Duct burner, gas turbine system, and combustion method for duct burner

Abstract

The duct burner according to the present invention is disposed in an exhaust gas flow path through which exhaust gas discharged from a gas turbine flows and is configured so that exhaust gas having a temperature of

Description

[Technical Field]

[0001] This invention relates to a channel burner, a gas turbine system equipped with the channel burner, and a combustion method using the channel burner. This application claims priority based on Japanese Patent Application No. 2023-137784 filed with the Japanese Patent Office on August 28, 2023, the contents of which are incorporated herein by reference. [Previous Technology]

[0002] For example, as disclosed in Non-Patent Document 1, in a gas turbine cogeneration system comprising a gas turbine and a waste heat recovery boiler, a channel burner is installed upstream of the waste heat recovery boiler to increase the heat recovery capacity. The channel burner injects fuel into the exhaust gas discharged from the gas turbine, utilizing the oxygen contained in the exhaust gas for combustion heating. [Prior Art Documents] [Non-Patent Documents]

[0003] [Non-Patent Document 1] IHI Technical Report Vol.49 No.2 (2009-6) P103-P107 [Summary of the Invention]

[0004] [Problem to be solved by the invention] It is preferable to have as little nitrogen oxides (NOx) as possible in exhaust gas. However, Non-Patent Document 1 does not disclose or imply a technique for reducing the amount of NOx in exhaust gas by means of a channel burner.

[0005] This invention was made in view of the above-mentioned problems, and provides a channel burner that can reduce the amount of nitrogen oxides contained in exhaust gas, and a combustion method for the channel burner. [Technical Means for Solving the Problem]

[0006] In order to achieve the above objective, the channel burner of the present invention is disposed in an exhaust flow path through which exhaust gas discharged from a gas turbine flows, wherein the exhaust gas flows into the channel burner at a temperature of 500 degrees or less and an oxygen concentration of 14% or less, and includes a nozzle that sprays hydrogen-containing gaseous fuel into the exhaust flow path.

[0007] To achieve the above objective, the combustion method of the channel burner of the present invention includes the following steps: injecting gaseous fuel into exhaust gas discharged from a gas turbine at a temperature of 500 degrees Celsius or less and an oxygen concentration of 14% or less to form a flame. [Effects of the Invention]

[0008] According to the channel burner and the combustion method of the channel burner of the present invention, the amount of nitrogen oxides contained in the exhaust gas can be reduced.

Implementation Method

[0010] Hereinafter, an embodiment of the channel burner and a combustion method of the channel burner according to the present invention will be described with reference to the drawings. This embodiment is an example of the present invention and does not limit the disclosure; any modifications can be made within the scope of the technical concept of the present invention.

[0011] <Gas Turbine> Figure 1 is a schematic diagram showing the structure of a gas turbine system 100 with a channel burner 1 in several embodiments. As shown in Figure 1, the gas turbine system 100 includes: a gas turbine 110, an exhaust flow path 120 through which exhaust gas G discharged from the gas turbine 110 flows, a heat recovery boiler 130 disposed in the exhaust flow path 120, and a channel burner 1 in several embodiments.

[0012] The gas turbine 110 includes: a compressor 112, a combustor 114, and a turbine 116. The compressor 112 compresses externally supplied air A1 to produce compressed air A2. The combustor 114 injects fuel A3 into the compressed air A2 produced by the compressor 112 to burn it, thereby producing combustion gas A4. Fuel A3 is not particularly limited, but is hydrogen in this embodiment. In several embodiments, fuel A3 may be, for example, a hydrocarbon gas such as LPG or LNG.

[0013] The turbine 116 is driven to rotate by the passage of combustion gas A4 generated by the burner 114, converting the thermal energy of the combustion gas A4 into rotational energy. The turbine 116 is connected to the compressor 112 via a rotating shaft 113, transmitting the rotational energy to the compressor 112. The compressor 112 is driven using 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 rotating shaft 113. The generator 140 uses the rotational energy of the turbine 116 to generate electricity.

[0014] The exhaust flow path 120 is defined by the inner wall surface 124 of the cylindrical channel 122 (see Figure 2). The exhaust heat recovery boiler 130 uses the thermal energy of the exhaust gas G to heat the supply water to generate steam. The supply target of the exhaust gas G 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 the absorbent.

[0015] The channel burner 1 is located upstream of the exhaust flow path 120, further upstream than the exhaust heat recovery boiler 130. The channel burner 1 is configured to allow exhaust gas G with a temperature of 500 degrees Celsius or less and an oxygen concentration of 14% or less to flow in. In several embodiments, the channel burner 1 also includes an adjustment device (heat transfer tube 10, spray device 12, and exhaust circulation line 14 described later) for adjusting the temperature or oxygen concentration of the exhaust gas G. In several embodiments, the channel burner 1 is configured to allow exhaust gas G with a temperature of 500 degrees Celsius or less and an oxygen concentration of 10% or less to flow in. Furthermore, in several embodiments, the gas turbine system 100 includes an exhaust adjustment device that adjusts the temperature of the exhaust gas G to 500 degrees Celsius or less and the oxygen concentration to 14% or less. In this case, the channel burner 1 may not need to include an adjustment device. That is, as long as the channel burner 1 is located in the exhaust flow path 120, exhaust gas G with a temperature of 500 degrees Celsius or less and an oxygen concentration of 14% or less will flow in.

[0016] Hereinafter, the exhaust gas G flowing upstream of the exhaust flow path 120 beyond the nozzle 2 will be referred to as inlet-side exhaust gas G1 (G), the exhaust gas G flowing downstream of the exhaust flow path 120 beyond the nozzle 2 and upstream of the exhaust flow path 120 beyond the heat recovery boiler 130 will be referred to as outlet-side exhaust gas G2 (G), and the exhaust gas G flowing downstream of the exhaust flow path 120 beyond the heat recovery boiler 130 will be referred to as heat recovery exhaust gas G3 (G). In one embodiment, inlet-side exhaust gas G1 is exhaust gas G flowing at or upstream of the inlet of the channel burner 1. The inlet of the channel burner 1, for example, is located in the direction in which the exhaust flow path 120 extends, at a position overlapping with the fuel supply pipe 4 described later. The upstream side of the inlet of the channel burner 1 is located between the fuel supply pipe 4 and the adjustment device in the exhaust flow path 120.

[0017] <First Embodiment> (Structure) The structure of the channel burner 1 according to the first embodiment will be described. Figure 2 is a schematic diagram showing the structure of the channel burner 1 according to the first embodiment. As shown in Figure 2, the channel burner 1 includes a nozzle 2, which sprays gaseous fuel F containing hydrogen into the exhaust flow path 120. In the first embodiment, the channel burner 1 further includes a fuel supply pipe 4 and a flame retainer 6. The fuel supply pipe 4 has a cylindrical shape and gaseous fuel F flows through it. The fuel supply pipe 4 extends in the exhaust flow path 120 and is connected to one or more nozzles 2. The flame retainer 6 has a pair of plate-shaped members 8 separated from the central axis O of the nozzle 2. The pair of plate-shaped members 8 are arranged side by side along the vertical direction D1. Each of the pair of plate-shaped members 8 has a through hole 9.

[0018] In this invention, "hydrogen-containing gaseous fuel F" refers to a fuel containing hydrogen and other fuels (mixed combustion) or fuel containing only hydrogen (exclusive combustion). Furthermore, fuels containing hydrogen and other fuels can be further categorized into fuels primarily composed of hydrogen (hydrogen volume percentage of 50% or more) or fuels primarily composed of other fuels (hydrogen volume percentage of less than 50%). "Hydrogen-containing gaseous fuel F" encompasses all of these cases.

[0019] As shown in FIG. 2, in the first embodiment, the channel burner 1 further includes a heat transfer tube 10 located upstream of the exhaust flow path 120, above the nozzle 2. This heat transfer tube 10 has a cylindrical shape, and a refrigerant C, at a lower temperature than the inlet-side exhaust gas G1, flows inside it. The refrigerant C is not particularly limited, but it can be, for example, water supplied to the heat recovery boiler 130. In the first embodiment, the refrigerant C flows from top to bottom, but the present invention is not limited to this configuration. The refrigerant C can also flow from bottom to top or from left to right.

[0020] As shown in FIG. 2, in a first embodiment, the channel burner 1 further includes a spray device 12 located upstream of the exhaust flow path 120, above the nozzle 2. This spray device 12 sprays water W onto the inlet-side exhaust gas G1. In the first embodiment, the spray device 12 is located upstream of the exhaust flow path 120, above the heat transfer tube 10, but the invention is not limited to this embodiment. The spray device 12 may also be located downstream of the exhaust flow path 120, above the heat transfer tube 10. In the first embodiment, the spray device 12 is located at the upper part of the channel 122 and sprays water W downwards, but the invention is not limited to this embodiment. The spray device 12 may also spray water W upwards, to the left, or to the right. In several embodiments, the spray device 12 sprays steam instead of water W.

[0021] In the first embodiment, the flow direction of the refrigerant C flowing through the heat transfer tube 10 and the spray direction of the water W sprayed from the spray device 12 are both from top to bottom, but the present invention is not limited to this embodiment. The flow direction of the refrigerant C and the spray direction of the water W may also be opposite to each other.

[0022] As shown in FIG. 2, in the first embodiment, the channel burner 1 further includes an exhaust recirculation line 14, which guides a portion of the exhaust gas G3 after heat recovery (hereinafter referred to as recirculated exhaust gas G3a(G)) from a portion 121 downstream of the exhaust flow path 120 above the heat recovery boiler 130 to a portion 123 upstream of the exhaust flow path 120 above the nozzle 2. The inlet 15 and outlet 17 of the exhaust recirculation line 14 are respectively formed on the inner wall surface 124 of the channel 122. A blower is provided in the exhaust recirculation line 14 to blow the recirculated exhaust gas G3a to the upstream side of the exhaust flow path 120 above the nozzle 2. The position of the outlet 17 of the exhaust recirculation line 14 is not particularly limited, and is determined, for example, based on the flow rate of the exhaust gas G1 at the inlet side or the volume of the exhaust flow path 120 from the outlet 17 of the exhaust recirculation line 14 to the channel burner 1.

[0023] As shown in FIG. 2, in the first embodiment, the channel burner 1 further includes a contact pipe 18, which is configured to pass through the flame X formed by the combustion of the gaseous fuel F. The contact pipe 18 extends along the vertical direction D1 and passes through the area where the flame X is formed. This area will vary due to the ejection pressure of the gaseous fuel F, etc., but can be predicted in advance.

[0024] (Function and Effect) The function and effect of the channel burner 1 in the first embodiment will be explained. Figure 3 is a graph showing the relationship between inlet temperature and NOx reduction rate. The horizontal axis represents inlet temperature, and the vertical axis represents NOx reduction rate. Inlet temperature is the temperature of the exhaust gas G1 flowing into the inlet side of the channel burner 1. NOx reduction rate is the value obtained by dividing the difference between the amount of NOx contained in the exhaust gas G1 flowing into the inlet side of the channel burner 1 and the amount of NOx contained in the exhaust gas G2 flowing out of the channel burner 1 by the amount of NOx contained in the exhaust gas G1 flowing into the inlet side of the channel burner 1. When the NOx reduction rate is greater than 0%, it means that the amount of NOx contained in the exhaust gas G1 is decreasing.

[0025] In Figure 3, the oxygen concentration is approximately 5.5% at P1, approximately 8% at P2, and approximately 12.5% ​​at P3. According to the inventors' understanding, as shown in Figure 3, if a hydrogen-containing gaseous fuel F is injected into exhaust gas G at a temperature below 500 degrees Celsius and an oxygen concentration below 14% for combustion heating, the amount of NOx contained in the inlet-side exhaust gas G1 will decrease. According to the first embodiment, the channel burner 1 allows the inlet-side exhaust gas G1 at a temperature below 500 degrees Celsius and an oxygen concentration below 14% to flow in. Therefore, a channel burner 1 can be provided that can reduce the amount of NOx contained in the inlet-side exhaust gas G1.

[0026] However, as shown in Figure 3, the NOx reduction rate tends to be higher on the side with lower oxygen concentration. By configuring the exhaust flow path 120 such that the oxygen concentration of the inlet-side exhaust gas G1 is less than 10%, a channel burner 1 can be provided, which can further reduce the amount of NOx contained in the inlet-side exhaust gas G1.

[0027] According to the first embodiment, the channel burner 1 includes a heat transfer tube 10 and a spray device 12 located upstream of the exhaust flow path 120, above the nozzle 2. Therefore, the inlet-side exhaust gas G1 is cooled by heat exchange with the refrigerant C flowing within the heat transfer tube 10. Similarly, the inlet-side exhaust gas G1 is cooled by water W sprayed from the spray device 12. Therefore, by adjusting the temperature of the inlet-side exhaust gas G1 flowing into the channel burner 1, it can be reduced to below 500 degrees Celsius.

[0028] According to the first embodiment, the channel burner 1 includes an exhaust gas recirculation line 14. Therefore, the recirculated exhaust gas G3a returns to the upstream side of the exhaust flow path 120, which is further upstream than the nozzle 2. The channel burner 1 consumes the oxygen contained in the inlet-side exhaust gas G1 to heat the inlet-side exhaust gas G1, so the amount of oxygen contained in the exhaust gas G3 after heat recovery is relatively small. Therefore, by returning the recirculated exhaust gas G3a obtained from the exhaust gas G3 after heat recovery to the upstream side of the exhaust flow path 120, which is further upstream than the nozzle 2, the oxygen concentration of the inlet-side exhaust gas G1 flowing into the channel burner 1 can be adjusted and reduced to below 14%.

[0029] According to the first embodiment, the channel burner 1 includes a contact tube 18. Therefore, by bringing the flame X into contact with the contact tube 18, the flame temperature is reduced, thereby suppressing the generation of NOx caused by combustion heating of the channel burner 1.

[0030] In the first embodiment, the outlet 17 of the exhaust recirculation line 14 is formed on the inner wall surface 124 of the channel 122, but the outlet 17 of the exhaust recirculation line 14 may also be located inside the exhaust flow path 120. Figure 4 is a diagram that schematically shows the structure of a modified example of the exhaust recirculation line 14.

[0031] As illustrated in Figure 4, the exhaust recirculation line 14 includes an exhaust pipe 20 located within the exhaust flow path 120. An outlet 17 is formed in the exhaust pipe 20, located inside the inner wall surface 124 of the passage 122 in the radial direction D2. The exhaust pipe 20 extends from the inner wall surface 124 of the passage 122 toward the inner side of the passage 122 in the radial direction D2 (the center of the exhaust flow path 120). In the radial direction D2 of the passage 122, the outlet 17 of the exhaust recirculation line 14 overlaps with the channel burner 1.

[0032] According to the configuration illustrated in Figure 4, the exhaust recirculation line 14 includes an exhaust pipe 20, thereby allowing the outlet 17 of the exhaust recirculation line 14 to be positioned at any location within the exhaust flow path 120. In the radial direction of the passage 122, a portion of the exhaust gas G1 flowing through the exhaust flow path 120 that overlaps with the passage burner 1, and a portion of G1a flowing near the passage burner 1, will be burned and heated by the passage burner 1. The remaining portion of G1b will not be burned and heated by the passage burner 1. Therefore, by positioning the outlet 17 of the exhaust recirculation line 14 and the passage burner 1 in the radial direction D2 of the passage 122, the reduction in oxygen concentration of the remaining portion of the inlet-side exhaust gas G1 G1 can be suppressed, thereby efficiently reducing the oxygen concentration of a portion of the inlet-side exhaust gas G1 G1 G1a to below 14%.

[0033] Figure 5 is a schematic diagram showing one example of the structure of the exhaust pipe 20, viewed from the downstream side of the exhaust flow path 120. Figure 6 is a schematic cross-sectional view in the direction of the arrow along line AA in Figure 5. As illustrated in Figures 5 and 6, the exhaust pipe 20 includes a horizontal pipe portion 22 and a protrusion 24.

[0034] The horizontal tube portion 22 extends in the left-right direction D3. A protrusion 24 protrudes from the horizontal tube portion 22 toward the downstream side of the exhaust flow path 120. The protrusion 24 surrounds the outer peripheral side of the nozzle 2. An opening 26 is formed in the protrusion 24, opening toward the downstream side of the exhaust flow path 120, serving as the outlet 17 of the exhaust circulation line 14. The front end 28 of the protrusion 24 (one end downstream of the exhaust flow path 120) is located upstream of the exhaust flow path 120, beyond the nozzle 2's outlet orifice.

[0035] According to the example configuration shown in Figure 5, the outlet 17 of the exhaust recirculation pipeline 14 is located near the nozzle 2's outlet hole, so that the recirculated exhaust gas G3a can be quickly mixed with the gaseous fuel F.

[0036] <Second Embodiment> The channel burner 1 of the second embodiment will be described. The channel burner 1 of the second embodiment differs from the first embodiment in that the gaseous fuel F contains hydrocarbon gas, and the nozzle 2 further includes a main orifice 40 and a secondary orifice 42. In the second embodiment, the same reference numerals are used for components identical to those in the first embodiment, and detailed descriptions are omitted.

[0037] (Structure) Figure 7 is a schematic diagram showing the structure of the channel burner 1 in the second embodiment. The channel burner 1 is equipped with a nozzle 2, which sprays a gaseous fuel Fc containing hydrocarbon gases into the exhaust flow path 120. The gaseous fuel Fc is, for example, LPG or LNG.

[0038] Figure 8 is a schematic diagram showing the structure of the nozzle 2 in the second embodiment. As shown in Figure 8, in the second embodiment, the nozzle 2 includes: a main orifice 40 configured to eject gaseous fuel Fc, and a secondary orifice 42 with a diameter smaller than that of the main orifice 40. The secondary orifice 42 is configured to eject the gaseous fuel Fc at an angle to the side opposite to the central axis O of the nozzle 2, which is closer to the main orifice 40. The secondary orifice 42 is configured to eject along the heat-resistant surface 8a downstream of the exhaust flow path 120 of the plate-shaped member 8.

[0039] A specific structural example of the main hole 40 and the secondary hole 42 will be described. The main hole 40 and the secondary hole 42 each extend in a straight line. The angle formed by the virtual first straight line L1 extending in the ejection direction of the main hole 40 and the central axis O of the nozzle 2 is the main hole ejection angle θ1. The angle formed by the virtual second straight line L2 extending in the ejection direction of the secondary hole 42 and the central axis O of the nozzle 2 is the secondary hole ejection angle θ2. The main hole ejection angle θ1 is 20 degrees or more and less than 40 degrees. The secondary hole ejection angle θ2 is 40 degrees or more and less than 50 degrees.

[0040] (Function, Effect) The function and effect of the channel burner 1 in the second embodiment will be explained. Figure 9 is a graph showing the relationship between inlet temperature and NOx reduction rate, with the horizontal axis representing inlet temperature and the vertical axis representing NOx reduction rate. In Figure 9, the oxygen concentration at P4 is approximately 12%.

[0041] According to the inventors' understanding, as shown in FIG9, if a gaseous fuel Fc containing hydrocarbon gases is injected into the exhaust gas G at a temperature of 500 degrees or below and an oxygen concentration of 14% or below for combustion heating, the amount of NOx contained in the inlet-side exhaust gas G1 will decrease. However, hydrocarbon gases have a lower combustion rate and poorer ignition or combustibility compared to hydrogen. Therefore, under the above-described conditions, the inlet-side exhaust gas G1 may have unstable combustion in the channel burner 1.

[0042] According to the second embodiment, the main orifice 40 is inclined further toward the central axis O of the nozzle 2 than the secondary orifice 42 to spray gaseous fuel Fc, thus promoting slow combustion caused by elongated flame, thereby stabilizing combustion in the channel burner 1. Therefore, even when using gaseous fuel Fc containing hydrocarbon gases, the channel burner 1 can reduce the amount of NOx contained in the inlet-side exhaust gas G1.

[0043] In the second embodiment, the fuel A3 of the gas turbine 110 is hydrogen, but it can also be a hydrocarbon gas such as LPG. Figure 10 is a graph showing the relationship between inlet temperature and NOx reduction rate, with the horizontal axis representing inlet temperature and the vertical axis representing NOx reduction rate. In Figure 10, the oxygen concentration is approximately 8.5% at P5 and approximately 13% at P6. According to the inventors' understanding, as shown in Figure 10, even if the fuel A3 is a hydrocarbon gas, if a gaseous fuel Fc containing hydrocarbon gas is injected into the exhaust gas G at a temperature of 500 degrees or below and an oxygen concentration of 14% or below for combustion heating, the amount of NOx contained in the inlet-side exhaust gas G1 will be reduced. Therefore, even if the fuel A3 of the gas turbine 110 is a hydrocarbon gas and a gaseous fuel Fc containing hydrocarbon gas is used, a channel burner 1 can be provided, which can reduce the amount of NOx contained in the inlet-side exhaust gas G1.

[0044] <Combustion Method of Channel Burner> A combustion method for channel burner 1 using the channel burner 1 of the first embodiment will be described. Figure 11 is a flowchart of the combustion method of channel burner 1. As shown in Figure 11, the combustion method of channel burner 1 includes a combustion heating step S1, in which gaseous fuel F is injected into exhaust gas G discharged from gas turbine 110 at a temperature of 500 degrees Celsius or less and an oxygen concentration of 14% or less to form a flame X. According to this method, the amount of NOx contained in exhaust gas G can be reduced. Furthermore, the above-described combustion method of channel burner 1 can also be performed using channel burner 1 of the second embodiment.

[0045] The contents recorded in the above-mentioned embodiments can be understood as follows, for example.

[0046] [1] The channel burner (1) of the present invention is disposed in an exhaust flow path (120) through which exhaust gas (G) discharged from a gas turbine (110) flows. The exhaust gas flows into the channel burner at a temperature of 500 degrees or less and an oxygen concentration of 14% or less. It includes a nozzle (2) that sprays hydrogen-containing gaseous fuel (F) into the exhaust flow path.

[0047] According to the inventors' understanding, it is known that if a hydrogen-containing gaseous fuel is injected into the exhaust gas at a temperature of 500 degrees or less and an oxygen concentration of 14% or less for combustion heating, the amount of nitrogen oxides contained in the exhaust gas will be reduced. Therefore, according to the structure described above [1], a channel burner can be provided that can reduce the amount of nitrogen oxides contained in the exhaust gas.

[0048] [2] In several embodiments, the structure described above[1] is further provided with a heat transfer tube (10), which is located upstream of the aforementioned exhaust flow path, and a refrigerant (C) with a lower temperature than the aforementioned exhaust flows through it.

[0049] According to the structure described above[2], the temperature of the exhaust can be reduced to below 500 degrees before the exhaust is heated by combustion of gaseous fuel.

[0050] [3] In several embodiments, the structure described in [1] or [2] above is further provided with a spraying device (12), which is located upstream of the aforementioned exhaust flow path, above the aforementioned nozzle, to spray water (W) or steam onto the aforementioned exhaust.

[0051] According to the structure described above[3], the temperature of the exhaust can be reduced to below 500 degrees before the exhaust is heated by combustion of gaseous fuel.

[0052] [4] In several embodiments, in any of the above-described [1] to [3], a heat recovery boiler (130) that uses the aforementioned exhaust to generate steam is provided on the downstream side of the aforementioned exhaust flow path, which is further provided with an exhaust circulation line (14) that guides a portion (G3a) of the aforementioned exhaust from the downstream side of the aforementioned exhaust flow path, which is further downstream of the aforementioned heat recovery boiler, to the upstream side of the aforementioned exhaust flow path, which is further upstream of the aforementioned nozzle.

[0053] According to the structure described above[4], before the exhaust gas is heated by combustion of gaseous fuel, the oxygen concentration contained in the exhaust gas can be reduced to below 14%.

[0054] [5] In several embodiments, in the structure described above[4], the aforementioned exhaust circulation pipeline includes an exhaust pipe (20) located in an exhaust flow path through which the aforementioned exhaust flows, and forms an outlet (17) of the aforementioned exhaust circulation pipeline.

[0055] A channel burner heats a portion of the exhaust gas flowing through the exhaust flow path. According to the structure described above [5], the outlet of the exhaust circulation line is positioned at any location within the exhaust flow path, thereby efficiently reducing the oxygen concentration of the portion of the exhaust gas that is heated by the channel burner to below 14%.

[0056] [6] In several embodiments, in the structure described above[5], the aforementioned exhaust pipe includes: a horizontal pipe portion (22), a protrusion (24) that protrudes from the aforementioned horizontal pipe portion and surrounds the outer periphery of the aforementioned nozzle, and an opening (26) is formed in the aforementioned protrusion that opens toward the downstream side of the aforementioned exhaust flow path as the aforementioned outlet of the aforementioned exhaust circulation pipeline.

[0057] According to the structure described above [6], the exhaust gas from the heat recovery boiler can be rapidly mixed with the gaseous fuel.

[0058] [7] In several embodiments, in any of the above-described [1] to [6], a contact tube (18) is further provided, which is configured to pass through the flame (X) formed by the combustion of the aforementioned gaseous fuel.

[0059] According to the structure described above[7], the flame is brought into contact with the contact tube to reduce the flame temperature, thereby suppressing the generation of NOx caused by combustion heating of the channel burner.

[0060] [8] In several embodiments, in any of the above-described [1] to [7] structures, the oxygen concentration of the aforementioned exhaust gas is 10% or less.

[0061] According to the construction described above[8], a channel burner can be provided, which can further reduce the amount of nitrogen oxides contained in the exhaust.

[0062] [9] The channel burner (1) of the present invention is disposed in an exhaust flow path (120) through which exhaust gas (G) discharged from a gas turbine (110) with a temperature of 500 degrees or less and an oxygen concentration of 14% or less flows. It includes a nozzle (2) that sprays gaseous fuel (Fc) containing hydrocarbon gas into the exhaust flow path. The nozzle includes: a main hole (40) configured to spray the gaseous fuel; and a secondary hole (42) with a diameter smaller than the main hole and configured to spray the gaseous fuel at an angle to the side opposite to the central axis (O) of the nozzle than the main hole.

[0063] According to the inventors' understanding, if a gaseous fuel containing hydrocarbon gases is injected into the exhaust gas at a temperature below 500 degrees Celsius and an oxygen concentration below 14% for combustion heating, the amount of nitrogen oxides contained in the exhaust gas will decrease. However, hydrocarbon gases have a lower combustion rate and poorer ignition or combustibility compared to hydrogen. Therefore, under the above-mentioned exhaust gas conditions, there is a risk of unstable combustion in the channel burner.

[0064] According to the structure described above [9], the main orifice is inclined towards the central axis of the nozzle to spray gaseous fuel, which can promote slow combustion caused by elongated flame, thus making the combustion of the channel burner more stable. Therefore, even when gaseous fuel containing hydrocarbon gases is used, a channel burner can be provided, which can reduce the amount of nitrogen oxides contained in the exhaust gas.

[0065]

[10] The gas turbine system (100) of the present invention comprises: a gas turbine (110) for use with hydrogen as fuel, and a channel burner (1) as described in any of [1] to [9] above.

[0066] According to the construction described above

[10] , a gas turbine system with a channel burner can be provided, which can reduce the amount of nitrogen oxides contained in the exhaust gas.

[0067]

[11] The combustion method of the channel burner of the present invention includes step (S1), which sprays gaseous fuel (F) to form flame (X) from exhaust gas (G) discharged from gas turbine (110) at a temperature of 500 degrees or less and an oxygen concentration of 14% or less.

[0068] The amount of nitrogen oxides contained in exhaust gas can be reduced by the method described above

[11] . [Simplified Explanation of the Diagram]

[0009] [Figure 1] A diagram schematically showing the structure of a gas turbine system with a channel burner in several embodiments. [Figure 2] A diagram schematically showing the structure of the channel burner in the first embodiment. [Figure 3] A graph showing the relationship between inlet temperature and NOx reduction rate. [Figure 4] A diagram schematically showing the structure of a modified exhaust recirculation pipeline. [Figure 5] A diagram schematically showing an example of the structure of an exhaust pipe. [Figure 6] A schematic cross-sectional view in the direction of the arrow AA in Figure 5. [Figure 7] A diagram schematically showing the structure of the channel burner in the second embodiment. [Figure 8] A diagram schematically showing the structure of the nozzle in the second embodiment. [Figure 9] A graph showing the relationship between inlet temperature and NOx reduction rate. [Figure 10] A graph showing the relationship between inlet temperature and NOx reduction rate. [Figure 11] A flowchart of the combustion method of the channel burner.

Claims

1. A channel burner configured to be disposed in an exhaust flow path through which exhaust gas discharged from a gas turbine flows, the exhaust gas flowing into the channel burner at a temperature of 500 degrees or less and an oxygen concentration of 14% or less, comprising: a nozzle that sprays hydrogen-containing gaseous fuel into the exhaust flow path.

2. The channel burner as described in claim 1, wherein, It further includes a heat transfer tube, which is located upstream of the aforementioned exhaust flow path, even further than the aforementioned nozzle, and through which flows a refrigerant at a lower temperature than the aforementioned exhaust.

3. The channel burner as described in claim 1 or 2, wherein, It further includes a spraying device, which is located upstream of the aforementioned exhaust flow path, above the aforementioned nozzle, to spray water or steam onto the aforementioned exhaust.

4. The channel burner as described in claim 1 or 2, wherein, Downstream of the aforementioned exhaust flow path, further from the aforementioned nozzle, there is a heat recovery boiler that uses the aforementioned exhaust to generate steam, and further includes an exhaust circulation line that guides a portion of the aforementioned exhaust from the downstream side of the aforementioned exhaust flow path to the upstream side of the aforementioned exhaust flow path, further from the aforementioned nozzle.

5. The channel burner as described in claim 4, wherein, The aforementioned exhaust circulation pipeline includes an exhaust pipe located within the aforementioned exhaust flow path, forming an outlet for the aforementioned exhaust circulation pipeline.

6. The channel burner as described in claim 5, wherein, The aforementioned exhaust pipe includes: a horizontal pipe portion, a protrusion that protrudes from the aforementioned horizontal pipe portion and surrounds the outer periphery of the aforementioned nozzle, and an opening that opens toward the downstream side of the aforementioned exhaust flow path is formed in the aforementioned protrusion to serve as the aforementioned outlet of the aforementioned exhaust circulation pipeline.

7. The channel burner as described in claim 1 or 2, wherein, It further includes a contact tube, which is configured to pass through the flames generated by the combustion of the aforementioned gaseous fuel.

8. The channel burner as described in claim 1 or 2, wherein, The oxygen concentration in the aforementioned exhaust gas is below 10%.

9. A channel burner disposed in an exhaust flow path through which exhaust gas from a gas turbine flows, having a temperature of 500 degrees Celsius or less and an oxygen concentration of 14% or less, comprising a nozzle that sprays gaseous fuel containing hydrocarbon gases into the exhaust flow path, the nozzle comprising: a main orifice configured to spray the gaseous fuel; and a secondary orifice having a diameter smaller than the main orifice and configured to spray the gaseous fuel at an angle to a side opposite to the central axis of the nozzle than the main orifice.

10. A gas turbine system comprising: a gas turbine for use with hydrogen as fuel, and a channel burner as described in claim 1 or 2.

11. A combustion method for a channel burner, comprising the following steps: injecting gaseous fuel into exhaust gas from a gas turbine at a temperature of 500 degrees or less and an oxygen concentration of 14% or less to form a flame.

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