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

Abstract

To reduce an amount of nitrogen oxide contained in exhaust gas.SOLUTION: A duct burner is arranged in an exhaust gas flow path through which exhaust gas discharged from a gas turbine circulates, and is configured to allow exhaust gas having a temperature of 500 degrees or less and an oxygen concentration of 14% or less to flow therein. The duct burner comprises a nozzle that ejects gas fuel containing hydrogen into the exhaust gas flow path.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a duct burner, a gas turbine system including the duct burner, and a combustion method for the duct burner. [Background technology]

[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 may be provided upstream of the heat recovery boiler in order 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 by utilizing the oxygen contained in the exhaust gas. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] IHI Technical Report VOL.49 No.2(2009-6) P103-P107 Summary of the Invention [Problem to be solved by the invention]

[0004] It is desirable for the amount of nitrogen oxides (NOx) contained in exhaust gas to be as small as possible. However, Non-Patent Document 1 does not disclose or suggest a technology for reducing the amount of NOx contained in exhaust gas by using a duct burner.

[0005] The present disclosure has been made in consideration of the above-mentioned problems, and has an object to provide a duct burner and a combustion method for the duct burner that are capable of reducing the amount of nitrogen oxides contained in exhaust gas. [Means for solving the problem]

[0006] In order to achieve the above-mentioned objective, 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 is configured so that the exhaust gas having a temperature of 500 degrees or less and an oxygen concentration of 14% or less flows in, and is equipped with a nozzle that sprays gas fuel containing hydrogen into the exhaust gas flow path.

[0007] In order to achieve the above-mentioned objective, the duct burner combustion method of the present disclosure includes a step of injecting gas fuel into exhaust gas discharged from a gas turbine, having a temperature of 500 degrees or less and an oxygen concentration of 14% or less, to form a flame. Effect of the Invention

[0008] According to the duct burner and the combustion method using the duct burner of the present disclosure, the amount of nitrogen oxides contained in exhaust gas can be reduced. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram illustrating a configuration of a gas turbine system including a duct burner according to some embodiments. [Diagram 2] FIG. 1 is a diagram illustrating a schematic configuration of a duct burner according to a first embodiment. [Diagram 3] 4 is a graph showing the relationship between the inlet temperature and the NOx reduction rate. [Figure 4] FIG. 13 is a diagram illustrating a schematic configuration of a modified example of an exhaust gas circulation line. [Diagram 5] FIG. 2 is a diagram illustrating an example of the configuration of an exhaust gas pipe. [Figure 6] 6 is a schematic cross-sectional view taken along the line AA in FIG. 5. [Figure 7] FIG. 6 is a diagram illustrating a schematic configuration of a duct burner according to a second embodiment. [Figure 8] FIG. 11 is a diagram illustrating a schematic configuration of a nozzle according to a second embodiment. [Figure 9] 4 is a graph showing the relationship between the inlet temperature and the NOx reduction rate. [Figure 10]4 is a graph showing the relationship between the inlet temperature and the NOx reduction rate. [Figure 11] 4 is a flowchart of a combustion method of the duct burner. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, a duct burner and a combustion method of the 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, and does not limit the present disclosure. The embodiment can be arbitrarily modified within the scope of the technical idea of ​​the present disclosure.

[0011] <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 heat recovery steam generator 130 that is disposed in the exhaust gas flow path 120, and a duct burner 1 according to some embodiments.

[0012] The gas turbine 110 includes a compressor 112, a combustor 114, and a turbine 116. The compressor 112 compresses air A1 supplied from the outside to generate compressed air A2. The combustor 114 generates combustion gas A4 by injecting fuel A3 into the compressed air A2 generated by the compressor 112 and combusting the fuel A3. 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.

[0013] 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 rotating shaft 113, and transmits the rotational energy to the compressor 112. The compressor 112 is driven by 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 generates electric power by using the rotational energy of the turbine 116.

[0014] 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 feed water using thermal energy contained in the exhaust gas G. The exhaust gas G that has passed through the exhaust heat recovery boiler 130 is supplied to, but is not limited to, a CO2 absorption tower that absorbs CO2 from the exhaust gas G into an absorbing liquid, for example.

[0015] The duct burner 1 is disposed upstream of the heat recovery boiler 130 in the exhaust gas flow passage 120. The duct burner 1 is configured to receive exhaust gas G having a temperature of 500° C. or less and an oxygen concentration of 14% or less. In some embodiments, the duct burner 1 further includes an adjustment device (a heat transfer tube 10, a spray device 12, and an exhaust gas circulation line 14, which will be described later) for adjusting the temperature of the exhaust gas G and the oxygen concentration of the exhaust gas G. In some embodiments, the duct burner 1 is configured to receive exhaust gas G having a temperature of 500° C. or less and an oxygen concentration of 10% or less. In some embodiments, the gas turbine system 100 includes an exhaust gas adjustment device that adjusts the temperature of the exhaust gas G to 500° C. or less and the oxygen concentration to 14% or less. In this case, the duct burner 1 does not need to include an adjustment device. In other words, the duct burner 1 is configured to receive exhaust gas G having a temperature of 500° C. or less and an oxygen concentration of 14% or less by simply being disposed in the exhaust gas flow passage 120.

[0016] Hereinafter, the exhaust gas G flowing upstream of the exhaust gas passage 120 from the nozzle 2 is described as inlet-side exhaust gas G1 (G), the exhaust gas G flowing downstream of the exhaust gas passage 120 from the nozzle 2 and upstream of the exhaust heat recovery boiler 130 is described as outlet-side exhaust gas G2 (G), and the exhaust gas G flowing downstream of the exhaust gas passage 120 from the exhaust heat recovery boiler 130 is described as exhaust gas G3 (G) after exhaust heat recovery. In one embodiment, the inlet-side exhaust gas G1 is exhaust gas G flowing at the inlet of the duct burner 1 or immediately upstream of the inlet of the duct burner 1. The inlet of the duct burner 1 is positioned so as to overlap with the fuel supply pipe 4 described later in the direction in which the exhaust gas passage 120 extends, for example. The immediately upstream side of the inlet of the duct burner 1 is located between the fuel supply pipe 4 and the adjustment device in the exhaust gas passage 120.

[0017] First Embodiment (composition) The configuration of the duct burner 1 according to the first embodiment will be described. FIG. 2 is a diagram showing a schematic configuration of the duct burner 1 according to the first embodiment. As shown in FIG. 2, the duct burner 1 includes a nozzle 2 that ejects a gas fuel F containing hydrogen into an exhaust gas passage 120. In the first embodiment, the duct burner 1 further includes a fuel supply pipe 4 and a flame stabilizer 6. The fuel supply pipe 4 has a cylindrical shape, and the gas fuel F flows inside. The fuel supply pipe 4 extends through the exhaust gas passage 120, and one or more nozzles 2 are connected to the fuel supply pipe 4. The flame stabilizer 6 has a pair of plate-shaped members 8 spaced apart from the central axis O of the nozzle 2. The pair of plate-shaped members 8 are arranged along the up-down direction D1. Each of the pair of plate-shaped members 8 has a through hole 9 formed therein.

[0018] In this disclosure, "hydrogen-containing gas fuel F" includes fuels that contain hydrogen and fuels other than hydrogen (mixed combustion), and fuels that only contain hydrogen (monocarbon combustion). Furthermore, fuels that contain hydrogen and fuels other than hydrogen can be classified as fuels in which hydrogen is the main component (volume ratio of hydrogen is 50% or more) and fuels in which a fuel other than hydrogen is the main component (volume ratio of hydrogen is less than 50%). "Hydrogen-containing gas fuel F" includes all of these cases.

[0019] As shown in FIG. 2, in the first embodiment, the duct burner 1 further includes a heat transfer tube 10 provided upstream of the nozzle 2 in the exhaust gas passage 120. The heat transfer tube 10 has a cylindrical shape, and a refrigerant C having a lower temperature than the inlet side exhaust gas G1 flows inside. The refrigerant C is not particularly limited, and may be taken from the feed water supplied to the heat recovery boiler 130, for example. In the first embodiment, the refrigerant C flows from top to bottom, but the present disclosure is not limited to this form. The refrigerant C may flow from bottom to top, or from left to right.

[0020] As shown in FIG. 2, in the first embodiment, the duct burner 1 further includes a spray device 12 provided upstream of the nozzle 2 in the exhaust gas passage 120. The spray device 12 sprays water W into the inlet-side exhaust gas G1. In the first embodiment, the spray device 12 is located upstream of the heat transfer tube 10 in the exhaust gas passage 120, but the present disclosure is not limited to this form. The spray device 12 may be located downstream of the heat transfer tube 10 in the exhaust gas passage 120. In the first embodiment, the spray device 12 is provided at the upper part of the duct 122 and sprays the water W downward, but the present disclosure is not limited to this form. The spray device 12 may spray the water W upward, left, or right. In some embodiments, the spray device 12 sprays steam instead of the 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 disclosure is not limited to this embodiment. The flow direction of the refrigerant C and the spray direction of the water W may be opposite to each other.

[0022] As shown in FIG. 2, in the first embodiment, the duct burner 1 further includes an exhaust gas circulation line 14 that guides a part of the exhaust gas G3 after exhaust heat recovery (hereinafter, referred to as circulating exhaust gas G3a(G)) from a downstream portion 121 of the exhaust gas passage 120 from the exhaust heat recovery boiler 130 to an upstream portion 123 of the exhaust gas passage 120 from the nozzle 2. The inlet 15 and the outlet 17 of the exhaust gas circulation line 14 are formed on the inner wall surface 124 of the duct 122. The exhaust gas circulation line 14 is provided with a blower for blowing the circulating exhaust gas G3a to the upstream side of the exhaust gas passage 120 from the nozzle 2. The position of the outlet 17 of the exhaust gas circulation line 14 is not particularly limited, and is determined based on, for example, the flow rate of the inlet-side exhaust gas G1 and the volume of the exhaust gas passage 120 from the outlet 17 of the exhaust gas circulation line 14 to the duct burner 1.

[0023] 2, in the first embodiment, the duct burner 1 further includes a contact tube 18 provided so as to cross the flame X formed by the combustion of the gas fuel F. The contact tube 18 extends along the vertical direction D1 and crosses the region where the flame X is formed. This region changes depending on the ejection pressure of the gas fuel F, etc., but can be estimated in advance.

[0024] (Action and effect) The action and effect of the duct burner 1 according to the first embodiment will be described. FIG. 3 is a graph showing the relationship between the inlet temperature and the NOx reduction rate, with the horizontal axis representing the inlet temperature and the vertical axis representing the NOx reduction rate. The inlet temperature is the temperature of the inlet side exhaust gas G1 flowing into the duct burner 1. The NOx reduction rate is a value obtained by dividing the difference between the amount of NOx contained in the inlet side exhaust gas G1 flowing into the duct burner 1 and the amount of NOx contained in the outlet side exhaust gas G2 flowing out from the duct burner 1 by the amount of NOx contained in the inlet side exhaust gas G1 flowing into the duct burner 1. If the NOx reduction rate is greater than 0%, it means that the amount of NOx contained in the inlet side exhaust gas G1 is reduced.

[0025] In FIG. 3, P1 has an oxygen concentration of about 5.5%, P2 has an oxygen concentration of about 8%, and P3 has an oxygen concentration of about 12.5%. According to the findings of the present inventors, as shown in FIG. 3, when a gas fuel F containing hydrogen is injected into an exhaust gas G having a temperature of 500° C. or less and an oxygen concentration of 14% or less to perform combustion heating, the amount of NOx contained in the inlet-side exhaust gas G1 is reduced. According to the first embodiment, the duct burner 1 is configured to receive the inlet-side exhaust gas G1 having a temperature of 500° C. or less and an oxygen concentration of 14% or less. Therefore, it is possible to provide a duct burner 1 capable of reducing the amount of NOx contained in the inlet-side exhaust gas G1.

[0026] Incidentally, as shown in Fig. 3, the NOx reduction rate tends to be higher as the oxygen concentration is lower. By arranging the exhaust gas flow passage 120 so that the oxygen concentration of the inlet side exhaust gas G1 is 10% or less, it is possible to provide a duct burner 1 that can further reduce the amount of NOx contained in the inlet side exhaust gas G1.

[0027] According to the first embodiment, the duct burner 1 includes a heat transfer tube 10 and a spray device 12 located upstream of the nozzle 2 in the exhaust gas flow path 120. Therefore, the inlet side exhaust gas G1 exchanges heat with the refrigerant C flowing inside the heat transfer tube 10 and is cooled. Similarly, the inlet side exhaust gas G1 is cooled by the water W sprayed from the spray device 12. Therefore, the temperature of the inlet side exhaust gas G1 flowing into the duct burner 1 can be adjusted and lowered to 500 degrees or less.

[0028] According to the first embodiment, the duct burner 1 includes an exhaust gas circulation line 14. Therefore, the circulating exhaust gas G3a is returned upstream of the nozzle 2 in the exhaust gas passage 120. The duct burner 1 consumes oxygen contained in the inlet side exhaust gas G1 to burn and heat the inlet side exhaust gas G1, so the amount of oxygen contained in the exhaust gas G3 after exhaust heat recovery is small. Therefore, by returning the circulating exhaust gas G3a obtained from the exhaust gas G3 after exhaust heat recovery to the upstream side of the nozzle 2 in the exhaust gas passage 120, the oxygen concentration of the inlet side exhaust gas G1 flowing into the duct burner 1 can be adjusted and reduced to 14% or less.

[0029] According to the first embodiment, the duct burner 1 includes a contact tube 18. Therefore, by bringing the flame X into contact with the contact tube 18, the flame temperature can be reduced, and the generation of NOx due to the combustion heating of the duct burner 1 can be suppressed.

[0030] In the first embodiment, the outlet 17 of the exhaust gas circulation line 14 is formed on the inner wall surface 124 of the duct 122, but the outlet 17 of the exhaust gas circulation line 14 may be located inside the exhaust gas flow path 120. Fig. 4 is a diagram showing a schematic configuration of a modified example of the exhaust gas circulation line 14.

[0031] 4, the exhaust gas circulation line 14 includes an exhaust gas pipe 20 located in an exhaust gas flow path 120. An outlet 17 of the exhaust gas circulation line 14 is formed in the exhaust gas pipe 20 and located inside an inner wall surface 124 of the duct 122 in a radial direction D2 of the duct 122. The exhaust gas pipe 20 extends from the inner wall surface 124 of the duct 122 toward the inside of the radial direction D2 of the duct 122 (the center of the exhaust gas flow path 120). In the radial direction D2 of the duct 122, the outlet 17 of the exhaust gas circulation line 14 and the duct burner 1 are positioned so as to overlap each other.

[0032] 4, the exhaust gas circulation line 14 includes the exhaust gas pipe 20, so that the outlet 17 of the exhaust gas circulation line 14 can be disposed at any position in the exhaust gas flow path 120. In the radial direction of the duct 122, the inlet side exhaust gas G1 is combusted and heated by the duct burner 1 at a portion G1a of the exhaust gas flow path 120 that overlaps with the duct burner 1 and at a portion close to the duct burner 1, and the remaining portion G1b is not combusted and heated by the duct burner 1. Therefore, by positioning the outlet 17 of the exhaust gas circulation line 14 and the duct burner 1 so as to overlap each other in the radial direction D2 of the duct 122, a decrease in the oxygen concentration of the remaining portion G1b of the inlet side exhaust gas G1 is suppressed, and the oxygen concentration of the portion G1a of the inlet side exhaust gas G1 can be efficiently reduced to 14% or less.

[0033] Fig. 5 is a diagram illustrating an example of the configuration of the exhaust gas pipe 20, as viewed from the downstream side of the exhaust gas flow path 120. Fig. 6 is a schematic cross-sectional view taken along the line AA in Fig. 5. As illustrated in Figs. 5 and 6, the exhaust gas pipe 20 includes a header portion 22 and a protruding portion 24.

[0034] The header portion 22 extends along the left-right direction D3. The protruding portion 24 protrudes from the header portion 22 toward the downstream side of the exhaust gas flow path 120. The protruding portion 24 surrounds the outer periphery of the nozzle 2. The protruding portion 24 has an opening 26 that opens toward the downstream side of the exhaust gas flow path 120 as the outlet 17 of the exhaust gas circulation line 14. A tip 28 of the protruding portion 24 (one end on the downstream side of the exhaust gas flow path 120) is located upstream of the exhaust gas flow path 120 from the nozzle 2 outlet.

[0035] According to the embodiment illustrated in FIG. 5, the outlet 17 of the exhaust gas circulation line 14 is located near the ejection hole of the nozzle 2, so that the circulating exhaust gas G3a can be mixed with the gas fuel F quickly.

[0036] <Second embodiment> A duct burner 1 according to the second embodiment will be described. The duct burner 1 according to the second embodiment differs from the first embodiment in that the gas fuel F contains a hydrocarbon gas, and the nozzle 2 further includes a main hole 40 and a sub-hole 42. In the second embodiment, the same components as those in the first embodiment are given the same reference symbols, and detailed descriptions thereof will be omitted.

[0037] (composition) 7 is a diagram showing a schematic configuration of a duct burner 1 according to the second embodiment. The duct burner 1 includes a nozzle 2 that ejects a gas fuel Fc containing a hydrocarbon gas into an exhaust gas passage 120. The gas fuel Fc is, for example, LPG or LNG.

[0038] Fig. 8 is a diagram illustrating a schematic configuration of a nozzle 2 according to a second embodiment. As illustrated in Fig. 8, in the second embodiment, the nozzle 2 includes a main hole 40 configured to eject gas fuel Fc, and a sub-hole 42 having a smaller diameter than the main hole 40. The sub-hole 42 is configured to eject the gas fuel Fc at an inclination toward the opposite side to the central axis O of the nozzle 2 relative to the main hole 40. The sub-hole 42 is configured to eject the gas fuel Fc along a flame stabilizing surface 8a downstream of the exhaust gas passage 120 of the plate-shaped member 8.

[0039] An example of a specific configuration of the main hole 40 and the sub-hole 42 will be described. The main hole 40 and the sub-hole 42 each extend in a straight line. The angle formed by a 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 defined as the main hole ejection angle θ1. The angle formed by a virtual second straight line L2 extending in the ejection direction of the sub-hole 42 and the central axis O of the nozzle 2 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.

[0040] (Action and effect) The action and effect of the duct burner 1 according to the second embodiment will be described. Fig. 9 is a graph showing the relationship between the inlet temperature and the NOx reduction rate, where the horizontal axis represents the inlet temperature and the vertical axis represents the NOx reduction rate. In Fig. 9, P4 has an oxygen concentration of about 12%.

[0041] According to the findings of the present inventors, as shown in Fig. 9, when a gas fuel Fc containing a hydrocarbon gas is injected into an exhaust gas G having a temperature of 500°C or less and an oxygen concentration of 14% or less to perform combustion heating, the amount of NOx contained in the inlet side exhaust gas G1 is reduced. However, compared to hydrogen, the combustion speed of a hydrocarbon gas is slower and it is inferior in ignition and combustibility. Therefore, with the inlet side exhaust gas G1 under the above conditions, there is a risk that the combustion of the duct burner 1 will not be stable.

[0042] According to the second embodiment, the main hole 40 ejects the gas fuel Fc at a greater inclination toward the central axis O of the nozzle 2 than the sub-hole 42, which promotes slow combustion due to a longer flame, thereby stabilizing the combustion in the duct burner 1. Therefore, even when using a gas fuel Fc containing a hydrocarbon gas, it is possible to provide a duct burner 1 capable of reducing 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 gas, but may be a hydrocarbon gas such as LPG. FIG. 10 is a graph showing the relationship between the inlet temperature and the NOx reduction rate, where the horizontal axis represents the inlet temperature and the vertical axis represents the NOx reduction rate. In FIG. 10, P5 has an oxygen concentration of about 8.5%, and P6 has an oxygen concentration of about 13%. According to the findings of the present inventors, as shown in FIG. 10, even if the fuel A3 is a hydrocarbon gas, the amount of NOx contained in the inlet-side exhaust gas G1 is reduced when a gas fuel Fc containing a hydrocarbon gas is injected into an exhaust gas G having a temperature of 500 degrees or less and an oxygen concentration of 14% or less to perform combustion heating. Therefore, even if the fuel A3 of the gas turbine 110 is a hydrocarbon gas and a gas fuel Fc containing a hydrocarbon gas is applied, a duct burner 1 capable of reducing the amount of NOx contained in the inlet-side exhaust gas G1 can be provided.

[0044] <Duct burner combustion method> A combustion method of the duct burner 1 using the duct burner 1 according to the first embodiment will be described. FIG. 11 is a flowchart of the combustion method of the duct burner 1. As shown in FIG. 11, the combustion method of the duct burner 1 includes a combustion heating step S1 in which a gas fuel F is ejected into exhaust gas G discharged from a gas turbine 110 and having a temperature of 500 degrees 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 the exhaust gas G can be reduced. The above-mentioned combustion method of the duct burner 1 may be performed using the duct burner 1 according to the second embodiment.

[0045] The contents described in each of the above embodiments can be understood, for example, as follows.

[0046] [1] The duct burner (1) according to the present disclosure is A duct burner that is disposed in an exhaust gas flow path (120) through which exhaust gas (G) discharged from a gas turbine (110) flows, and is configured so that the exhaust gas having a temperature of 500° C. or less and an oxygen concentration of 14% or less flows into the duct burner, A nozzle (2) is provided for spraying gas fuel (F) containing hydrogen into the exhaust gas passage.

[0047] According to the findings of the present inventors, when exhaust gas having a temperature of 500°C or less and an oxygen concentration of 14% or less is combusted and heated by injecting a gas fuel containing hydrogen, the amount of nitrogen oxides contained in the exhaust gas is reduced. Therefore, according to the configuration described in [1] above, it is possible to provide a duct burner capable of reducing the amount of nitrogen oxides contained in the exhaust gas.

[0048] [2] In some embodiments, in the configuration described in [1] above, The apparatus further includes a heat transfer tube (10) that is provided upstream of the nozzle in the exhaust gas passage and through which a refrigerant (C) having a lower temperature than the exhaust gas flows.

[0049] According to the configuration described in [2] above, the temperature of the exhaust gas can be reduced to 500 degrees or less before the exhaust gas is combusted and heated by the gas fuel.

[0050] [3] In some embodiments, in the configuration described in [1] or [2] above, The exhaust gas purification plant further includes a spray device (12) that is provided upstream of the nozzle in the exhaust gas passage and that sprays water (W) or steam into the exhaust gas.

[0051] According to the configuration described in [3] above, the temperature of the exhaust gas can be reduced to 500 degrees or less before the exhaust gas is combusted and heated by the gas fuel.

[0052] [4] In some embodiments, in the configuration according to any one of [1] to [3] above, a heat recovery boiler (130) that generates steam by using the exhaust gas is provided downstream of the nozzle in the exhaust gas passage; The exhaust gas circulation system further includes an exhaust gas circulation line (14) that guides a part (G3a) of the exhaust gas from a downstream side of the exhaust gas passage relative to the heat recovery boiler to an upstream side of the exhaust gas passage relative to the nozzle.

[0053] According to the configuration described in [4] above, the oxygen concentration in the exhaust gas can be reduced to 14% or less before the exhaust gas is combusted and heated by the gas fuel.

[0054] [5] In some embodiments, in the configuration described in [4] above, The exhaust gas circulation line is located in an exhaust gas flow path through which the exhaust gas flows, and includes an exhaust gas pipe (20) in which an outlet (17) of the exhaust gas circulation line is formed.

[0055] The duct burner combusts and heats a portion of the exhaust gas flowing through the exhaust gas passage. According to the configuration described in [5] above, by locating the outlet of the exhaust gas circulation line at any position within the exhaust gas passage, the oxygen concentration in the portion of the exhaust gas that is the target of combustion and heating by the duct burner can be efficiently reduced to 14% or less.

[0056] [6] In some embodiments, in the configuration described in [5] above, The exhaust gas pipe includes a header portion (22) and a protruding portion (24) protruding from the header portion and surrounding an outer circumferential side of the nozzle, The protruding portion has an opening (26) that opens toward the downstream side of the exhaust gas flow passage as the outlet of the exhaust gas circulation line.

[0057] According to the configuration described in [6] above, the exhaust gas that has passed through the heat recovery steam generator can be quickly mixed with the gas fuel.

[0058] [7] In some embodiments, in the configuration according to any one of [1] to [6] above, The combustion apparatus further includes a contact tube (18) arranged to cross a flame (X) formed by the combustion of the gas fuel.

[0059] According to the configuration described in [7] above, the flame temperature can be reduced by bringing the flame into contact with the contact tube, and the generation of NOx due to the combustion heating of the duct burner can be suppressed.

[0060] [8] In some embodiments, in the configuration according to any one of [1] to [7] above, The exhaust gas has an oxygen concentration of 10% or less.

[0061] According to the configuration described in [8] above, a duct burner can be provided that can further reduce the amount of nitrogen oxides contained in exhaust gas.

[0062] [9] The duct burner (1) according to the present disclosure is A duct burner is disposed in an exhaust gas passage (120) through which exhaust gas (G) having a temperature of 500° C. or less and an oxygen concentration of 14% or less discharged from a gas turbine (110) flows, a nozzle (2) for ejecting a gas fuel (Fc) containing a hydrocarbon gas into the exhaust gas passage, The nozzle is a main hole (40) configured to eject the gas fuel; and a sub-hole (42) having a smaller diameter than the main hole and configured to eject the gas fuel at an incline toward the opposite side from the central axis (O) of the nozzle relative to the main hole.

[0063] According to the findings of the present inventors, it has been found that when a gas fuel containing a hydrocarbon gas is injected into exhaust gas having a temperature of 500°C or less and an oxygen concentration of 14% or less to perform combustion heating, the amount of nitrogen oxides contained in the exhaust gas is reduced. However, compared to hydrogen, the combustion speed of a hydrocarbon gas is slower and it is inferior in ignition and combustibility. Therefore, with exhaust gas under the above conditions, there is a risk that the combustion in the duct burner will be unstable.

[0064] According to the configuration described in [9] above, the main hole is inclined more toward the central axis of the nozzle than the sub-hole to eject the gas fuel, which promotes slow combustion by making the flame longer, and therefore stabilizes the combustion of the duct burner. Therefore, even when gas fuel containing a hydrocarbon gas is used, it is possible to provide a duct burner that can reduce the amount of nitrogen oxides contained in the exhaust gas.

[0065]

[10] A gas turbine system (100) according to the present disclosure includes: A gas turbine (110) that uses hydrogen gas as fuel; and a duct burner (1) according to any one of the above [1] to [9].

[0066] According to the configuration described in

[10] above, a gas turbine system equipped with a duct burner capable of reducing the amount of nitrogen oxides contained in exhaust gas can be provided.

[0067]

[11] The combustion method of the duct burner according to the present disclosure comprises: The method includes a step (S1) of forming a flame (X) by injecting gas fuel (F) into exhaust gas (G) discharged from a gas turbine (110) and having a temperature of 500 degrees or less and an oxygen concentration of 14% or less.

[0068] According to the method described in

[11] above, the amount of nitrogen oxides contained in exhaust gas can be reduced. [Explanation of symbols]

[0069] 1 Duct burner 2 Nozzles 4 Fuel supply pipe 6 Flame holder 8 Plate-shaped members 8a Flame holding surface 9 Through holes 10 Heat transfer tube 12 Spraying device 14 Exhaust gas circulation line 15 Exhaust gas recirculation line inlet 17 Outlet of exhaust gas recirculation line 18 Contact tube 20 Exhaust gas pipe 22 Header section 24 Protrusion 26 Opening of protrusion 28 Tip of protrusion 40 Main hole 42 Secondary hole 100 Gas Turbine System 110 Gas Turbine 112 Compressor 113 Rotational Axis 114 Combustor 116 Turbine 120 Exhaust gas flow path 121 The downstream part of the exhaust gas flow path from the heat recovery boiler 122 Duct 123 The upstream part of the exhaust gas flow path from the nozzle 124 Inner wall surface of duct 130 Waste heat recovery boiler 140 Generator A1 Air A2 Compressed air A3 fuel A4 Combustion gas C Refrigerant D1 Vertical direction D2 radial direction D3 Left / Right F Gas fuel (hydrogen) Fc Gas fuel (hydrocarbon gas) G. Exhaust gas G1 Inlet exhaust gas G2 Outlet exhaust gas G3 Exhaust gas with waste heat recovery G3a Recirculating exhaust gas L1 1st straight line L2 2nd straight line O center axis S1 Combustion heating step W water X flame

Claims

1. A duct burner that is disposed in an exhaust gas flow path through which exhaust gas discharged from a gas turbine flows, and is configured so that the exhaust gas having a temperature of 500° C. or less and an oxygen concentration of 14% or less flows into the duct burner, A nozzle is provided for ejecting a gas fuel containing hydrogen into the exhaust gas passage. Duct burner.

2. a heat transfer tube provided upstream of the exhaust gas flow passage from the nozzle and through which a refrigerant having a lower temperature than the exhaust gas flows; 2. The duct burner according to claim 1.

3. The exhaust gas purification system further includes a spray device that is provided upstream of the exhaust gas flow path from the nozzle and that sprays water or steam into the exhaust gas.

3. A duct burner according to claim 1 or 2.

4. a heat recovery boiler that generates steam using the exhaust gas is provided downstream of the nozzle in the exhaust gas flow path, The exhaust gas circulation line further guides a part of the exhaust gas from a downstream side of the exhaust gas passage relative to the exhaust heat recovery boiler to an upstream side of the exhaust gas passage relative to the nozzle.

3. A duct burner according to claim 1 or 2.

5. The exhaust gas circulation line is located in the exhaust gas flow path and includes an exhaust gas pipe through which an outlet of the exhaust gas circulation line is formed.

5. A duct burner according to claim 4.

6. the exhaust gas pipe includes a header portion and a protruding portion protruding from the header portion and surrounding an outer circumferential side of the nozzle, The protruding portion has an opening that opens toward a downstream side of the exhaust gas flow passage as the outlet of the exhaust gas circulation line.

6. A duct burner according to claim 5.

7. The combustion gas further includes a contact tube disposed across a flame formed by the combustion of the gas fuel.

3. A duct burner according to claim 1 or 2.

8. The exhaust gas has an oxygen concentration of 10% or less.

3. A duct burner according to claim 1 or 2.

9. A duct burner that is disposed in an exhaust gas flow path through which exhaust gas having a temperature of 500° C. or less and an oxygen concentration of 14% or less discharged from a gas turbine flows, a nozzle for ejecting a gas fuel containing a hydrocarbon gas into the exhaust gas passage, The nozzle is a main hole configured to eject the gas fuel; a sub-hole having a smaller diameter than the main hole and configured to eject the gas fuel at an inclination toward an opposite side to a central axis side of the nozzle than the main hole, Duct burner.

10. A gas turbine that uses hydrogen gas as fuel; The duct burner according to claim 1 or 2, Gas turbine systems.

11. The method includes a step of forming a flame by injecting gas fuel into exhaust gas discharged from a gas turbine and having a temperature of 500° C. or less and an oxygen concentration of 14% or less. Duct burner combustion method.

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