Burner

Abstract

To provide a burner that can be operated even when ammonia, which is one of the flame-retardant fuels, is used as fuel by supplying air from an air supply device with a supply pressure lower than that of a compressor. [Solution] The burner 1 has a tubular space 20, a combustion tube base 21, an inner flow passage 22, an outer flow passage 23 to which air A sent from an air supply device 9 is supplied, a plurality of swirl vanes 24 for forming a swirl flow, inter-blade flow passages 25 formed between adjacent swirl vanes 24, and a fuel supply section 26 consisting of at least one selected from the group consisting of a first fuel supply section 261 capable of supplying a first fuel F1 into the outer flow passage 23, a second fuel supply section 262 capable of supplying a second fuel F2 into the combustion tube base 21, and a third fuel supply section 263 capable of supplying a third fuel F3 into the inter-blade flow passage 25 or the tubular space 20. In the burner 1, a swirl flow is formed in the tubular space 20 by a gas flow that passes through the inter-blade flow passages 25 and is ejected into the tubular space 20,

Description

[Technical Field]

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

[0002] Conventionally, as described in Patent Document 1, a combustor (burner) has been disclosed that has a gas supply pipe, a first supply section having a first gas flow path formed therein and connected to the gas supply pipe so as to extend tangentially to the side wall of the gas supply pipe, a second supply section having a second gas flow path formed therein and connected to the gas supply pipe so as to extend tangentially to the side wall of the gas supply pipe, and a combustion tube into which mixed gas is supplied from the gas supply pipe and a flame is formed inside the tube.

[0003] In this burner, the mixed gas is supplied to the gas supply pipe from two different tangential directions through the first and second gas passages, flows along the inner circumferential surface of the side wall of the gas supply pipe, and swirls inside the gas chamber. The mixed gas supplied to the gas supply pipe rises while swirling inside the gas chamber of the gas supply pipe, and is supplied to the combustion pipe where it is combusted. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6846713 Summary of the Invention [Problem to be solved by the invention]

[0005] The conventional burners described above are burners that allow premixed gas to flow in tangentially from two narrow inlets. This type of burner has a small gas inlet area, resulting in large pressure loss. Therefore, to address the pressure loss, a compressor (compressed air supply device) is required to supply air. However, for commercial burners, from the perspective of cost reduction, there is a demand for burners that can be operated using air supplied by an air supply device such as a blower, which has a lower supply pressure than a compressor.

[0006] In recent years, ammonia has been attracting attention as a fuel that does not emit carbon dioxide. Considering that efforts to utilize non-flammable fuels such as ammonia as fuel will progress in the future, it is desirable that at least ammonia can be burned as a fuel.

[0007] The present invention has been made in view of the above problems, and aims to provide a burner that can be operated even when ammonia, which is a type of flame-retardant fuel, is used as fuel by supplying air from an air supply device with a supply pressure lower than that of a compressor. [Means for solving the problem]

[0008] One aspect of the present invention is a tubular space provided in the center of the burner; a combustion tube base portion having a bottom and a tubular shape, the combustion tube base portion being connected to one end of the tubular space; On the outer periphery of the tubular space Along an inner flow path provided therein; an outer flow path that is in communication with the inner flow path and is provided on an outer periphery of the inner flow path, and to which air sent from an air supply device is supplied; a plurality of swirl vanes for forming a swirl flow provided between the inner flow path and the tubular space so as to surround an outer periphery of the tubular space; an inter-blade flow passage formed between each adjacent one of the swirl vanes and communicating the inner flow passage with the tubular space; a fuel supply unit including at least one selected from the group consisting of a first fuel supply unit capable of supplying a first fuel into the outer flow passage, a second fuel supply unit capable of supplying a second fuel into the combustion tube base, and a third fuel supply unit capable of supplying a third fuel into the inter-blade flow passage or the tubular space, the inter-blade flow passage is defined by inner surfaces of the adjacent swirl vanes on the flow passage side, a burner rear cover provided on the combustion tube base side, and a burner front cover provided on the opposite side to the combustion tube base side, a gas flow passing through the inter-blade passage and ejected into the tubular space forms a swirling flow in the tubular space; It's in Burna. [Effects of the Invention]

[0009] The burner has the above-described configuration. In the burner, air sent from an air supply device, such as a blower, whose supply pressure is lower than that of a compressor, flows through an outer flow passage and into an inner flow passage provided on the inner periphery of the outer flow passage. The air that has flowed into the inner flow passage passes through a plurality of inter-blade flow passages formed between a plurality of swirl vanes arranged between the inner flow passage and a tubular space provided inside the inner flow passage, and is ejected into the tubular space.

[0010] In the burner, at least one of a first fuel, a second fuel, and a third fuel is supplied by a fuel supply unit. That is, when the first fuel is supplied into the outer flow passage by the first fuel supply unit and / or the third fuel is supplied into the inter-blade flow passage by the third fuel supply unit, the burner can eject a gas flow of premixed gas of at least one of the first fuel and the third fuel and air into the tubular space. Also, when the second fuel is supplied into the combustion tube base by the second fuel supply unit and / or the third fuel is supplied into the tubular space by the third fuel supply unit, the burner can eject a gas flow of air into the tubular space, and then the at least one of the second fuel and the third fuel is mixed with the air.

[0011] In the burner, a swirling flow is formed within the tubular space by the gas flow ejected into the tubular space through the multiple inter-blade flow passages. In other words, the burner can eject a gas flow into the tubular space from the entire circumference. In this way, the burner can increase the supply area of ​​the gas flow into the tubular space, thereby reducing pressure loss and necessitating air supply from an air supply device with a lower supply pressure than a compressor. The burner can also ignite the fuel contained in the swirling flow using a spark plug or flame rod, thereby forming a flame by combustion of the fuel in the swirling flow, even when ammonia, a type of non-flammable fuel, is used as the fuel. The burner has a space at the base of the combustion tube at a position where the high-speed gas flow enters from the inter-blade flow passage and where the downstream portion of the gas flow is avoided. Therefore, the upstream edge of the flame is formed in this space at the base of the combustion tube. This prevents the upstream edge of the flame from being blown out, thereby achieving a significant effect of improving the flame stability of the entire combustion.

[0012] Therefore, the burner can be operated by supplying air from an air supply device with a lower supply pressure than that of a compressor, even when ammonia, which is one of the flame-retardant fuels, is used as fuel. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a schematic diagram of a burner according to an embodiment (with a burner front cover removed for ease of explanation) viewed from the front of the burner. [Figure 2] FIG. 2 is a schematic diagram showing a cross section of a burner according to an embodiment. [Figure 3] FIG. 3 is a schematic diagram showing an example in which a combustion tube tip and a second fuel supply unit are attached to a burner according to the embodiment. [Figure 4] FIG. 4 is a schematic diagram showing a burner according to the embodiment in which the angle of the swirl vanes, which are configured so that the angle can be changed by a lever, is set to 0°. [Figure 5]FIG. 5 is a schematic diagram showing a burner according to the embodiment in which the angle of the swirl vanes, which are configured so that the angle can be changed by a lever, is set to 45°. [Figure 6] FIG. 6 is a schematic diagram showing a burner according to the embodiment in which the angle of the swirl vanes, which are configured so that the angle can be changed by a lever, is set to 90°. [Figure 7] FIG. 7 is a view of a burner according to an embodiment that was actually fabricated (however, for convenience of explanation, the burner front cover has been removed) as viewed from the front of the burner. [Figure 8] Figure 8 is a perspective view of a burner according to an embodiment that was actually fabricated (however, for convenience of explanation, the burner front cover is removed), viewed obliquely from the front, with the angle of the swirl vanes, which are angle-adjustable by a lever, set to 0°. [Figure 9] Figure 9 is an oblique view of a burner according to an embodiment that was actually manufactured (however, for convenience of explanation, the burner front cover has been removed), in which the angle of the swirl vanes, which can be adjusted using a lever, is set to 90°. [Figure 10] FIG. 10 is an enlarged perspective view of the internal structure of FIG. [Figure 11] FIG. 11 is a perspective view of the burner according to the embodiment actually fabricated and shown in FIGS. 7 to 10, with the burner front cover and lever attached, as viewed obliquely from the front. [Figure 12] FIG. 12 is a view showing an example of a third fuel supply unit in the burner according to the embodiment, as seen from the front of the burner. [Figure 13] FIG. 13 is a diagram showing an example of a third fuel supply unit in the burner according to the embodiment, as seen from an oblique direction in front of the burner. [Figure 14] FIG. 14 is a diagram for explaining a method for calculating the swirl number S and the inflow swirl number S′ of the swirl flow formed in the burner according to the embodiment having flat plate-shaped swirl vanes. [Figure 15]FIG. 15 is a diagram for explaining a method for calculating the swirl number S and the inflow swirl number S' of the swirl flow formed in the burner according to the embodiment having swirl vanes in the shape of a flat curved plate. [Figure 16] FIG. 16 is a diagram showing an example of the arrangement of swirl vanes before the turbulence generating section is attached, as seen from the front of the burner according to the embodiment. [Figure 17] FIG. 17 is a diagram showing an example of a burner according to an embodiment in which a turbulence generating section using a ring member is attached to a swirl vane, as seen from the front of the burner. [Figure 18] FIG. 18 is a diagram showing an example of a burner according to an embodiment, seen from the front of the burner, in which a turbulence generating section using a convex portion is attached to a swirl vane. [Figure 19] FIG. 19 is a diagram showing an example of a burner according to an embodiment, in which a turbulence generating section using a convex portion is attached to a swirl vane, as seen from an oblique direction in front of the burner. [Figure 20] FIG. 20 is a diagram showing an example of a burner according to an embodiment, seen from the front of the burner, in which a turbulence generating section made of a columnar member is attached to a swirl vane. [Figure 21] FIG. 21 is a diagram showing the dimensions of a burner according to an embodiment that was actually fabricated. [Figure 22] FIG. 22 is a diagram showing a design drawing (cross-sectional view) of a small combustion furnace fabricated for a combustion test of the burner according to the embodiment that was actually fabricated. [Figure 23] FIG. 23 is a diagram showing a design drawing (top view) of a small combustion furnace that was fabricated for a combustion test of the burner according to the embodiment that was actually fabricated. [Figure 24] FIG. 24 is a diagram showing a mapping of the combustion state obtained in Experimental Example 1 (exit passage width of the inter-blade passage h=1 mm, swirl number S=4.5, inflow swirl number S′=0.65). [Figure 25] FIG. 25 is a diagram showing a mapping of the combustion state obtained in Experimental Example 1 (exit passage width of the inter-blade passage h=2 mm, swirl number S=2.2, inflow swirl number S′=0.62). [Figure 26]FIG. 26 is a diagram showing a mapping of the combustion state obtained in Experimental Example 1 (exit passage width of the inter-blade passage h=3 mm, swirl number S=1.4, inflow swirl number S′=0.58). [Figure 27] FIG. 27 is a diagram showing a mapping of the combustion state obtained in Experimental Example 1 (exit passage width of the inter-blade passage h=4 mm, swirl number S=1.0, inflow swirl number S′=0.54). [Figure 28] FIG. 28 is a diagram showing a mapping of the combustion state obtained in Experimental Example 1 (exit passage width of the inter-blade passage h=5 mm, swirl number S=0.79, inflow swirl number S′=0.49). [Figure 29] FIG. 29 is a diagram showing a mapping of the combustion state obtained in Experimental Example 1 (exit passage width of the inter-blade passage h=6 mm, swirl number S=0.62, inflow swirl number S′=0.43). [Figure 30] FIG. 30 is a diagram showing a mapping of the combustion state obtained in Experimental Example 1 (exit passage width of the inter-blade passage h=8 mm, swirl number S=0.39, inflow swirl number S′=0.28). [Figure 31] FIG. 31 is a diagram showing a mapping of the combustion state obtained in Experimental Example 1 (exit passage width of the inter-blade passage h=10 mm, swirl number S=0.19, inflow swirl number S′=0.10). [Figure 32] FIG. 32 is a diagram showing mapping of the combustion state obtained in Experimental Example 1 (when the outlet flow passage width h of the inter-blade flow passage is 1, 2, 3, 4 mm). [Figure 33] FIG. 33 is a graph showing the emission concentration of nitric oxide NO obtained in Experimental Example 1. [Figure 34] FIG. 34 is a diagram showing the emission concentration of nitrogen dioxide NO2 obtained in Experimental Example 1. [Figure 35] FIG. 35 is a graph showing the discharge concentration of nitric oxide NO obtained in Experimental Example 2. [Figure 36] FIG. 36 is a diagram showing the emission concentration of nitrogen dioxide NO2 obtained in Experimental Example 2. DETAILED DESCRIPTION OF THE INVENTION

[0014] An embodiment of a burner according to the present invention will be described in detail below with reference to the drawings. Note that the burner according to the present invention is not limited to the examples shown in the following embodiment. Furthermore, the lower and upper limits of the numerical ranges shown below can be arbitrarily combined, including the values ​​described in the experimental examples (omitted below).

[0015] The burner of this embodiment will be described with reference to Figures 1 to 20. Figures 7 to 11 show burners that were actually manufactured based on Figures 1 to 6, and in describing the burner of this embodiment, these drawings of the actually manufactured burners can also be referred to as appropriate.

[0016] As illustrated in FIGS. 1 to 20 , the burner 1 of this embodiment has a tubular space 20, a combustion tube base 21, an inner flow path 22, an outer flow path 23, a plurality of swirl vanes 24, an inter-blade flow path 25, and a fuel supply unit 26. In the burner 1, a swirl flow is formed in the tubular space 20 by a gas flow that passes through the inter-blade flow path 25 and is ejected into the tubular space 20. The burner 1 can be primarily made of a metal material such as stainless steel, a heat-resistant material such as ceramic (including glass), or a combination of these. Hereinafter, the flame-forming side of the burner 1 will be referred to as the front of the burner 1, and the opposite side as the rear of the burner 1. Furthermore, when viewed from a predetermined reference position, the side from which air A flows will be referred to as the upstream side, and the side from which air A flows will be referred to as the downstream side.

[0017] The tubular space 20 is provided in the burner central portion, which is the center of the burner 1. The burner central portion can also be called the burner center portion. The tubular space 20 includes the central axis L of the burner 1 and is configured as a space that exhibits a tubular shape around the central axis L. Here, the tubular axis of the tubular space 20 coincides with the burner central axis L of the burner 1.

[0018] The combustion tube base 21 is formed in a tubular shape with a bottom. The combustion tube base 21 is connected to one end of the tubular space 20. Specifically, the combustion tube base 21 is connected to the tubular space 20 by having an opening of the combustion tube base 21 connected to the rear end of the tubular space 20. The tube axis of the combustion tube base 21 coincides with the burner central axis L of the burner 1.

[0019] The inner flow passage 22 is provided on the outer periphery of the tubular space 20. Specifically, the inner flow passage 22 is provided along the outer periphery of the tubular space 20 so as to be coaxial with the tubular space 20. More specifically, the inner flow passage 22 is defined by a plate-shaped burner rear cover portion 31 provided on the combustion tube base 21 side, a plate-shaped burner front cover portion 32 provided on the opposite side from the combustion tube base 21 side, and a plate member 33 provided circumferentially between the inner flow passage 22 and the outer flow passage 23. The plate member 33 is formed so as to follow the outer periphery of the inner flow passage 22 (the inner periphery of the outer flow passage 23), and a large number of through holes 331 are formed in the plate member 33 (see FIGS. 7 to 10, especially FIG. 10).

[0020] The outer flow passage 23 communicates with the inner flow passage 22 and is provided on the outer periphery of the inner flow passage 22. Specifically, the outer flow passage 23 is provided along the outer periphery of the inner flow passage 22. More specifically, the outer flow passage 23 is defined by a burner rear cover 31, a plate-shaped outer flow passage front wall 231 provided on the side opposite the combustion tube base 21, an outer flow passage outer periphery wall 232 provided between the burner rear cover 31 and the outer flow passage front wall 231, and a plate member 33. The inner flow passage 22 and the outer flow passage 23 can communicate with each other via the plate member 33 in which the above-mentioned numerous through holes 331 are formed. Note that, although a circular shape is exemplified here as the shape of the through holes 331, the shape of the through holes 331 is not particularly limited and may be a polygonal shape (triangle, square, etc.), an elliptical shape, a racetrack shape, a slit shape, or the like. Furthermore, the plate member 33 may include a mesh member.

[0021] An air inlet 233 is formed at one end of the outer flow path 23. The outer flow path 23 can be formed so that the cross-sectional area of ​​the flow path gradually decreases from the air inlet 233 formed at one end of the outer flow path 23 toward the other end of the outer flow path 23, from the viewpoints of making it difficult for the flow velocity of the air A flowing inside to decrease and making the supply of the air A and the like to the inner flow path 22 uniform.

[0022] The outer flow path 23 is supplied with air A sent from an air supply device (not shown). The air supply device referred to here refers to an air supply device with a lower supply pressure than a compressor, and does not include a compressor. Specifically, the supply pressure of air A from the air supply device can be less than 100 kPa. Examples of such air supply devices include air supply devices that send air, such as a blower. A blower is typically a device that can send air A at a pressure of 10 kPa or more and less than 100 kPa. The air supply device can be integrally connected to the air inlet 233 from the perspective of packaging the burner 1, etc.

[0023] The plurality of swirl vanes 24 are used to form a swirling flow, that is, to form a swirling flow within the tubular space 20. Each swirl vane 24 is provided between the inner flow passage 22 and the tubular space 20 so as to surround the outer periphery of the tubular space 20.

[0024] Specifically, the swirl vanes 24 are arranged at predetermined intervals along the circumferential direction of the tubular space 20. The shape of the swirl vanes 24 is not particularly limited, but here, an example is shown in which the swirl vanes 24 are formed into a rectangular shape from flat plate material. As exemplified in FIG. 15, the swirl vanes 24 may be formed from flat curved plates, which are curved flat plate material. Furthermore, although not shown, the swirl vanes 24 may be formed from curved plates that are entirely curved. In order to impart turbulence and velocity non-uniformity to the swirling flow within the tubular space 20 for the purpose of promoting mixing and combustion, the spacing and angles of the swirl vanes 24 may be made non-uniform, and plate shapes such as flat plates, flat curved plates, and curved plates may be mixed.

[0025] The inter-blade flow passages 25 are flow passages formed between adjacent swirl vanes 24, and connect the inner flow passage 22 to the tubular space 20. Specifically, each inter-blade flow passage 25 can be formed by being mainly partitioned by, for example, the inner surfaces of the flow passage sides of the adjacent swirl vanes 24, the burner rear cover portion 31, and the burner front cover portion 32.

[0026] In the burner 1, the swirl vanes 24 can be configured to have a variable angle, from the viewpoint of making it possible to adjust the swirl number of the swirling flow to be formed (described in detail later). With this configuration, the burner 1 can vary the angle of the swirl vanes 24 to change the flow path cross-sectional area of ​​the inter-blade flow path 25 and the ejection direction of the gas flow ejected into the tubular space 20, thereby making it possible to change the swirl number of the swirling flow.

[0027] Specifically, as illustrated in Figures 4 to 6, the burner 1 can be configured so that the angles of multiple swirl vanes 24 can be simultaneously adjusted by changing the angle of a lever 34 provided outside the outer flow passage 23. In this case, the angles of all of the swirl vanes 24 can be adjusted simultaneously by operating the lever once. Therefore, in this case, by changing the angle of the lever 34, all of the swirl vanes 24 can be moved, and the flow path cross-sectional area of ​​all of the inter-blade flow passages 25 and the gas flow ejection direction can be changed simultaneously. As a result, the swirl number of the swirl flow (described in detail below) can be quickly changed. Note that the angle of the swirl vanes 24 can be adjusted both during non-combustion and combustion.

[0028] In this embodiment, the angles of all swirl vanes 24 can be simultaneously adjusted by operating the lever once, thanks to the following configuration. Specifically, a pair of pins 241 are provided on both side edges (front and rear edges) of each swirl vane 24 facing the tubular space 20. The swirl vanes 24 are attached to fixed ring plates 311 fixed to the burner front cover 32 and the burner rear cover 31, respectively, so that they can rotate around the pins 241 as rotation axes. A movable ring plate 35 is sandwiched between the rear edge of each swirl vane 24 and the burner rear cover 31. The movable ring plate 35 has multiple U-shaped grooves 351 extending radially inward from its outer periphery. The movable ring plate 35 is rotatable in conjunction with the operation of the lever 34. One end of a rod 352 is connected to the end of each swirl vane 24 opposite the end facing the tubular space 20. The other end of each rod 352 is attached so as to be guided by a respective groove 351 in the movable ring plate 35. Therefore, when the angle of the lever 34 is changed, the movable ring plate 35 rotates in conjunction with this, and the rod 352 moves correspondingly, guided by the groove 351, and each swirl vane 24 rotates around the pin 241 as the rotation axis.

[0029] In this embodiment, an example in which the swirl vanes 24 are configured to be angle-variable has been shown, but the swirl vanes 24 may also be fixed so that their angles cannot be varied. In this case, the swirl vanes 24 can be fixed at a predetermined angle in advance so that the swirl number of the swirling flow (described in detail below) falls within an optimum range. With this configuration, the configuration of the burner 1 can be simplified compared to when the swirl vanes 24 are configured to be angle-variable, making it possible to improve the manufacturability of the burner 1 and reduce costs.

[0030] The fuel supply unit 26 is composed of at least one selected from the group consisting of a first fuel supply unit 261, a second fuel supply unit 262, and a third fuel supply unit 263.

[0031] The first fuel supply unit 261 is a portion capable of supplying the first fuel F1 into the outer flow passage 23. The position at which the first fuel F1 is supplied into the outer flow passage 23 is not particularly limited. From the viewpoint of the premixing property (mixing characteristics) of the air A and the first fuel F1, the first fuel supply unit 261 is preferably configured to be capable of supplying the first fuel F1 into the outer flow passage 23 in one end region of the outer flow passage 23 where the air inlet 233 is formed, that is, in an end region on the upstream side of the air flow in the outer flow passage 23. More specifically, in this example, a first fuel nozzle 261b provided at the tip of a pipe 261a connected to a supply source (not shown) of the first fuel F1 is inserted into an outer flow passage outer peripheral wall portion 232, which is one of the partition walls that partition the outer flow passage 23, in the end region on the upstream side of the air flow in the outer flow passage 23, so that the first fuel F1 can be mixed with the air A flowing through the outer flow passage 23 from a nozzle hole 262c.

[0032] The second fuel supply unit 262 is a portion capable of supplying the second fuel F2 into the combustion tube base 21. The position from which the second fuel F2 is supplied into the combustion tube base 21 is not particularly limited. From the viewpoint of mixability and the like, the second fuel supply unit 262 is preferably configured to be able to supply the second fuel F2 from the fuel pipe cylindrical wall of the combustion tube base 21 or the center of the bottom 211 of the combustion tube base 21. Note that the center of the bottom 211 refers to a region within (including on) a circle whose center is the center point of the bottom 211 (the point where the bottom 211 intersects with the tube axis of the combustion tube base 21) and whose radius is 1 / 2 the radius of the bottom 211, preferably 1 / 3 the radius of the bottom 211.

[0033] More specifically, as illustrated in FIG. 3, an example is shown in which a second fuel nozzle (details omitted) provided at the tip of a pipe 262a connected to a supply source (not shown) of the second fuel F2 is inserted into the center of the bottom 211 of the combustion tube base 21, and the second fuel F2 can be mixed into the combustion tube base 21 from a nozzle hole (not shown).

[0034] The second fuel supply unit 262 is preferably configured to supply the second fuel F2 from the center of the bottom 211 of the combustion tube base 21 in a direction inclined with respect to the axial direction of the tubular space 20. More preferably, the second fuel supply unit 262 is configured to supply the second fuel F2 from the center of the bottom 211 of the combustion tube base 21 in a direction inclined with respect to the axial direction of the tubular space 20 and in a direction that reinforces the swirling flow formed in the tubular space 20. In this case, the direction that reinforces the swirling flow refers to a direction in which the swirling flow formed in the tubular space 20 can be strengthened by the injection of the second fuel F2. Compared to fuels with a large theoretical air volume (volume ratio of air to fuel at stoichiometric mixing), such as propane and methane, the fuel jet has a greater reinforcing effect on the swirling flow when using fuels with a small theoretical air volume, such as ammonia and hydrogen. Therefore, the setting of the fuel jet is important. The fuel flow can be used to reinforce the swirl and also to promote mixing of the fuel and air by colliding with the swirling air flow. The direction inclined with respect to the axial direction of the tubular space 20 can be, for example, 30 degrees or more and 60 degrees or less, preferably 40 degrees or more and 50 degrees or less, with respect to the axial direction of the tubular space 20.

[0035] The third fuel supply unit 263 is a portion capable of supplying the third fuel F3 into the inter-blade passage 25 or the tubular space 20. The position at which the third fuel F3 is supplied into the inter-blade passage 25 or the tubular space 20 is not particularly limited. When the third fuel F3 is supplied into the inter-blade passage 25, the third fuel supply unit 263 is preferably located at the outlet of the inter-blade passage 25 or at a position protruding from the outlet into the tubular space 20 from the viewpoint of facilitating pre-mixing of the third fuel F3 into the tubular space 20 and preventing flashback. However, from the viewpoint of improving the mixability of the third fuel F3 with the air A, the third fuel supply unit 263 is preferably configured to be able to supply the third fuel F3 between the inlet and the outlet of the inter-blade passage 25.

[0036] When the third fuel F3 is supplied into the inter-blade passages 25, specifically, for example, as illustrated in FIGS. 12 and 13 , a third fuel nozzle 263b provided in a pipe (not shown) connected to a supply source (not shown) of the third fuel F3 may be inserted into the inter-blade passage 25. The third fuel nozzle 263b may be disposed in all of the plurality of inter-blade passages 25, or may be disposed in some of the plurality of inter-blade passages 25. Note that FIGS. 12 and 13 show an example in which the third fuel nozzle 263b is disposed in each of the plurality of inter-blade passages 25. However, FIGS. 12 and 13 only show the third fuel nozzle 263b necessary for understanding.

[0037] The height direction length of the swirl vane 24 at the nozzle hole 263c of the third fuel nozzle 263b can be preferably ⅓ or less, more preferably ½ or less, of the height of the swirl vane 24 from the viewpoints of reducing pressure loss of the air A flowing through the inter-blade passage 25, the ability to pre-mix the third fuel F3 into the tubular space 20, and the ratio of the air flow rate to the fuel flow rate. The height direction positions of the swirl vanes 24 at the nozzle hole 263c of the third fuel nozzle 263b between adjacent inter-blade passages 25 may be the same or different. In FIGS. 12 and 13 , an example is shown in which the height direction positions of the swirl vanes 24 at the nozzle hole 263c of the third fuel nozzle 263b are alternately arranged above and below between adjacent inter-blade passages 25 from the viewpoints of efficiently pre-mixing the third fuel F3 into the tubular space 20 and promoting diffusion of the third fuel F3 into the air A.

[0038] 12 and 13, the third fuel nozzle 263b is preferably attached to one of the two swirl vanes 24 that form each inter-blade flow passage 25. With this configuration, if the angle of the swirl vanes 24 is adjustable, the third fuel nozzle 263b is less likely to interfere with the swirl vanes 24 when the angle of the swirl vanes 24 is adjusted, and the angle of the swirl vanes 24 can be adjusted to any angle. Furthermore, the angle of the third fuel nozzle 263b can be adjusted simultaneously in accordance with the adjustment of the angle of the swirl vanes 24.

[0039] On the other hand, when the third fuel F3 is supplied to the tubular space 20, the third fuel supply unit 263 is preferably configured to be able to supply the third fuel F3 from the outer periphery of the tubular space 20, from the viewpoint of making it easier to prevent flashback. The outer periphery of the tubular space 20 refers to a region extending from the outer periphery of the tubular space 20 to ¼, preferably ⅕, of the radius of the tubular space 20 in the axial direction of the tubular space 20. Note that an illustration of the case in which the third fuel supply unit 263 supplies the third fuel F3 into the tubular space 20 is omitted.

[0040] The third fuel supply unit 263 is preferably configured to be able to supply the third fuel F3 from the outer peripheral edge of the tubular space 20 in a direction that reinforces the swirling flow formed in the tubular space 20. In this case, the direction that reinforces the swirling flow refers to a direction in which the flow of the swirling flow formed in the tubular space 20 can be strengthened by the ejection of the third fuel F3.

[0041] The burner 1 described above can combust fuel as follows. In the burner 1, air A sent from an air supply device, such as a blower, whose supply pressure is lower than that of a compressor, flows through the outer flow passage 23 and into the inner flow passage 22 provided on the inner periphery of the outer flow passage 23. In this embodiment, the air A flows from the outer flow passage 23 to the inner flow passage 22 through a through-hole 331 in a plate member 33 provided between the outer flow passage 23 and the inner flow passage 22. The air A that has flowed into the inner flow passage 22 passes through a plurality of inter-blade flow passages 25 formed between a plurality of swirl vanes 24 arranged between the inner flow passage 22 and a tubular space 20 provided inside the inner flow passage 22, and is ejected into the tubular space 20.

[0042] In the burner 1, at least one fuel selected from a first fuel F1, a second fuel F2, and a third fuel F3 is supplied by the fuel supply unit 26. That is, when the first fuel F1 is supplied into the outer flow passage 23 by the first fuel supply unit 261 and / or the third fuel F3 is supplied into the inter-blade flow passage 25 by the third fuel supply unit 263, the burner 1 can eject a gas flow of premixed gas containing at least one fuel selected from the first fuel F1 and the third fuel F3 and air A into the tubular space 20. Furthermore, when the second fuel F2 is supplied into the combustion tube base 21 by the second fuel supply unit 262 and / or the third fuel F3 is supplied into the tubular space 20 by the third fuel supply unit 263, the burner 1 can eject a gas flow of air A into the tubular space 20, and then at least one of the second fuel F2 and the third fuel F3 is mixed with the air A (pre-mixing).

[0043] In the burner 1, a swirling flow is formed in the tubular space 20 by the gas flow as described above, which is ejected into the tubular space 20 through the multiple inter-blade flow passages 25. In other words, the burner 1 can eject a gas flow into the tubular space 20 from the entire circumference of the tubular space 20. In this way, the burner 1 can increase the supply area of ​​the gas flow to the tubular space 20, thereby reducing pressure loss and necessitating air supply from an air supply device with a lower supply pressure than a compressor. The burner 1 can ignite the fuel contained in the swirling flow using a spark plug (not shown) or a flame rod (not shown), and can form a flame (sometimes called a tubular flame or a swirl flame) by combustion of the fuel in the swirling flow, even when ammonia, a type of non-flammable fuel, is used as the fuel. In addition, in the burner 1, there is a space within the combustion tube base 21 at a position where the high-speed gas flow enters from the inter-blade flow passage 25 and at a position where the downstream part of the gas flow can be avoided. Therefore, by forming the upstream end of the flame in this space of the combustion tube base 21, the upstream end of the flame is not blown out, which has the great effect of improving the flame stability of the entire combustion.

[0044] Therefore, the burner 1 can be operated by supplying air from an air supply device with a lower supply pressure than that of a compressor, even when ammonia, which is one of the flame-retardant fuels, is used as fuel.

[0045] The burner 1 is capable of burning at least ammonia as fuel, but the fuel is not limited to ammonia. In addition to ammonia, examples of fuels that can be used in the burner 1 include gas fuels such as hydrogen and various hydrocarbons, atomized liquid fuels and volatile fuels such as heavy oil and kerosene, and powdered fuels such as pulverized coal, and these can be used alone or in combination. When at least ammonia is used as fuel, combustion does not involve the emission of carbon dioxide, which can contribute to the realization of a decarbonized society.

[0046] The burner 1 is preferably capable of setting the swirl number S of the swirling flow in the tubular space 20 to 0.79 or more (the inflow swirl number S' to 0.49 or more). When the swirl number is within the above range, the tubular flame formed by the combustion of the fuel contained in the swirling flow has good flame stability, making it easier to achieve stable combustion.

[0047] From the viewpoint of improving the flame stability of the tubular flame, the swirl number S (inflow swirl number S') is more preferably S = 1.4 or more (S' = 0.58 or more), even more preferably S = 2.2 (S' = 0.62 or more), and even more preferably S = 4.5 or more (S' = 0.65 or more). From the viewpoint of avoiding an increase in pressure loss due to a reduction in the inflow area during high swirl, the swirl number S (inflow swirl number S') can be, for example, S = 7.0 or less (S' = 0.66 or less).

[0048] The swirl number S (the inflow swirl number S') is derived from the geometric shape of the swirl vanes 24 when the burner 1 is not burning, and is defined as follows: The inflow swirl number S', listed together with the swirl number S, is based on the definition in the reference book ("Aerodynamics of Bear / Cigar Combustion," edited by Iinuma Kazuo, translated by Tanaka Ryoichi, 1985, Energy Conservation Center).

[0049] Fig. 14 shows an example of the configuration and dimensions of a burner 1 having flat plate-shaped swirl vanes 24, which is used to explain the method of calculating the swirl number S of the swirl flow and the inflow swirl number S'. Also, Fig. 15 shows an example of the configuration and dimensions of a burner 1 having flat curved plate-shaped swirl vanes 24, which is used to explain the method of calculating the swirl number S of the swirl flow and the inflow swirl number S'. These Figs. 14 and 15 are drawings depicting the state of the jet supply cross section perpendicular to the tube axis of the combustion tube base 21.

[0050] In the burner 1 exemplified in Figures 14 and 15, a fluid is supplied to a tubular space 20 as a swirling jet having a tangential velocity component from the outer peripheral surface of the tubular space 20. The jet is supplied in the axial direction of the tubular space 20 over a distance of B [m]. In order to obtain a strong swirl, it is better for the fluid not to have a velocity component in the axial direction (z direction) when it flows into the tubular space 20, and this case will be considered here. The burner 1 (here, the radius R of the tubular space 20) d = radius of the combustion tube cylindrical wall of the combustion tube base 21), the swirling flow (fluid density ρ, total flow rate Q) is ejected at a velocity V from the gap outlet between multiple (N pieces, 16 pieces in the figure and in the actual fabricated example) flat plate swirl vanes (Fig. 14) or flat curved plate swirl vanes (Fig. 15), that is, from the outlet of the inter-blade flow passage 25. The outlet flow passage width of the inter-blade flow passage 25 is assumed to be h. The ejection velocity V0 is given by V0=Q / (N×h×B)=(UπR d 2 ) / (N×h×B). The swirl vane 24 can rotate (or may be non-rotating) around an axis located at a position e from the tip of the vane, at a radial position Rp, with N rotation axis points (for example, Pv on the y-axis and its neighboring Pvn) spaced at equal angular intervals Apn° around the entire circumference, and the set angle is shown as Av° in the figure. Here, the outlet flow passage width h of the inter-blade flow passage 25 is calculated as the length of the line (outlet) connecting the tip E of <swirl vane 1> in the figure (radial position Re, angular position Ape° from the y-axis) to the foot N (radial position Rn) of a perpendicular line drawn from tip E to <swirl vane 2> (tip En) in the figure. Here, the midpoint between E and N on the surface of <swirl vane 2> (straight line N-En) is defined as M (radial position Rm, angular position Am° from the y-axis). Since the jet is ejected at an angle Af° with respect to the vector OM, the tangential component W0 of the jet is calculated as W0 = V0 × sin(Af°). The swirl number S and the inflow swirl number S', which are used as indicators of the swirl strength of a swirling jet, are calculated by the axial flux G of the angular momentum of the swirling flow as follows: φ and axial (z-direction) thrust G z However, since we are dealing with a flow inside a pipe here, the static pressure term can be ignored in the equation for axial thrust.

[0051]

number

[0052]

number

[0053] Here, U and W = W(r) are the axial and tangential components of the velocity in a cross section perpendicular to the tube axis, respectively. r is the radial coordinate with the tube center as the origin. ρ is the gas density, R d is the radius of the tubular space 20 (the radius of the cylindrical wall of the combustion tube at the base 21 of the combustion tube). If the axial velocity component U is considered to be uniform across the cross section, the axial thrust G z is expressed as follows:

[0054]

number

[0055] On the other hand, G φ In the integrand, two types of velocity distribution of W can be set as follows: (1) Focusing on the effect of the maximum peripheral velocity W0 of the inflow jet, W = W(r) is calculated from the velocity 0 at the center O of the tubular space 20 (combustion tube base 21) to the velocity at the cylindrical inner wall of the combustion tube (radius R d ) to W0, the rigid body rotation speed distribution W=(r / R d ) × W0 (drawn at the bottom of Figures 14 and 15 for reference). In this case, G φ is expressed as follows:

[0056]

number

[0057] Furthermore, W0 = V0 × sin(Af°), and V0 = Q / (N × h × B) = (UπR d 2 ) / (N×h×B), G φ is expressed as follows:

[0058]

number

[0059] Therefore, the swirl number S can be calculated using the following formula:

[0060]

number

[0061] (2) Integrating only the tangential velocity component W0 of the inflowing jet. In this case, G φ is expressed as follows:

[0062]

number

[0063] Therefore, the inflow swirl number S' can be calculated by the following formula.

[0064]

number

[0065] In addition to the configuration described above, the burner 1 can also be configured to have a combustion tube tip 27, as exemplified in Fig. 3. The combustion tube tip 27 is connected to the other end of the tubular space 20 and is formed in a tubular shape. The other end of the tubular space 20 is the end opposite the end on the combustion tube base 21 side, of both ends of the tubular space 20. When the burner 1 has the combustion tube tip 27, the swirling flow formed in the tubular space 20 flows forward while swirling along the inner wall surface of the combustion tube tip 27, which makes it easier to stabilize the tubular flame.

[0066] The length of the combustion tube tip 27 is not particularly limited, but from the viewpoint of stabilizing the tubular flame, it is preferably at least 0.2 times the inner diameter of the tubular space 20, more preferably at least 0.3 times the inner diameter of the tubular space 20, and even more preferably at least 0.4 times the inner diameter of the tubular space 20. Furthermore, from the viewpoint of reducing the size of the burner 1, the length of the combustion tube tip 27 is preferably at most 4 times the inner diameter of the tubular space 20, more preferably at most 3 times the inner diameter of the tubular space 20, and even more preferably at most 2 times the inner diameter of the tubular space 20.

[0067] In addition to the above-mentioned configuration, the burner 1 can also be configured to have a turbulence generating section 28 at a position where it can turbulently generate turbulence in the gas flow ejected into the tubular space 20, as exemplified in Figures 16 to 19. With this configuration, the gas flow ejected into the tubular space 20 hits the turbulence generating section 28, generating turbulence in the gas flow and making it possible to turn the swirling flow into turbulence. Therefore, in this case, there are advantages such as shortening the flame that is formed, shortening the length of the burner 1, and promoting the mixing of the fuel and air A.

[0068] The configuration of the turbulence generating section 28 is not particularly limited as long as it can cause turbulence in the gas flow injected into the tubular space 20. The turbulence generating section 28 can be configured, for example, by a combination of uneven sections and various structures. For example, Fig. 15 shows an example of the arrangement of the swirl vanes 24 before the turbulence generating section 28 is attached, as seen from the front of the burner 1.

[0069] 16, a turbulent flow generating section 28 can be configured by providing a ring member 281 perpendicular to the burner central axis L and extending in the circumferential direction in a portion of the tubular space 20 near the outer periphery of the tubular space 20. Note that perpendicular to the burner central axis L does not only mean that the ring member intersects with the burner central axis L at a geometrically strict right angle, but also means that the ring member intersects with the burner central axis L at an angle inclined within a range of -15 degrees to 15 degrees with respect to the right angle.

[0070] 17 and 18, the turbulence generating section 28 can also be configured by forming a convex portion 282 that protrudes into the inter-blade flow passage 25 on a flat portion of the swirl vane 24. Note that in FIGS. 17 and 18, an example is shown in which the convex portion 282 is formed on a portion of the flat surface of the swirl vane 24 closer to the tubular space 20, from the viewpoint of efficiently turbulenting the gas flow ejected into the tubular space 20. The number of convex portions 282 is not particularly limited, and one or more convex portions 282 may be formed per inter-blade flow passage 25 (per swirl vane 24).

[0071] 19, the turbulent flow generating section 28 can also be configured by providing columnar members 283 parallel to the burner central axis L and circumferentially in areas of the tubular space 20 near the outer periphery of the tubular space 20 or at the tips of the inter-blade passages 25. Note that "parallel to the burner central axis L" does not only mean being geometrically strictly parallel to the burner central axis L, but also means being inclined at an angle within a range of -15 degrees to 15 degrees with respect to the burner central axis L.

[0072] As described above, the turbulence generating section 28 can be composed of a structural part (such as the ring member 281) that is perpendicular to the burner central axis L and in the circumferential direction, a structural part (such as the convex part 282) that is perpendicular to the burner central axis L and in the flow path width direction of the inter-blade flow path 25, a structural part (such as the columnar member 283) that is parallel to the burner central axis L, or a combination of these.

[0073] In addition to the above-described configuration, the burner 1 can be configured to have an observation window (not shown) on at least a portion of the peripheral wall of at least one of the combustion tube base 21 and the combustion tube tip 27 for observing the flame formed inside the burner 1. In this case, the flame formed inside the burner 1 can be observed from outside the burner 1 through the observation window. This is particularly useful when, for example, ammonia, a flame-retardant fuel, is used as the fuel, as it allows the combustion state to be easily confirmed. The observation window can be made of, for example, heat-resistant transparent glass.

[0074] (Experimental Example 1) A burner having a flat-plate-shaped swirl blade configured to be angle variable, as shown in Figures 7 to 11, was fabricated. Figure 21 shows the dimensions (unit: mm) of the fabricated burner. As shown in Figure 22, burner 1 is provided with a combustion tube base 21 including a bottom (thickness 8 mm, made of SUS303) and a quartz glass tube (inner diameter 62 mm, outer diameter 68 mm, length 40 mm) erected on the outer peripheral edge of the bottom, and a combustion tube tip 27 formed from the quartz glass tube (inner diameter 62 mm, outer diameter 68 mm, length 215 mm).

[0075] In this experimental example, a blower was connected so that air was supplied to the air inlet of the outer flow passage, and ammonia gas was supplied as the first fuel by the first fuel supply unit. The burner was designed so that the internal heating was barely performed until each gas was ejected into the tubular space, and a gas flow of premixed ammonia gas and air was ejected from the inter-blade flow passage into the tubular space, forming a swirling flow. Ignition was performed by intermittent discharge from a spark plug or ignition electrode only at the time of ignition. After ignition, the discharge was stopped, but a continuous flame was obtained thereafter.

[0076] Ammonia gas (purity 99.99%) is supplied from a cylinder to the burner via a pressure regulator and mass flow meter. Because the mass flow meter used (Kofloc Corporation, Model 3810DSII, for air, maximum flow rate 100NL / min., needle valve included) was for air, the material of the internal packing was changed from fluororubber to butyl rubber and nitrile rubber to protect against corrosion by ammonia, and the flow rate was also calibrated for ammonia gas before use.

[0077] In addition, air (standard air, room temperature, normal pressure, oxygen concentration 21.0%, non-preheated) was supplied through a rectifying inlet pipe and an ultrasonic flowmeter (Aichi Tokei Denki Co., Ltd., TRX65D-C / 5P, diameter 65A, maximum measured flow rate 240m 3 / h), blower (Makita, UB1103, power supply single phase 100V, current 6.3A, air volume 0-4.1m 3 / min., stepless speed control, power consumption 600W, dust collector air volume 0~4.1m 3 / min., vacuum level 0-5.7 kPa), is supplied to the air inlet of the outer flow path of the burner via an aluminum flexible pipe. A power supply with a voltage regulated to 20-30 V by a variac was supplied to the blower as the driving power source, so the actual power consumption is estimated to be approximately 24-54 W. Note that in this experimental example, for the purpose of the combustion test, the blower was connected so that the air was supplied to the air inlet of the outer flow path via an aluminum flexible pipe, but in an actual burner product, an air supply device such as a blower can be integrally connected to the air inlet of the outer flow path.

[0078] The design drawings of the small combustion furnace 9 fabricated for the combustion test of the burner are shown in Figures 22 and 23. As shown in Figures 22 and 23, the dimensions of the combustion furnace body 91 are 450 mm in length, with a flow path shape of 200 mm square, and the dimensions of the chimney section 92 are 300 mm in length and 60 mm square. The insulating wall material of both furnaces is biodegradable ceramic fiber board (25 mm thick, refractory temperature 1100°C). The chimney section 92 has a gas sampling port at a position determined based on JIS K0095 for measuring gas concentration using a gas concentration measuring instrument 93. In addition, a ceramic honeycomb 94 was installed upstream of the chimney section to rectify the flow near the sampling port.

[0079] In order to understand the combustion characteristics of the burner, mapping of the combustion state was created while changing the swirl number S, equivalence ratio φ, and fuel flow rate. The mapping of the combustion state for each swirl number is shown in Figures 24 to 32. In this disclosure, the supply calorific value of the supplied fuel is considered to be the amount of heat generated.

[0080] In each of these figures, the horizontal axis represents the equivalence ratio φ, and the vertical axis represents the axial mean flow velocity of the premixed gas in the tubular space. The combustion state was visually confirmed and classified into stable combustion (open circle symbol), unstable combustion (flame extinguished in a short time, filled circle symbol), and blow-off (× symbol). Unstable combustion is defined as a state in which the flame is extinguished in a short time after temporary flame stabilization. For the mapping, the air flow rate Q in the premixed gas was used. air When the air flow rate to be measured was large, the measurement was limited to the flow rate limit of the mass flow meter.

[0081] As shown in Figures 24 to 32, it was shown that combustion using a tubular flame was possible at any swirl number. This confirmed that the above burner can be operated even when using ammonia, a type of flame-retardant fuel, as fuel by supplying air from an air supply device with a supply pressure lower than that of a compressor.

[0082] The mappings shown in Figures 24 to 32 will be considered in more detail below. As shown in Figure 31, as the outlet passage width h of the inter-blade passage is narrowed and the swirl number S increases, the flame-stabilizing range tends to shift to the lean combustion side (left side). Also, assuming complete combustion of the fuel, the maximum heat release q [kcal / h, kW] at the outlet passage width h of the inter-blade passage (swirl number S, inflow swirl number S') in this measurement range is summarized in Table 1. Table 1 summarizes the specifications related to swirl strength and data on the maximum heat release for a burner with flat-plate swirl vanes configured to be angle-variable.

[0083] From the results shown in Figures 23 to 31, it can be said that it is preferable to set the swirl number S to 0.79 or more (the inflow swirl number S' to 0.49 or more). In this case, under conditions where the equivalence ratio is around 1.1, a heat generation amount of approximately 18,000 kcal / h (21 kW) can be achieved. When manufacturing the burner, it is sufficient to increase the inner diameter of the tubular space depending on the amount of heat generation required, but in order to ensure high flame stability, it is preferable to set the swirl number S to 4.5 or more (the inflow swirl number S' to 0.65 or more).

[0084] Furthermore, Figures 33 and 34 show the nitrogen oxide emission concentrations (O2 12% equivalent) measured in the burner systems shown in Figures 21 to 23 at an air flow rate of 160 L / min. The horizontal axis in these figures represents the equivalence ratio φ. As shown in Figures 22 and 23, both measurements were performed by inserting the tip of the gas concentration measuring instrument 93 into the chimney 92 and sucking in the combustion exhaust gas. The values ​​of 1 mm, 2 mm, 3 mm, and 4 mm in Figures 33 and 34 represent the outlet flow path width h of the inter-blade flow path, and the various swirl numbers at that time are as follows, as shown in Table 1. h=1mm (swirl number S=4.5, inflow swirl number S'=0.65) h=2mm (swirl number S=2.2, inflow swirl number S'=0.62) h=3mm (swirl number S=1.4, inflow swirl number S'=0.58) h=4mm (swirl number S=1.0, inflow swirl number S'=0.54)

[0085] Looking at the NO concentration in Figure 33 and the NO2 concentration in Figure 34, we can see that for h = 2 mm, 3 mm, and 4 mm, the NO and NO2 emission concentrations are highest at an equivalence ratio of 1.2, and tend to decrease as the equivalence ratio decreases. Furthermore, under the condition of high swirl strength (h = 1 mm), the emission concentration is highest at an equivalence ratio of 1.0, but is low at an equivalence ratio of 1.2. At an equivalence ratio of 1.5, the NO concentration is around 200 ppm, suggesting that an ammonia-fired low-NOx burner that meets the regulatory limit can be realized. Furthermore, since the emission concentration tends to decrease sharply as the equivalence ratio increases from 1.0 to 0.9, it can be said that by improving the flame stability and combustion characteristics of the burner disclosed herein, combustion can be performed under leaner fuel conditions (e.g., an equivalence ratio of 0.8 in Figures 33 and 34), a burner with low nitrogen oxide emissions that meets emission standards can be realized.

[0086] [Table 1]

[0087] (Experimental Example 2) In order to create a more uniform swirling flow than the burner with flat-shaped swirl vanes shown in Figures 7 to 11 (Figure 14), we fabricated a burner with swirl vanes shown in Figure 15, in which the swirl vanes were curved to improve the flow velocity as the flow path was narrowed. The outlet flow path width of the inter-blade flow path was h = 2.36 mm, the swirl number S = 1.9, and the inlet swirl number S' = 0.56. As in Experimental Example 1, this burner was connected to a small combustion furnace 9 as shown in Figure 22, and a premixed gas of air (standard air, room temperature, normal pressure, oxygen concentration 21.0%) and fuel (100% ammonia, room temperature) at an air flow rate of 160 L / min was supplied from the inter-blade flow path to the tubular space, and the combustion exhaust gas components were measured.

[0088] Figures 35 and 36 show the measurement results for NO and NO2 concentrations, respectively. The NO and NO2 concentrations reached their maximums at an equivalence ratio of 1.1. This is equivalent to the maximum peaks at equivalence ratios of 1.0 to 1.2 in the flat-plate swirl impeller data (Figures 33 and 34). On the other hand, Figures 35 and 36 show that extremely low NO and NO2 concentrations (below 180 ppm) were obtained at equivalence ratios of 0.9 and 1.0, which are leaner fuel mixtures. These results confirm that by forming a more uniform swirl flow, it is possible to realize an unprecedented ammonia-fired low-NOx burner that uses only normal air and ammonia without preheating.

[0089] The present invention is not limited to the above-described embodiments and experimental examples, and various modifications are possible within the scope of the gist thereof. Furthermore, the configurations shown in the above-described embodiments and experimental examples can be combined in any manner. Furthermore, the claims set forth in the scope of the claims as originally filed can be combined in any manner.

[0090] The features of the present invention are as follows. Section 1. a tubular space provided in the center of the burner; a combustion tube base portion having a bottom and a tubular shape, the combustion tube base portion being connected to one end of the tubular space; an inner flow path provided on the outer periphery of the tubular space; an outer flow path that is in communication with the inner flow path and is provided on an outer periphery of the inner flow path, and to which air sent from an air supply device is supplied; a plurality of swirl vanes for forming a swirl flow provided between the inner flow path and the tubular space so as to surround an outer periphery of the tubular space; an inter-blade flow passage formed between each adjacent one of the swirl vanes and communicating the inner flow passage with the tubular space; a fuel supply unit including at least one selected from the group consisting of a first fuel supply unit capable of supplying a first fuel into the outer flow passage, a second fuel supply unit capable of supplying a second fuel into the combustion tube base, and a third fuel supply unit capable of supplying a third fuel into the inter-blade flow passage or the tubular space, a gas flow passing through the inter-blade passage and ejected into the tubular space forms a swirling flow in the tubular space; Burner. Section 2. a tubular combustion tube tip portion connected to the other end of the tubular space; Item 1. The burner according to item 1. Section 3. The inner flow path and the outer flow path are configured to be able to communicate with each other via a plate member having a large number of through holes formed therein. Item 1 or 2. The burner according to item 1 or 2. Section 4. The second fuel supply unit is configured to be able to supply the second fuel from a center part of a bottom part of the combustion tube base in a direction inclined with respect to the axial direction of the tubular space. Item 1 to Item 3: A burner according to any one of items 1 to 3. Section 5. the second fuel supply section is configured to be able to supply the second fuel from a center part of a bottom part of the combustion tube base section in a direction inclined with respect to the axial direction of the tubular space and in a direction reinforcing the swirling flow. Item 1 to Item 4: A burner according to any one of items 1 to 4. Section 6. The swirl number S of the swirling flow can be set to 0.79 or more. Item 6. The burner according to any one of items 1 to 5. Section 7. The air supply device is integrally connected to an air inlet formed at one end of the outer flow path. Item 7. The burner according to any one of items 1 to 6. Section 8. The swirl vanes are configured to be angle variable, By varying the angle of the swirl vanes, the cross-sectional area of ​​the inter-blade flow passage and the ejection direction of the gas flow ejected into the tubular space can be varied, thereby making it possible to vary the swirl number of the swirling flow. Item 8. The burner according to any one of items 1 to 7. Section 9. The swirl vanes are configured to be angle variable, The angle of the plurality of swirl vanes can be simultaneously varied by changing the angle of a lever provided outside the outer flow path. Item 9. The burner according to any one of items 1 to 8. Section 10. a turbulence generating portion disposed at a position capable of generating turbulence in the gas flow ejected into the tubular space; Item 10. The burner according to any one of items 1 to 9. Section 11. a tubular combustion tube tip portion connected to the other end of the tubular space, an observation window portion for observing a flame formed inside the burner is provided in at least a part of a peripheral wall of at least one of the combustion tube base portion and the combustion tube tip portion; Item 11. The burner according to any one of items 1 to 10. [Explanation of symbols]

[0091] 1 Burner 20 tubular space 21 Combustion tube base 22 Inner flow path 23 Outer channel 24 Swirl blades 25 Blade passage 26 Fuel supply section 261 1st fuel supply section 261 1st fuel supply section 262 2nd fuel supply section 263 3rd fuel supply section 9. Air supply device A. Air F1 No. 1 fuel F2 Second Fuel F3 Third Fuel

Claims

1. a tubular space provided in the center of the burner; a combustion tube base portion having a bottom and a tubular shape, the combustion tube base portion being connected to one end of the tubular space; an inner flow path provided along the outer periphery of the tubular space; an outer flow path that is in communication with the inner flow path and is provided on an outer periphery of the inner flow path, and to which air sent from an air supply device is supplied; a plurality of swirl vanes for forming a swirl flow provided between the inner flow path and the tubular space so as to surround an outer periphery of the tubular space; an inter-blade flow passage formed between each adjacent one of the swirl vanes and communicating the inner flow passage with the tubular space; a fuel supply unit including at least one selected from the group consisting of a first fuel supply unit capable of supplying a first fuel into the outer flow passage, a second fuel supply unit capable of supplying a second fuel into the combustion tube base, and a third fuel supply unit capable of supplying a third fuel into the inter-blade flow passage or the tubular space, the inter-blade flow passage is defined by inner surfaces of the adjacent swirl vanes on the flow passage side, a burner rear cover provided on the combustion tube base side, and a burner front cover provided on the opposite side to the combustion tube base side, a gas flow passing through the inter-blade passage and ejected into the tubular space forms a swirling flow in the tubular space; Burner.

2. a tubular combustion tube tip portion connected to the other end of the tubular space; 2. The burner of claim 1.

3. The inner flow path and the outer flow path are configured to be able to communicate with each other via a plate member having a large number of through holes formed therein.

2. The burner of claim 1.

4. the second fuel supply unit is configured to be able to supply the second fuel from a center of a bottom of the combustion tube base in a direction inclined with respect to the axial direction of the tubular space.

2. The burner of claim 1.

5. the second fuel supply section is configured to be able to supply the second fuel from a center part of a bottom of the combustion tube base in a direction inclined with respect to a tube axis direction of the tubular space and in a direction reinforcing the swirling flow.

2. The burner of claim 1.

6. The swirl number S of the swirling flow can be set to 0.79 or more.

2. The burner of claim 1.

7. The air supply device is integrally connected to an air inlet formed at one end of the outer flow path.

2. The burner of claim 1.

8. The swirl vanes are configured to be angle variable, By varying the angle of the swirl vanes, the cross-sectional area of ​​the inter-blade flow passage and the ejection direction of the gas flow ejected into the tubular space can be varied, thereby making it possible to vary the swirl number of the swirling flow.

2. The burner of claim 1.

9. The swirl vanes are configured to be angle variable, The angle of the plurality of swirl vanes can be simultaneously varied by changing the angle of a lever provided outside the outer flow path.

2. The burner of claim 1.

10. a turbulence generating portion disposed at a position capable of generating turbulence in the gas flow ejected into the tubular space; 2. The burner of claim 1.

11. a tubular combustion tube tip portion connected to the other end of the tubular space, an observation window portion for observing a flame formed inside the burner is provided in at least a part of a peripheral wall of at least one of the combustion tube base portion and the combustion tube tip portion; 2. The burner of claim 1.

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