Duct burner and gas turbine system

Abstract

This duct burner is disposed in an exhaust-gas flow path through which exhaust gas discharged from a gas turbine flows, and comprises: at least one nozzle for jetting gas fuel into the exhaust-gas flow path; and a flame stabilizer that includes a pair of plate members that are situated opposing each other sandwiching the nozzle and, heading downstream in the exhaust-gas flow path, separate from the center axis of the nozzle. The nozzle includes: at least one auxiliary hole configured to jet gas fuel along a flame-stabilizing surface of the plate member downstream in the exhaust-gas flow path; and at least one main hole that is diametrically larger than the auxiliary hole and is configured to jet gas fuel inclined more to the nozzle center-axis side than the auxiliary hole.

Description

Duct burner and gas turbine system

[0001] This disclosure relates to a duct burner and a gas turbine system including the duct burner. This application claims priority to Japanese Patent Application No. 2023-137752, filed with the Japan Patent Office on August 28, 2023, the contents of which are incorporated herein by reference.

[0002] For example, as disclosed in Non-Patent Document 1, in a gas turbine cogeneration system equipped with a gas turbine and a heat recovery boiler, a duct burner is sometimes provided upstream of the heat recovery boiler to increase the amount of heat recovered by the heat recovery boiler. The duct burner injects fuel into the exhaust gas discharged from the gas turbine and performs combustion heating using the oxygen contained in the exhaust gas.

[0003] IHI Technical Report VOL. 49 No. 2 (2009-6) P103-P107

[0004] However, when the oxygen concentration in the exhaust gas is low, it is not easy to achieve stable combustion with the duct burner.

[0005] The present disclosure has been made in consideration of the above-mentioned problems, and aims to provide a duct burner that can perform stable combustion.

[0006] In order to achieve the above-mentioned object, the duct burner of the present disclosure is a duct burner that is arranged in an exhaust gas flow path through which exhaust gas discharged from a gas turbine flows, and comprises at least one nozzle that injects gas fuel into the exhaust gas flow path, and a flame stabilizer that includes a pair of plate-shaped members that are located on opposite sides of the nozzle and that move away from the central axis of the nozzle as they move toward the downstream side of the exhaust gas flow path, and the nozzle includes at least one sub-hole configured to inject the gas fuel along the flame-stabilizing surface of the plate-shaped member on the downstream side of the exhaust gas flow path, and at least one main hole that is larger in diameter than the sub-hole and configured to inject the gas fuel at an angle closer to the central axis of the nozzle than the sub-hole.

[0007] The duct burner of the present disclosure can achieve stable combustion.

[0008] FIG. 4 is a diagram showing a schematic configuration of a gas turbine system equipped with a duct burner according to an embodiment. FIG. 5 is a diagram showing a schematic configuration of a nozzle according to an embodiment. FIG. 6 is a side cross-sectional view of a nozzle according to an embodiment (view taken along the arrows A-A in FIG. 4). FIG. 7 is a diagram showing a schematic configuration of a nozzle according to an embodiment. FIG. 8 is a diagram showing a schematic configuration of an ignition nozzle according to an embodiment. FIG. 9 is a diagram showing a schematic configuration of a left nozzle and a right nozzle according to an embodiment. FIG. 10 is a diagram showing a schematic configuration of a nozzle according to some embodiments. FIG. 11 is a diagram showing whether stable combustion has been achieved in a duct burner according to an embodiment. FIG. 12 is a diagram showing whether stable combustion has been achieved in a duct burner according to another embodiment.

[0009] Hereinafter, a duct burner according to an embodiment of the present disclosure will be described with reference to the drawings. The embodiment shows one aspect of the present disclosure, but does not limit the present disclosure and can be modified as desired within the scope of the technical concept of the present disclosure.

[0010] <Gas Turbine> Fig. 1 is a diagram that shows a schematic configuration of a gas turbine system 100 that includes a duct burner 1 according to some embodiments. As shown in Fig. 1, the gas turbine system 100 includes a gas turbine 110, an exhaust gas flow path 120 through which exhaust gas G discharged from the gas turbine 110 flows, a waste heat recovery steam generator 130 that is arranged in the exhaust gas flow path 120, and a duct burner 1 according to some embodiments.

[0011] The gas turbine 110 includes a compressor 112, a combustor 114, and a turbine 116. The compressor 112 compresses air A1 supplied from an external source to generate compressed air A2. The combustor 114 injects fuel A3 into the compressed air A2 generated by the compressor 112 and burns the fuel to generate combustion gas A4. The fuel A3 is, but is not limited to, hydrogen gas. In some embodiments, the fuel A3 is a hydrocarbon gas such as LPG or LNG.

[0012] The turbine 116 is rotationally driven by the passage of the combustion gas A4 generated by the combustor 114, and converts thermal energy of the combustion gas A4 into rotational energy. The turbine 116 is connected to the compressor 112 via a rotary shaft 113, and transmits the rotational energy to the compressor 112. The compressor 112 is driven by the rotational energy of the turbine 116. In the embodiment illustrated in Fig. 1 , the gas turbine system 100 further includes a generator 140 connected to the rotary shaft 113. The generator 140 generates electric power by using the rotational energy of the turbine 116.

[0013] The exhaust gas flow path 120 is defined by an inner wall surface 124 of a cylindrical duct 122 (see FIG. 2 ). The exhaust heat recovery boiler 130 generates steam by heating feedwater using thermal energy contained in the exhaust gas G. The destination of the exhaust gas G that has passed through the exhaust heat recovery boiler 130 is not particularly limited, but may be, for example, a CO2 absorption tower that absorbs CO2 from the exhaust gas G into an absorption liquid.

[0014] <Duct Burner> (Configuration) The duct burner 1 is disposed upstream of the heat recovery boiler 130 in the exhaust gas flow path 120. Fig. 2 is a diagram schematically showing the configuration of the duct burner 1 according to one embodiment, and is a diagram (front view) of the duct burner 1 as viewed from the downstream side of the exhaust gas flow path 120.

[0015] In one embodiment, as shown in Fig. 2, the duct burner 1 includes a plurality of fuel supply pipes 2 extending in the left-right direction D1 through the exhaust gas flow path 120. The plurality of fuel supply pipes 2 are arranged at intervals from one another in the up-down direction D2. Each of the plurality of fuel supply pipes 2 has a cylindrical shape, and gas fuel F supplied from a supply source (not shown) flows through the interior of the plurality of fuel supply pipes 2. The gas fuel F is not particularly limited, but is preferably hydrogen gas. The gas fuel F may also be a hydrocarbon gas such as LPG or LNG.

[0016] The duct burner 1 includes a nozzle 4 connected to a fuel supply pipe 2 and ejecting gas fuel F into an exhaust gas flow path 120, and a flame stabilizer 6 having a pair of plate-like members 8A, 8B positioned on opposite sides of the nozzle 4. In one embodiment, as shown in Fig. 2, a plurality of nozzles 4 are provided on one fuel supply pipe 2 lined up along the left-right direction D1 (a manifold is formed).

[0017] The pair of plate-shaped members 8A, 8B are arranged along the up-down direction D2 and include an upper plate-shaped member 8A and a lower plate-shaped member 8B positioned below the upper plate-shaped member 8A. The upper plate-shaped member 8A and the lower plate-shaped member 8B are connected to a common nozzle 4. The upper plate-shaped member 8A and the lower plate-shaped member 8B are arranged so that at least a portion of them overlap each other in the left-right direction D1 when viewed from the front.

[0018] 2, multiple nozzles 4 are arranged side by side in the left-right direction D1 on one fuel supply pipe 2, but the present disclosure is not limited to this. The duct burner 1 may also include a fuel supply pipe 2 extending along the up-down direction D2 and multiple nozzles 4 arranged side by side in the up-down direction D2 on the fuel supply pipe 2. In this case, the pair of plate-like members 8A, 8B are arranged on opposite sides of the nozzle 4 in the left-right direction D1.

[0019] In one embodiment, as shown in FIG. 2 , the duct burner 1 further includes an ignition device 30 that ignites the gaseous fuel F. The ignition device 30 is provided in the duct 122 and is located downstream of the nozzle 4 in the exhaust gas flow path 120. The ignition device 30 may be configured to ignite the gaseous fuel F. For example, the ignition device 30 may employ pilot ignition, which ignites the gaseous fuel F using a flame formed by a small burner, or direct ignition, which ignites the gaseous fuel F by spark discharge from an ignition plug. An ignition device 30 may be provided for each fuel supply pipe 2. Of the multiple nozzles 4 provided in one fuel supply pipe 2, the nozzle 4 located closest to the ignition device 30 is the ignition nozzle 20(4). The multiple nozzles 4 provided in one fuel supply pipe 2 include a left nozzle 40(4) and a right nozzle 42(4) adjacent to the left nozzle 40 on the right. The configurations of the ignition nozzle 20, the left nozzle 40, and the right nozzle 42 will be described later.

[0020] Figure 3 is a side cross-sectional view of a nozzle 4 according to one embodiment. As shown in Figure 3, the nozzle 4 includes a main hole 10 and a sub-hole 12. The sub-hole 12 is configured to inject the gas fuel F along a flame-holding surface 14 downstream of the exhaust gas flow path 120 of the upper plate-shaped member 8A or the lower plate-shaped member 8B. The main hole 10 has a larger diameter than the sub-hole 12. The main hole 10 is configured to inject the gas fuel F at an angle inclined toward the central axis O of the nozzle 4 relative to the sub-hole 12.

[0021] A specific configuration example of the main hole 10 and the sub-hole 12 according to one embodiment will be described. The main hole 10 and the sub-hole 12 each extend linearly. The angle formed by an imaginary first line L1 extending in the ejection direction of the main hole 10 and the central axis O of the nozzle 4 is defined as the main-hole ejection angle θ1. The angle formed by an imaginary second line L2 extending in the ejection direction of the sub-hole 12 and the central axis O of the nozzle 4 is defined as the sub-hole ejection angle θ2. The main-hole ejection angle θ1 is equal to or greater than 20 degrees and less than 40 degrees. The sub-hole ejection angle θ2 is equal to or greater than 40 degrees and less than 50 degrees.

[0022] As shown in Figure 3, the upper plate member 8A and the lower plate member 8B each move away from the central axis O of the nozzle 4 as they move downstream in the exhaust gas flow path 120. The upper plate member 8A and the lower plate member 8B are each symmetrical with respect to the central axis O of the nozzle. The upper plate member 8A and the lower plate member 8B are each configured so that the angle θ3 of the flame stabilizing surface 14 with respect to the central axis O of the nozzle 4 is between 40 degrees and 50 degrees. In one embodiment, the angle θ3 of the flame stabilizing surface 14 is 45 degrees. The angle θ3 of the flame stabilizing surface 14 is the same angle as the sub-hole jet angle θ2.

[0023] Each of the upper plate-shaped member 8A and the lower plate-shaped member 8B has a plurality of through holes 18 formed therein, extending from the flame stabilizing surface 14 to the surface 16 opposite the flame stabilizing surface 14. If the ratio of the area of ​​the plurality of through holes 18 to the area of ​​the flame stabilizing surface 14, including the area of ​​the plurality of through holes 18, is taken as the aperture ratio, the aperture ratio is 20% or more and 50% or less. The number of through holes 18 is not particularly limited, and may be one, or two or more.

[0024] FIG. 4 is a diagram schematically illustrating the configuration of a nozzle 4 according to an embodiment, and is a diagram (front view) of the nozzle 4 as viewed from the downstream side of the exhaust gas flow path 120. In one embodiment, as shown in FIG. 4 , the nozzle 4 is formed with four main holes 10 and four sub-holes 12. The four main holes 10 are arranged symmetrically around the central axis O of the nozzle 4 with respect to the central axis O of the nozzle. The four sub-holes 12 are arranged symmetrically around the central axis O of the nozzle 4 with respect to the central axis O of the nozzle. The four main holes 10 and the four sub-holes 12 are arranged alternately and evenly around the central axis O of the nozzle 4. In other words, they are spaced apart by an equal pitch angle α of 45 degrees around the central axis O of the nozzle 4. In a front view, the center position 10a of the opening of the main hole 10 and the center position 12a of the opening of the sub-hole 12 are the same distance from the central axis O of the nozzle 4. Furthermore, the cross-sectional shapes of the main holes 10 and the sub-holes 12 are circular.

[0025] FIG. 5 is a schematic diagram illustrating the configuration of an ignition nozzle 20 according to one embodiment. As shown in FIG. 5 , the ignition nozzle 20 is formed with a small-diameter hole 21 configured to eject gas fuel F closer to the central axis O of the nozzle 4 than the four main holes 10 and the four sub-holes 12. The small-diameter hole 21 has a smaller diameter than each of the four sub-holes 12. In the configuration illustrated in FIG. 5 , the small-diameter hole 21 extends linearly along the central axis O of the nozzle 4. The small-diameter hole 21 is located radially inward of the four main holes 10 and the four sub-holes 12. The small-diameter hole 21 is formed in a tip surface 23 of the ignition nozzle 20. The main hole 10 and the sub-holes 12 are each formed in an extension surface 27 extending from the tip surface 23 of the ignition nozzle 20 to a side surface 25. In some embodiments, if the angle formed by an imaginary line extending in the ejection direction of the small diameter hole 21 and the central axis O of the nozzle 4 is defined as the small diameter hole ejection angle, this small diameter hole ejection angle is smaller than both the main hole ejection angle θ1 and the sub-hole ejection angle θ2. Note that the nozzle 4 illustrated in Figure 3 also has the main hole 10 and the sub-hole 12 formed on the extension surface.

[0026] Figure 6 is a diagram schematically showing the configuration of the left nozzle 40(4) and the right nozzle 42(4) according to one embodiment. As shown in Figure 6, when the duct burner 1 is viewed from the downstream side of the exhaust gas flow path 120, the angular position θ of an imaginary line L3 extending upward from the central axis O of the nozzle 4 is defined as 0 degrees. This angular position θ increases as the nozzle 4 rotates clockwise around the central axis O as the center of rotation, and the angular position θ when the imaginary line L3 makes one rotation is defined as 360 degrees.

[0027] 6 , each of the left nozzle 40 and the right nozzle 42 includes an upper sub-hole 44 (12) of the multiple sub-holes 12 whose angular position θ is between 0 and 10 degrees, or between 350 and 360 degrees, and a lower sub-hole 46 (12) whose angular position θ is between 170 and 190 degrees. The left nozzle 40 includes a right sub-hole 48 (12) whose angular position θ is between 80 and 100 degrees. The right nozzle 42 includes a left sub-hole 50 (12) whose angular position θ is between 260 and 280 degrees.

[0028] FIG. 7 is a diagram schematically illustrating the configuration of a nozzle 4 according to some embodiments. In the configuration illustrated in FIG. 7 , the nozzle 4 includes a second sub-hole 54 in addition to the main hole 10 and the sub-hole 12. The second sub-hole 54 includes a right-side second sub-hole 54A (54) whose angular position θ is between 80 degrees and 100 degrees, and a left-side second sub-hole 54B (54) whose angular position θ is between 260 degrees and 280 degrees. The second sub-hole 54 is configured to eject the gas fuel F at an ejection angle between 50 degrees and 90 degrees with respect to the central axis O of the nozzle 4. In other words, since the pair of plate-shaped members 8A, 8B are not disposed in the left-right direction D1 of the nozzle 4, the second sub-hole 54 is not configured to eject the gas fuel F along the flame-stabilizing surface 14, but rather prioritizes improving the flame-stabilizing effect. The ejection angle of the second sub-hole 54 is greater than the sub-hole ejection angle θ2. The second sub-hole 54 may have the same diameter as the sub-hole 12 or may have a diameter different from that of the sub-hole 12 .

[0029] 7, the second sub-hole 54 has a larger ejection angle than the right sub-hole 48 and the left sub-hole 50 illustrated in FIG. 6. In other words, the gas fuel F ejected from the second sub-hole 54 can reach the adjacent nozzle 4 in a shorter distance than the gas fuel F ejected from the right sub-hole 48 or the left sub-hole 50. Therefore, a nozzle 4 equipped with the second sub-hole 54 can quickly ignite the nozzle 4 adjacent to it.

[0030] (Actions and Effects) The actions and effects of the duct burner 1 according to one embodiment will be described. Fig. 8 is a graph showing whether stable combustion has been achieved by the duct burner 1 according to one embodiment, with the oxygen concentration of the exhaust gas G on the horizontal axis and the temperature of the exhaust gas G on the vertical axis. Stable combustion by the duct burner 1 is a state in which the duct burner 1 forms a flame by burning the gas fuel F. The oxygen concentration of the exhaust gas G is the concentration of oxygen contained in the exhaust gas G flowing into the duct burner 1. The temperature of the exhaust gas G is the temperature of the exhaust gas G flowing into the duct burner 1.

[0031] In Figure 8, the dots marked with a black circle indicate stable combustion in the duct burner 1 according to one embodiment, the dots marked with a circle indicate stable combustion in the duct burner equipped with a conventional nozzle, and the dots marked with an x ​​indicate unstable combustion in the duct burner equipped with a conventional nozzle. The conventional nozzle is a nozzle in which only multiple main holes with equal ejection angles are formed, and no sub-holes are formed. Furthermore, the duct burner equipped with a conventional nozzle does not have a flame-holding mechanism installed in the nozzle, so the nozzle base is blown off and the flame is held near the flame holder of the duct burner.

[0032] The oxygen concentration and temperature of the exhaust gas G are the main factors determining whether the duct burner 1 achieves stable combustion. When the oxygen concentration of the exhaust gas G is low, the combustion of the duct burner 1 becomes unstable. Similarly, when the temperature of the exhaust gas G is low, the combustion of the duct burner 1 becomes unstable. As shown in FIG. 8 , the duct burner 1 according to one embodiment can achieve stable combustion even when the temperature of the exhaust gas G is 300°C, as long as the oxygen concentration of the exhaust gas G is 7% or higher. On the other hand, the conventional duct burner 1 cannot achieve stable combustion when the oxygen concentration of the exhaust gas G is 8% or 11% and the temperature of the exhaust gas G is 300°C. In the conventional duct burner 1, stable combustion at an oxygen concentration of the exhaust gas G of 8% or 11% requires the temperature of the exhaust gas G to be higher than 300°C. As shown in FIG. 8 , the stable combustion boundary B1 of the duct burner 1 according to one embodiment is lower than the stable combustion boundary B2 of the conventional duct burner in the low-oxygen region (14% or less). Therefore, the duct burner 1 according to one embodiment can broaden the conditions under which stable combustion is possible, compared to conventional duct burners 1 .

[0033] The duct burner 1 may have difficulty in achieving stable combustion due to the low oxygen concentration contained in the exhaust gas G. According to one embodiment, the sub-holes 12 eject the gaseous fuel F along the flame-stabilizing surface 14, thereby promoting mixing of the gaseous fuel F and the exhaust gas G in the region C1 (see FIG. 3 ) near where the gaseous fuel F is ejected from the nozzle 4, thereby suppressing flame fluctuation and strengthening flame stabilization. Furthermore, the main hole 10 ejects the gaseous fuel F at an angle closer to the central axis O of the nozzle than the sub-holes 12, thereby promoting slow combustion by lengthening the flame. Furthermore, the generation of nitrogen oxides (NOx) can be suppressed. This allows the duct burner 1 to achieve stable combustion.

[0034] According to one embodiment, by setting the ejection angle θ1 of the main hole 10 (the angle of elevation relative to the central axis O of the nozzle 4) to 40 degrees or less, slow combustion due to flame length can be promoted. On the other hand, if the ejection angle θ1 of the main hole 10 is less than 20 degrees, the flame length becomes excessively long, which may affect the heat absorption characteristics of the heat recovery boiler 130 that supplies the exhaust gas G heated by the duct burner 1. Furthermore, by setting the ejection angle θ2 of the sub-hole 12 to 40 degrees or more, the gas fuel F is combusted from the base of the tip of the nozzle 4, and the nozzle 4 can have a high flame-stabilizing effect. Furthermore, if the ejection angle θ2 of the sub-hole 12 is set to 50 degrees or more, the sub-hole flame formed by the combustion of the gas fuel F ejected from the sub-hole 12 may come into contact with the flame-stabilizing surface 14, which may reduce the durability of the flame stabilizer 6. On the other hand, if the ejection angle θ2 of the sub-hole 12 is set to less than 40 degrees, the sub-hole flame will move away from the flame stabilizer 6, thereby reducing the flame-stabilizing effect. Therefore, by setting the ejection angle θ1 of the main hole 10 to be equal to or greater than 20 degrees and equal to or less than 40 degrees, and the ejection angle θ2 of the sub-hole 12 to be equal to or greater than 40 degrees and less than 50 degrees, stable combustion in the duct burner 1 can be achieved. Note that the angle θ3 of the flame-stabilizing surface 14 is often set to 45 degrees. Therefore, by configuring the ejection angle θ2 of the sub-hole 12 to be equal to or greater than 40 degrees and less than 50 degrees, the duct burner 1 can ensure a certain level of flame-stabilizing effect while suppressing a decrease in the durability of the flame stabilizer 6.

[0035] According to one embodiment, the upper plate member 8A and the lower plate member 8B each have a through hole 18, which makes it possible to adjust the amount of exhaust gas G supplied to the vicinity of the point where the gas fuel F is ejected from the nozzle 4. If the aperture ratio is less than 20%, the amount of exhaust gas G passing through the through hole 18 is small, and the amount of exhaust gas G required to cool the flame stabilizer 6 is insufficient, which may cause the flame stabilizer 6 to become red-hot. If the aperture ratio exceeds 50%, there is a risk that the flame stabilization effect may be reduced depending on the type of gas fuel F. Therefore, according to one embodiment, the aperture ratio is 20% or more and 50% or less, which makes it possible to suitably suppress the generation of NOx.

[0036] According to one embodiment, the ignition nozzle 20 is formed with small-diameter holes 21 that eject the gas fuel F closer to the central axis O of the nozzle 4 than the four main holes 10 and the four sub-holes 12. This expands the area C2 (see FIG. 5 ) where the gas fuel F ignites and burns when the duct burner 1 is started, thereby improving the ignition performance of the duct burner 1.

[0037] According to one embodiment, the ignition nozzle 20 is disposed closest to the ignition device 30 among the multiple nozzles 4. Therefore, the ignition performance of the duct burner 1 can be improved without making all or most of the multiple nozzles 4 ignition nozzles 20. The duct burner 1 may be provided with multiple ignition nozzles 20. The ignition nozzle 20 may be any nozzle 4 other than the nozzle 4 closest to the ignition device 30 among the multiple nozzles 4.

[0038] According to one embodiment, the four main holes 10 and the four sub-holes 12 are arranged alternately around the central axis O of the nozzle 4. Therefore, the gas fuel F is ejected uniformly from the four main holes 10 without bias with respect to the central axis O of the nozzle 4, and is also ejected uniformly from the four sub-holes 12 without bias with respect to the central axis O of the nozzle 4. Therefore, slow combustion due to the long flame can be smoothly continued.

[0039] The exhaust gas G passes through the through holes 18 formed in each of the upper plate member 8A and the lower plate member 8B and is supplied to a region C1 near where the gas fuel F is ejected from the nozzle 4. In other words, the exhaust gas G is supplied from above or below the nozzle 4. According to one embodiment, the left nozzle 40 and the right nozzle 42 each include an upper sub-hole 44 and a lower sub-hole 46, so that the gas fuel F ejected from the upper sub-hole 44 or the lower sub-hole 46 can be quickly mixed with the exhaust gas G.

[0040] According to one embodiment, the left nozzle 40 includes a right sub-hole 48, and the right nozzle 42 includes a left sub-hole 50, so that the left nozzle 40 can ignite the right nozzle 42, or the right nozzle 42 can ignite the left nozzle 40. Note that if the diameter of the right sub-hole 48 or the left sub-hole 50 were made as large as, for example, the diameter of the main hole 10, the flames of the left nozzle 40 and the right nozzle 42 would come into contact with each other, causing a temperature rise and the generation of NOx. For this reason, it is desirable that the sub-holes 12 be open in the left-right direction D1.

[0041] In one embodiment, the gas fuel F is hydrogen, but the present disclosure is not limited to this embodiment. In another embodiment, the gas fuel F is LPG. Fig. 9 is a graph showing whether stable combustion was performed in the duct burner 1 according to another embodiment, with the oxygen concentration of the exhaust gas G on the horizontal axis and the temperature of the exhaust gas G on the vertical axis.

[0042] In Fig. 9, the dots marked with a black circle indicate that stable combustion was achieved with the duct burner 1 according to another embodiment, and the dots marked with a plus sign indicate that stable combustion was achieved with the duct burner 1 according to another embodiment. Similarly, the dots marked with a circle indicate that stable combustion was achieved with the duct burner equipped with a conventional nozzle, and the dots marked with an x ​​indicate that stable combustion was not achieved with the duct burner equipped with a conventional nozzle.

[0043] As shown in FIG. 9 , the duct burner 1 according to another embodiment can perform stable combustion even when the temperature of the exhaust gas G is 400°C if the oxygen concentration of the exhaust gas G is 12%. On the other hand, the conventional duct burner 1 cannot perform stable combustion when the oxygen concentration of the exhaust gas G is 12% and the temperature of the exhaust gas G is 400°C. In the conventional duct burner 1, stable combustion when the oxygen concentration of the exhaust gas G is 10% requires the temperature of the exhaust gas G to be higher than 400°C (approximately 650°C). As shown in FIG. 9 , the stable combustion boundary B3 of the duct burner 1 according to another embodiment is lower than the stable combustion boundary B4 of the conventional duct burner in the low-oxygen region (14% or less). Therefore, the duct burner 1 according to another embodiment can broaden the conditions under which stable combustion is possible compared to the conventional duct burner 1.

[0044] The contents described in each of the above embodiments can be understood, for example, as follows.

[0045] [1] A duct burner (1) according to the present disclosure is a duct burner arranged in an exhaust gas flow path (120) through which exhaust gas (G) discharged from a gas turbine (110) flows, and comprises: at least one nozzle (4) that injects gas fuel (F) into the exhaust gas flow path; and a flame stabilizer (6) including a pair of plate-shaped members (8A, 8B) located on opposite sides of the nozzle and moving away from a central axis (O) of the nozzle as they move toward the downstream side of the exhaust gas flow path, wherein the nozzle includes at least one sub-hole (12) configured to inject the gas fuel along a flame-stabilizing surface (14) of the plate-shaped member on the downstream side of the exhaust gas flow path; and at least one main hole (10) having a diameter larger than the sub-hole and configured to inject the gas fuel at an angle closer to the central axis of the nozzle than the sub-hole.

[0046] Duct burners can have difficulty in achieving stable combustion due to the low oxygen concentration in exhaust gas. According to the configuration described in [1] above, the sub-holes eject gas fuel along the flame-stabilizing surface, which promotes mixing of the gas fuel and exhaust gas near where the gas fuel is ejected from the nozzle, suppressing flame fluctuations and strengthening flame stabilization. Furthermore, the main hole ejects gas fuel at an angle closer to the central axis of the nozzle than the sub-holes, which promotes slow combustion by creating a long flame (and also suppressing the generation of nitrogen oxides). This allows the duct burner to achieve stable combustion.

[0047] [2] In some embodiments, in the configuration described in [1] above, the main hole is configured with a jetting angle (θ1) of 20 degrees or more and less than 40 degrees relative to the central axis of the nozzle, the sub-hole is configured with a jetting angle (θ2) of 40 degrees or more and less than 50 degrees relative to the central axis of the nozzle, and the angle (θ3) of the flame stabilizing surface relative to the central axis of the nozzle is 40 degrees or more and 50 degrees or less.

[0048] According to the configuration described in [2] above, by setting the jet angle of the main hole (the angle of elevation relative to the central axis of the nozzle) to less than 40 degrees, slow combustion due to a long flame can be promoted. On the other hand, if the jet angle of the main hole is less than 20 degrees, the flame becomes excessively long, which may affect the heat absorption characteristics of the waste heat boiler that supplies the exhaust gas heated by the duct burner. Furthermore, by setting the jet angle of the sub-hole to 40 degrees or more, the nozzle can have a high flame-stabilizing effect. Therefore, by setting the jet angle of the main hole to between 20 degrees and 40 degrees and between 40 degrees and 50 degrees, stable combustion in the duct burner can be achieved.

[0049] [3] In some embodiments, in the configuration described in [1] or [2] above, the plate-like member has at least one through hole (18) formed therein, extending from the flame-holding surface to the surface (16) opposite the flame-holding surface.

[0050] According to the configuration described in [3] above, it is possible to adjust the amount of exhaust gas supplied to the vicinity of the nozzle where the gas fuel is ejected.

[0051] [4] In some embodiments, in the configuration described in [3] above, a plurality of the through holes are formed in the plate-like member, and when the ratio of the area of ​​the plurality of through holes to the area of ​​the flame stabilizing surface is defined as the aperture ratio, the aperture ratio is 20% or more and 50% or less.

[0052] If the aperture ratio is less than 20%, the amount of exhaust gas passing through the through holes will be small, and the amount of exhaust gas required to cool the flame stabilizer will be insufficient, which may cause the flame stabilizer to become red-hot. If the aperture ratio exceeds 50%, the flame stabilization effect may be reduced depending on the type of gas fuel. According to the configuration described in [4] above, the aperture ratio is 20% or more and 50% or less, so the generation of nitrogen oxides can be suitably suppressed.

[0053] [5] In some embodiments, in the configuration described in any one of [1] to [4] above, the at least one main hole includes a plurality of the main holes arranged around the central axis of the nozzle, the at least one sub-hole includes a plurality of the sub-holes arranged around the central axis of the nozzle, and the nozzle includes an ignition nozzle (20) formed with a small diameter hole (21) that is smaller in diameter than the sub-holes and is configured to eject the gas fuel from the central axis side of the nozzle than the plurality of main holes and the plurality of sub-holes.

[0054] According to the configuration described in [5] above, the small diameter hole ejects the gas fuel closer to the central axis of the nozzle than the main holes and sub-holes, so the area in which the gas fuel ignites and burns when the duct burner is started is expanded, thereby improving the ignition performance of the duct burner.

[0055] [6] In some embodiments, the configuration described in [5] above further comprises an ignition device (30) provided in a duct (122) having an inner wall surface (124) that defines the exhaust gas flow path, the at least one nozzle includes a plurality of the nozzles, and the nozzle of the plurality of nozzles that is located closest to the ignition device is the ignition nozzle.

[0056] According to the configuration described in [6] above, the ignition performance of the duct burner can be improved without making all or most of the multiple nozzles ignition nozzles.

[0057] [7] In some embodiments, in the configuration described in any one of [1] to [6] above, the at least one nozzle includes a plurality of the nozzles arranged along a left-right direction (D1), and the pair of plate-shaped members are arranged along a top-bottom direction (D2).

[0058] According to the configuration described in [7] above, it is possible to provide a duct burner in which a plurality of nozzles are arranged in the left-right direction and a pair of plate-like members are arranged in the up-down direction.

[0059] [8] In some embodiments, in the configuration described in [7] above, the at least one main hole includes a plurality of the main holes, the at least one sub-hole includes a plurality of the sub-holes, and the plurality of main holes and the plurality of sub-holes are arranged alternately around the central axis of the nozzle.

[0060] According to the configuration described in [8] above, the gas fuel is ejected from the plurality of main holes evenly and uniformly with respect to the central axis of the nozzle, and from the plurality of sub-holes evenly and uniformly with respect to the central axis of the nozzle, so that slow combustion due to the long flame can be continued smoothly.

[0061] [9] In some embodiments, in the configuration described in [8] above, the plurality of nozzles include a left nozzle (40) and a right nozzle (42) adjacent to the left nozzle on the right, and when the duct burner is viewed from the downstream side of the exhaust gas flow path, the angular position (θ) of an imaginary line (L3) extending upward from the central axis of the nozzle is defined as 0 degrees, the angular position increases as the nozzle rotates clockwise around the central axis of the nozzle as the center of rotation, and the angular position when the imaginary line rotates once is defined as 360 degrees, each of the left nozzle and the right nozzle includes: an upper sub-hole (44) that is one of the plurality of sub-holes and whose angular position is equal to or greater than 0 degrees and equal to or less than 10 degrees, or equal to or greater than 350 degrees and equal to or less than 360 degrees; and a lower sub-hole (46) that is one of the plurality of sub-holes and whose angular position is equal to or greater than 170 degrees and equal to or less than 190 degrees.

[0062] The exhaust gas passes through through holes formed in each of a pair of plate-like members aligned in the vertical direction and is supplied to the vicinity of the location where the gas fuel is ejected from the nozzle. That is, the exhaust gas is supplied from above or below the nozzle. According to the configuration described in [9] above, since the left nozzle and the right nozzle each include an upper sub-hole and a lower sub-hole, the gas fuel ejected from the upper sub-hole and the lower sub-hole can be quickly mixed with the exhaust gas.

[0063]

[10] In some embodiments, in the configuration described in [9] above, the left nozzle includes a right sub-hole that is one of the plurality of sub-holes and has an angular position that is equal to or greater than 80 degrees and equal to or less than 100 degrees, and the right nozzle includes a left sub-hole that is one of the plurality of sub-holes and has an angular position that is equal to or greater than 260 degrees and equal to or less than 280 degrees.

[0064] According to the configuration described in

[10] above, the left nozzle can ignite the right nozzle, or the right nozzle can ignite the left nozzle.

[0065]

[11] In some embodiments, in the configuration described in [9] above, the nozzle further includes a second sub-hole configured to eject the gas fuel at an ejection angle of 50 degrees or more and 90 degrees or less with respect to a central axis of the nozzle, and the angular position of the second sub-hole is 80 degrees or more and 100 degrees or less, or 260 degrees or more and 280 degrees or less.

[0066] According to the configuration described in

[11] above, the second sub-hole has a larger ejection angle than the right sub-hole and the left sub-hole described in

[10] above, so that a nozzle having the second sub-hole can quickly ignite the nozzles adjacent to it.

[0067]

[12] In some embodiments, in the configuration according to any one of [1] to

[11] above, the gas fuel is hydrogen gas or a hydrocarbon gas.

[0068] According to the configuration described in

[12] above, a duct burner that uses hydrogen gas or a hydrocarbon-based gas can be stably burned.

[0069]

[13] A gas turbine system according to the present disclosure includes: a gas turbine that uses hydrogen gas as fuel; and the duct burner according to any one of [1] to

[12] above.

[0070] According to the configuration described in

[13] above, it is possible to provide a gas turbine system equipped with a duct burner that performs stable combustion.

[0071] DESCRIPTION OF SYMBOLS 1 Duct burner 2 Fuel supply pipe 4 Nozzle 6 Flame holder 8A Upper plate-shaped member 8B Lower plate-shaped member 10 Main hole 12 Sub-hole 14 Flame holding surface 18 Through-hole 20 Ignition nozzle 21 Small diameter hole 30 Ignition device 40 Left nozzle 42 Right nozzle 44 Upper sub-hole 46 Lower sub-hole 48 Right sub-hole 50 Left sub-hole 54 Second sub-hole 100 Gas turbine system 110 Gas turbine 112 Compressor 113 Rotating shaft 114 Combustor 116 Turbine 120 Exhaust gas flow path 122 Duct 124 Inner wall surface of duct 130 Waste heat recovery boiler 140 Generator A1 Air A2 Compressed air A3 Fuel A4 Combustion gas D1 Left-right direction D2 Up-down direction F Gas fuel G Exhaust gas L1 First straight line L2 Second straight line L3 Virtual line O Central axis of nozzle

Claims

1. A duct burner arranged in an exhaust gas flow path through which exhaust gas discharged from a gas turbine flows, comprising: at least one nozzle for spraying gas fuel into the exhaust gas flow path; and a flame stabilizer including a pair of plate-shaped members located on opposite sides of the nozzle and moving away from the central axis of the nozzle toward the downstream side of the exhaust gas flow path, wherein the nozzle includes at least one sub-hole configured to spray the gas fuel along a flame-stabilizing surface of the plate-shaped member on the downstream side of the exhaust gas flow path, and at least one main hole having a larger diameter than the sub-hole and configured to spray the gas fuel at a tilt toward the central axis of the nozzle relative to the sub-hole.

2. A duct burner as described in claim 1, wherein the main hole is configured with a jet angle of 20 degrees or more and less than 40 degrees relative to the central axis of the nozzle, the sub-hole is configured with a jet angle of 40 degrees or more and less than 50 degrees relative to the central axis of the nozzle, and the angle of the flame-holding surface relative to the central axis of the nozzle is 40 degrees or more and 50 degrees or less.

3. A duct burner as claimed in claim 1 or 2, wherein said plate-like member is formed with at least one through hole extending from said flame-holding surface to a surface opposite said flame-holding surface.

4. A duct burner as described in claim 3, wherein a plurality of said through holes are formed in said plate-like member, and the ratio of the area of ​​said plurality of through holes to the area of ​​said flame-holding surface is defined as an aperture ratio, said aperture ratio being 20% ​​or more and 50% or less.

5. A duct burner as described in claim 1 or 2, wherein the at least one main hole includes a plurality of the main holes arranged around a central axis of the nozzle, the at least one sub-hole includes a plurality of the sub-holes arranged around the central axis of the nozzle, and the nozzle includes an ignition nozzle in which a small diameter hole is formed, the small diameter hole being smaller in diameter than the sub-holes and configured to eject the gas fuel from the central axis side of the nozzle relative to the plurality of main holes and the plurality of sub-holes.

6. The duct burner according to claim 5, further comprising an ignition device provided in a duct having an inner wall surface that defines the exhaust gas flow path, wherein the at least one nozzle includes a plurality of the nozzles, and the nozzle among the plurality of nozzles that is disposed closest to the ignition device is the ignition nozzle.

7. A duct burner as claimed in claim 1 or 2, wherein said at least one nozzle includes a plurality of said nozzles arranged along the left-right direction, and said pair of plate-like members are arranged along the up-down direction.

8. The duct burner according to claim 7, wherein the at least one main hole includes a plurality of the main holes, the at least one sub-hole includes a plurality of the sub-holes, and each of the plurality of the main holes and the plurality of the sub-holes is arranged alternately around a central axis of the nozzle.

9. A duct burner as described in claim 8, wherein the multiple nozzles include a left nozzle and a right nozzle adjacent to the right of the left nozzle, and when the duct burner is viewed from the downstream side of the exhaust gas flow path, the angular position of an imaginary line extending upward from the central axis of the nozzle is defined as 0 degree, the angular position increases as the nozzle rotates clockwise around the central axis of the nozzle as the center of rotation, and the angular position of the imaginary line once rotates is defined as 360 degrees, wherein each of the left nozzle and the right nozzle includes: an upper sub-hole which is one of the multiple sub-holes and whose angular position is equal to or greater than 0 degrees and equal to or less than 10 degrees, or equal to or greater than 350 degrees and equal to or less than 360 degrees, and a lower sub-hole which is one of the multiple sub-holes and whose angular position is equal to or greater than 170 degrees and equal to or less than 190 degrees.

10. A duct burner as described in claim 9, wherein the left nozzle includes a right sub-hole that is one of the plurality of sub-holes and has an angular position that is equal to or greater than 80 degrees and equal to or less than 100 degrees, and the right nozzle includes a left sub-hole that is one of the plurality of sub-holes and has an angular position that is equal to or greater than 260 degrees and equal to or less than 280 degrees.

11. A duct burner as described in claim 9, wherein the nozzle further comprises a second sub-hole configured to eject the gas fuel at an ejection angle of 50 degrees or more and 90 degrees or less relative to a central axis of the nozzle, and the angular position of the second sub-hole is 80 degrees or more and 100 degrees or less, or 260 degrees or more and 280 degrees or less.

12. The duct burner according to claim 1 or 2, wherein the gas fuel is hydrogen gas or a hydrocarbon gas.

13. A gas turbine system comprising: a gas turbine that uses hydrogen gas as fuel; and the duct burner according to claim 1 or 2.

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