 300 kPa to 400 kPa. In this manner, the diameter of the nozzle hole of the fuel nozzle can be determined.

[0036] A burner according to a third aspect of the present disclosure is the burner according to the first or second aspect, wherein the fuel nozzle is a first fuel nozzle and further comprises a second fuel nozzle that sprays liquid fuel forward from a nozzle at a tip, and the second fuel nozzle sprays liquid fuel from the nozzle at a spray speed slower than the spray speed of hydrogen gas from the first fuel nozzle.

[0037] According to this configuration, a multi-fuel burner using hydrogen gas and liquid fuel as fuel can be realized. In addition, the position of the peak temperature part of the flame of the liquid fuel in the central axial direction of the burner can be formed at a position closer to the tip of the burner than the position of the peak temperature part of the hydrogen flame. By shifting the position of the peak temperature part of the flame of the liquid fuel and the position of the peak temperature part of the hydrogen flame in this way, it is possible to reduce the number of parts in the flame that become locally hot, and the amount of NOx generated can be reduced. In addition, in this case, since the liquid fuel takes in and burns the combustion air before the hydrogen gas, the hydrogen gas takes in and burns the combustion air with a reduced absolute amount. This slows down the combustion reaction of hydrogen, which has a higher flame temperature than the liquid fuel, and reduces the amount of NOx generated. [Explanation of symbols]

[0038] 1A, 1B Burner 2,6 Fuel nozzle 3 Air delivery pipe

Claims

1. A fuel nozzle that injects hydrogen gas forward from a nozzle at the tip; an air delivery pipe that delivers combustion air forward from around the fuel nozzle, The fuel nozzle injects hydrogen gas from a nozzle hole at an injection speed in the range of 750 m / s or more and 850 m / s or less.

2. the diameter of the nozzle hole is determined so that the injection speed of the hydrogen gas from the nozzle hole of the fuel nozzle is in the range of 750 m / s to 850 m / s when the supply pressure of the hydrogen gas supplied to the fuel nozzle is in the range of 300 kPa to 400 kPa, 2. A burner according to claim 1.

3. the fuel nozzle is a first fuel nozzle; a second fuel nozzle that injects liquid fuel forward from a nozzle hole at the tip thereof; the second fuel nozzle injects liquid fuel from a nozzle hole at an injection velocity slower than an injection velocity of hydrogen gas from the first fuel nozzle; A burner according to claim 1 or 2.

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