Gas turbine with a system for reducing combustion dynamics

Abstract

Gas turbine (10) which features: several burners (14) arranged in an annular shape around an axial centerline of the gas turbine, the several burners (14) comprising a first burner (14) and a second burner (14); wherein the first burner (14) comprises several annular tube bundles (58, 62) of fuel nozzles (34) arranged in a circular pattern around a center line of the first burner (14), each tube bundle (58, 62) comprising a fuel collection chamber (90) and several tubes (36) extending through it, each tube (36) having a tube inlet (86) upstream of the fuel collection chamber (90), a tube outlet (88) downstream of the fuel collection chamber (90) and a fuel injection device (94) providing a fluid connection between the fuel collection chamber (90) and the tube (36), the fuel injection device (94) being arranged at a first axial distance (96) from the tube outlet (88), and each tube (36) having the same first axial distance (96); wherein the second burner (14) has several tube bundles (58, 62) of fuel nozzles (34) arranged annularly around a center line of the second burner (14), each tube bundle (58, 62) having a fuel collection chamber (90) and several tubes (36) extending through it, each tube (36) having a tube inlet (86) upstream of the fuel collection chamber (90), a tube outlet (88) downstream of the fuel collection chamber (90), and a fuel injection device (84) providing a fluid connection between the fuel collection chamber (90) and the tube (36), the fuel injection device (94) being arranged in a first axial section (96) of the tube outlet (88), each tube (36) having the same first axial distance (96); and wherein the first axial distance (96) of one of the several tube bundles (58, 62) of the first burner (14) differs from the first axial distance (96) of one of the several tube bundles (58, 62) of the second burner (14).

Description

[0001] The present invention generally relates to a gas turbine having a system for reducing combustion dynamics.

[0002] Combustors are commonly used in industrial and commercial operations to burn fuel to produce combustion gases at high temperatures and pressures. For example, gas turbines and other turbomachinery typically contain one or more combustors to generate power or thrust. A typical gas turbine used to generate electrical power contains an axial-flow compressor at the front, several combustors in the middle, and a turbine at the rear. Ambient air enters the compressor as a working fluid, and the compressor progressively imparts kinetic energy to the working fluid to create a compressed working fluid in a high-energy state.The compressed working fluid leaves the compressor and flows through one or more fuel nozzles and / or tubes into the combustor chambers, where the compressed working fluid mixes with fuel before being burned to produce combustion gases at high temperature and pressure. The combustion gases flow to the turbine, where they expand to generate work. For example, the expansion of the combustion gases in the turbine can rotate a shaft connected to a generator to generate electricity.

[0003] Various factors influence the design and operation of burners. For example, higher combustion gas temperatures generally improve the thermodynamic efficiency of the burners. However, higher combustion gas temperatures also promote flame-holding conditions, in which the combustion flame migrates toward the fuel supplied through the fuel nozzles and potentially causes accelerated wear on the fuel nozzles in a relatively short period of time. In addition, higher combustion gas temperatures generally increase the disassociation rate of diatomic nitrogen, which leads to the production of nitrogen oxides (NO x ). Conversely, a lower combustion gas temperature, combined with reduced fuel flow and / or part-load operation (shutdown), substantially reduces the chemical reaction rates of the combustion gases, increasing the production of carbon monoxide and unburned hydrocarbons.

[0004] Although effective for enabling higher operating temperatures while protecting against flame holding and controlling undesirable emissions, some burners can, under specific operating conditions, generate combustion instabilities resulting from an interaction or coupling of the combustion process or flame dynamics with one or more acoustic resonant frequencies of the burner. For example, one mechanism of combustion instabilities may occur when acoustic pressure pulsations induce a mass flow fluctuation at a fuel inlet, which then leads to a fluctuation in the fuel / air ratio in the flame zone. If the resulting fluctuation in the fuel / air ratio and the acoustic pressure pulsations have a certain phase behavior (e.g., are nearly in phase), a self-excited feedback loop results.This mechanism and the resulting magnitude of the combustion dynamics depend on the delay time between the fuel injection and the time it reaches the flame zone, known in the art as the convection time (τ). As the convection time increases, the frequency of combustion instabilities decreases, and as the convection time decreases, the frequency of combustion instabilities increases. The result is combustion dynamics that can reduce the useful life of one or more combustors and / or downstream components. For example, the combustion dynamics can generate pressure pulses within the fuel nozzles and / or combustors, which can adversely affect the high-cycle fatigue life of these components, the stability of the combustion flame, the design limits of flame retention, and / or undesirable emissions.Alternatively, or additionally, combustion dynamics at specific frequencies with sufficient amplitudes that are in phase and coherent can generate undesirable resonances in the turbine and / or other downstream components. By shifting the frequency of combustion instability in one or more combustors relative to others, the overall coherence of the combustion system is reduced and burner-to-burner coupling is diminished. This reduces the ability of burner tone to cause a vibrational response in downstream components and also promotes destructive burner-to-burner interference, reducing combustion dynamic amplitudes.

[0005] DE 198 09 364 A1 discloses systems for reducing combustion dynamics in a burner comprising at least a first and a second fuel nozzle, each having a central body and a premixing tube surrounding the central body, which define a premixing channel between them. In one embodiment, fuel injection orifices for injecting fuel are arranged in the premixing channel. To decouple the combustion dynamics, the fuel injection orifices in the first and second fuel nozzles are arranged at different axial positions and thus at different axial distances from the combustion chamber.

[0006] DE 10 2009 003 639 A1 discloses a burner with a plurality of fuel nozzles or premixing tubes having premixing devices with fuel injectors and swirler blades in their interior, wherein the fuel injectors and / or the swirler blades are arranged in different fuel nozzles or premixing tubes at axially offset positions relative to one another in order to reduce the combustion dynamics.

[0007] DE 10 2011 055 475 A1 discloses a burner with multiple fuel nozzles, including a central fuel nozzle and multiple outer fuel nozzles arranged in a circular ring around the central fuel nozzle. Each fuel nozzle comprises a tube bundle with multiple premixing tubes for premixing air and fuel. The fuel injectors of all premixing tubes of all fuel nozzles are arranged at the same distance from the outlets of the premixing tubes. To reduce combustion dynamics, at least two adjacent fuel nozzles of the burner are arranged in a stepped manner so that their end sections located at the rear in the flow direction are axially offset from one another.

[0008] There remains a need for an improved system that adjusts the phase and / or coherence of the combustion dynamics generated by each burner to improve the thermodynamic efficiency of the burners, protect against accelerated wear, promote flame stability, and / or reduce undesirable emissions over a wide range of operating levels.

[0009] To meet this need, the invention provides a gas turbine with a combustion dynamics reduction system having the features of independent claim 1. Particularly preferred embodiments of the invention are the subject of the dependent claims.

[0010] A complete and basic description of the present invention, including the best mode thereof for carrying out the invention to one skilled in the art, is set forth below in the remainder of the specification with reference to the accompanying drawings, in which: Fig. 1 is a simplified side cross-sectional view of an exemplary prior art gas turbine in which the present invention may be used; Fig. 2 is a simplified side cross-sectional view of an exemplary burner according to various embodiments of the present invention; Fig. 3 an upstream plan view of the Fig. 2 is a cap assembly according to an embodiment not belonging to the claimed invention; Fig. 4 an upstream plan view of the Fig. 2 is a cap assembly according to an embodiment of the present invention; Fig. 5 an upstream plan view of the Fig. 2 is a cap assembly according to an alternative embodiment of the present invention; Fig. 6 a side cross-sectional view of the head end of the Fig. 3 along the line AA according to an embodiment which as such does not belong to the claimed invention; Fig. 7 is a system for reducing combustion dynamics according to an embodiment not belonging to the claimed invention as such; Fig. 8 is a system for reducing combustion dynamics according to another embodiment not per se belonging to the claimed invention; Fig. 9 a side cross-sectional view of the head end of the Fig. 5 along the line BB according to an embodiment of the present invention; Fig. 10 is a system for reducing combustion dynamics according to a second embodiment of the present invention; Fig. 11 is a system for reducing combustion dynamics according to an embodiment not belonging to the claimed invention; and Fig. 12 is an exemplary graph of burner dynamics according to various embodiments of the present invention.

[0011] Reference will now be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. The detailed description uses numerical and letter designations to refer to features in the drawings. The same or similar designations in the drawings or in the description have been used to refer to the same or similar parts of the invention. As used herein, the terms "first," "second," and "third" may be used interchangeably to distinguish one component from another and are not intended to indicate the location or importance of the individual components. Additionally, the terms "upstream" and "downstream" refer to the relative location of components in a fluid flow path. For example, if a fluid flows from component A to component B, component A is upstream of component B.Conversely, component B is downstream of component A when component B receives a fluid flow from component A.

[0012] Each example is provided by way of illustration of the invention and not by way of limitation. Indeed, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For example, features shown or described as part of one embodiment may be used with another embodiment to provide yet another embodiment of the invention. Thus, the present invention is intended to include such modifications and variations as fall within the scope of the appended claims and their equivalents.

[0013] Various embodiments of the present invention include a system and method for reducing combustion dynamics to improve thermodynamic efficiency, promote flame stability, and / or reduce undesirable emissions over a wide range of operating conditions. The system and method generally include a plurality of burners, and each burner includes one or more fuel nozzles and / or tubes and a combustion chamber downstream of the fuel nozzle(s) and / or tubes. Each fuel nozzle includes one or more fuel inlets and / or radially extending vanes, and each tube includes one or more fuel injectors. The system and method include various means for generating a combustion instability frequency in the first burner that is different from the combustion instability frequency in the second burner.Accordingly, various embodiments of the present invention may result in extended operating conditions, extended service life and / or maintenance intervals, improved flame-holding design distances, and / or reduced undesirable emissions. Although exemplary embodiments of the present invention are described primarily in the context of combustion dynamics in a gas turbine for illustrative purposes, those skilled in the art will readily recognize that embodiments of the present invention may be applied to any combustion dynamics and are not limited to any gas turbine unless specifically stated in the claims.

[0014] Fig. 1 provides a simplified cross-sectional view of an exemplary gas turbine 10 that may incorporate various embodiments of the present invention. As shown, the gas turbine 10 may generally include a compressor section 12 in the front, a plurality of combustors 14 radially arranged in a combustion section around the center, and a turbine section 16 in the rear. The compressor section 12 and the turbine section 16 may share a common rotor 18 connected to a generator 20 for generating electricity. A working fluid 22, such as ambient air, may enter the compressor section 12 and pass through alternating stages of stationary vanes 24 and rotating blades 26.A compressor housing 28 contains the working fluid 22, while the stationary guide vanes 24 and rotating blades 26 accelerate and direct the working fluid 22 to create a continuous flow of compressed working fluid 22. The majority of the compressed working fluid 22 flows through a compressor outlet plenum 30 to the combustors 14. A combustor housing 32 may circumferentially surround some or all of the combustors 14 to receive the working fluid 22 flowing from the compressor section. Fuel may be mixed with the compressed working fluid 22 in one or more fuel nozzles 34 and / or tubes 36. Possible fuels include, for example, one or more of blast furnace gas, coke oven gas, natural gas, vaporized liquefied natural gas (LNG), hydrogen, and propane. The mixture of fuel and compressed working fluid 22 may then flow into a combustion chamber 38 where it burns to produce combustion gases at high temperature and pressure.A transition channel 40 circumferentially surrounds at least a portion of the combustion chamber 38, and the combustion gases flow through the transition channel 40 to the turbine section 16.

[0015] The turbine section 16 may include alternating stages of stationary nozzles 42 and rotating blades 44. The stationary nozzles 42 direct the combustion gases to the next stage of rotating blades 44, and the combustion gases expand as they pass through the rotating blades 44, causing the rotating blades 44 and rotor 18 to rotate. The combustion gases then flow to the next stage of stationary nozzles 42, which direct the combustion gases to the next stage of rotating blades 44, and this process repeats in subsequent stages.

[0016] The burners 14 may be any type of burner known in the art, and the present invention is not limited to any particular burner design unless specifically stated in the claims. Fig. Figure 2 provides a simplified side cross-sectional view of an exemplary combustor 14 according to various embodiments of the present invention. The combustor housing 32 circumferentially surrounds at least a portion of the combustor 14 to contain the compressed working fluid 22 flowing from the compressor 12. As shown in Fig. 2, the burner housing 32 may be connected to or include an end cover 46 that extends radially over at least a portion of each burner 14 to provide an interface for delivering fuel, diluent, and / or other additives to each burner 14. Additionally, the burner housing 32 and the end cover 46 may combine to at least partially define a head end 48 within each burner 14. The fuel nozzles 34 and / or tubes 36 may be radially disposed within a cap assembly 50 that extends radially over at least a portion of each burner 14 downstream of the head end 48. An insert 52 may be connected to the cap assembly 50 to at least partially define the combustion chamber 38 downstream of the cap assembly 50.In this manner, the working fluid 22 may flow, for example, through flow holes 54 in an impingement sleeve 56 and along the exterior of the transition channel 40 and the insert 52 to provide convection cooling for the transition piece 40 and the insert 52. When the working fluid 22 reaches the head end 48, the working fluid 22 reverses its direction, and the fuel nozzles 34 and / or tubes 36 provide fluid communication for the working fluid 22 to flow through the cap assembly 50 and into the combustion chamber 38.

[0017] Although illustrated as substantially cylindrical, the radial cross-section of the fuel nozzles 34 and / or tubes 36 may have any geometric shape, and the present invention is not limited to any particular radial cross-section unless specifically stated in the claims. Additionally, various embodiments of the combustor 14 may include different numbers and arrangements of fuel nozzles 34 and / or tubes 36 in the cap assembly 50, and the Fig. 4-5 illustrate upstream plan views of exemplary arrangements of the fuel nozzles 34 and / or tubes 36 in the cap assembly 50 within the scope of the present invention. As shown in Fig. 3, which shows an embodiment which as such does not belong to the claimed invention, for example, several fuel nozzles 34 can be arranged radially around only one fuel nozzle 34. Alternatively, as in Fig. 4, the tubes 36 may be arranged radially throughout the cap assembly 50, and the tubes 36 may be divided into various groups to allow for multiple fuel supply areas across the operating areas of the burner 14. For example, the tubes 36 may be grouped into a plurality of annular tube bundles 58 circumferentially surrounding a central tube bundle 60 as shown in Fig. 4. Alternatively, as described in Fig. 5, a plurality of pie-shaped tube bundles 62 circumferentially surround only one fuel nozzle 34. During base load operations, fuel can be supplied to any fuel nozzle 34 and any Fig. 3-5, wherein the fuel flow from the central fuel nozzle 34 or the central tube bundle 60 and / or one or more circumferentially arranged fuel nozzles 34 or annular or pie-shaped tube bundles 58, 62 can be reduced or completely eliminated during reduced or shutdown operations. Those skilled in the art will readily recognize various other shapes and arrangements for the fuel nozzles 34, tubes 36, and tube bundles 58, 60, 62 from the teachings herein, and the particular shape and arrangement of the fuel nozzles 34, tubes 36, and tube bundles 58, 60, 62 are not limitations of the present invention unless specifically recited in the claims.

[0018] Fig. Figure 6 is a side cross-sectional view of the head end 48 of the Fig. 3 along the line AA according to an embodiment which as such does not belong to the claimed invention. As shown in the Fig. 3 and Fig. 6, the combustor 14 may include a plurality of fuel nozzles 34 radially arranged around a central fuel nozzle 34 substantially aligned with an axial centerline 64 of the combustor 14. Each fuel nozzle 34 may include a centerbody 66 extending axially downstream from the end cover 46 and a cover 68 circumferentially surrounding at least a portion of the centerbody 66 to define an annular passage 70 between the centerbody 66 and the cover 68. One or more vanes 72 may extend radially between the centerbody 66 and the cover 68, and the vanes 72 may be angled or curved to impart swirl to the working fluid 22 flowing through the annular passage 70 between the centerbody 66 and the cover 68. The vanes 72 and / or the center body 66 may include one or more fuel inlets 74.In this manner, fuel may be supplied to the center body 66 and / or the vanes 72, and the fuel inlets 74 provide fluid communication for the fuel to flow into the annular passage 70 and mix it with the working fluid 22 before the mixture reaches the combustion chamber 38.

[0019] If the fuel nozzles 34 are installed in the burner 14, as in the case of Fig. 2, the resulting combustion process in the combustion chamber 38 can generate heat release fluctuations, which in turn can couple with one or more acoustic modes of the burner 14 to produce combustion instabilities. One specific mechanism that can generate combustion instabilities occurs when the acoustic pulsations excited by heat release fluctuations cause mass flow fluctuations through the fuel inlets 74. For example, the pressure pulses associated with the combustion flames can propagate upstream of the combustion chamber 38 into each annular passage 70.Once the pressure pulses reach the fuel inlets 74 and / or vanes 72, the pressure pulses may interfere with the fuel flow through the fuel inlets 74 and / or over the vanes 72, creating fluctuations in the fuel / air mixture concentration that flow downstream toward the combustion flame. These fluctuations in the fuel / air ratio then travel downstream to the flame region, where they cause a heat release fluctuation. Provided the heat release fluctuation is approximately in phase with the pressure fluctuations, it promotes even further heat release fluctuations, creating a continuous feedback loop. Conversely, if the resulting heat release fluctuation and the pressure fluctuations are out of phase, destructive interference reduces the magnitude of the combustion instability frequency associated with the particular fuel nozzle 34.The combustion instability frequencies associated with the fuel nozzles 34 may, in turn, superimpose one another constructively or destructively to increase or decrease the amplitude of the combustion dynamics associated with the particular burner 14.

[0020] The resulting combustion instability frequencies are a function of the time it takes for the acoustic pressure pulse to reach the fuel inlet and then the resulting fuel / air ratio perturbation to reach the flame zone. This time is known in the art as the convection time or τ. The combustion instability frequencies generated by the interaction of the fuel / air ratio fluctuations and the acoustic pressure fluctuation are therefore inversely proportional to the axial distance between the fuel inlets 74 and / or the vanes 72 and the combustion chamber 38 (i.e., the end of the fuel nozzles 34 or the end of the shrouds 68). In specific embodiments, these combustion instability frequencies can be adjusted and / or tuned in one or more fuel nozzles 34 to influence the combustion dynamics associated with the individual burner 14. In the Fig. 3 and Fig. For example, in the specific embodiment illustrated in Figure 6, the combustor 16 may include a plurality of fuel nozzles 34 with a different axial spacing 76 between the fuel inlets 74 and / or the vanes 72 and the combustion chamber 38 for each fuel nozzle 34. Accordingly, the combustion instability frequency generated for each fuel nozzle 34 will be slightly different, reducing or eliminating constructive interference between the fuel nozzles 34 that increases an amplitude of the combustion dynamics associated with the particular combustor 14. Those skilled in the art will readily appreciate from the teachings herein that several combinations of variations in the axial spacings 76 between the fuel inlets 74 and / or the vanes 72 and the combustion chamber 38 are possible to achieve a desired combustion instability frequency for each fuel nozzle 74 and / or desired combustion dynamics for the particular combustor.For example, in particular embodiments, the axial distances 76 between the fuel inlets 74 and / or the vanes 72 and the combustion chamber 38 may be the same or different for some or all of the fuel nozzles 34 in a particular combustor 34, and the present invention is not limited to any particular combination of axial distances 76 unless specifically recited in the claims.

[0021] The combustion dynamics associated with multiple burners installed in the gas turbine 10 may interfere with each other either constructively or destructively to increase or decrease the amplitude and / or coherence of the combustion dynamics associated with the gas turbine 10. In specific embodiments, the combustion instability frequencies and / or the combustion dynamics associated with one or more burners 14 may be adjusted and / or tuned to influence the interaction with the combustion dynamics of another burner 14 and thus the combustion dynamics associated with the gas turbine 10. For example, Fig. 7 provides a system for reducing combustion dynamics and / or coherence of combustion dynamics according to a first embodiment, which as such does not belong to the claimed invention. In the Fig. In the special embodiment shown in Figure 7, several burners 14 were used as shown in Fig. 3 and Fig. 6 is arranged around an axis 78. The axis 78 may, for example, coincide with the rotor 18 in the gas turbine 10 that connects the compressor section 12 to the turbine section 16, although the present invention is not limited to the specific orientation of the axis 78 or the specific arrangement of the combustors 14 about the axis 78.

[0022] According to the presentation in Fig. 7, each burner 14 includes a plurality of fuel nozzles 34 with the combustion chamber 38 downstream of the fuel nozzles 34 as described above with reference to the Fig. 2, Fig. 3 and Fig. 6. In addition, the system further includes means for generating a combustion instability frequency in one burner 14 that is different from the combustion instability frequency in the other burner 14. The function of generating a combustion instability frequency in one burner 14 that is different from the combustion instability frequency in the other burner 14 reduces or prevents coherent or constructive interference between the combustion instability frequencies that could increase the amplitude of the combustion dynamics or increase the coherence of the combustion dynamics of two or more burners 14. The structure for the means may include a difference in one or more of the axial distances 76 between the fuel inlets 74 and the combustion chamber 38 and / or the vanes 72 and the combustion chamber 38 between the two burners 14. In the Fig. For example, in the specific embodiment illustrated in Figure 7, each axial distance 76 between the fuel inlets 74 and the combustion chamber 38 and between the vanes 72 and the combustion chamber 38 is different between the two burners 14. Accordingly, the device produces different combustion instability frequencies in the two burners 14. Those skilled in the art will readily appreciate from the teachings herein that several combinations of variations in the axial distances 76 between the fuel inlets 74 and the combustion chamber 38 and / or the vanes 72 and the combustion chamber 38 are possible to produce a combustion instability frequency in one burner 14 that is different from the combustion instability frequency in the other burner 14.For example, in particular embodiments, one or more axial distances 76 between the fuel inlets 74 and the combustion chamber 38 and / or the vanes 72 and the combustion chamber 38 for one or more of the fuel nozzles 34 in a particular combustor 14 may be the same or different compared to the other combustor 14, as long as the axial distances 76 are not all the same between both combustors 14, and the present invention is not limited to any particular combination of axial distances 76 unless specifically recited in the claims.

[0023] Fig. Figure 8 illustrates a system for reducing combustion dynamics according to another embodiment, which as such is not part of the claimed invention. As shown in Fig. 8, each burner 14 in turn includes a plurality of fuel nozzles 34 with the combustion chamber 38 downstream of the fuel nozzles 34 as described above with reference to the Fig. 2, Fig. 3, Fig. 6 and Fig. 7. In addition, the axial positions of the fuel inlets 74 and / or the guide elements 72 may be the same or different in each burner 14. In the Fig. For example, in the specific embodiment shown in Figure 8, the axial positions of the fuel inlets 74 and the guide elements 72 are different in the same burner 14, but the axial positions of the fuel inlets 74 and the guide elements 72 are repeated in both burners 14.

[0024] The Fig. The embodiment illustrated in Figure 8 again includes means for creating a combustion instability frequency or resonant frequency in one burner 14 that is different from the combustion instability frequency or resonant frequency in the other burner 14. In this particular embodiment, the structure for the means may include a difference in an axial length 40 of the cap assembly 50 in one burner 14 compared to the axial length 80 of the cap assembly in the other burner 14. With the axial positions of the fuel inlets 74 and the vanes 72 repeated in both burners 14, the difference in the axial lengths 80 between the two burners 14 creates a corresponding difference in the axial distances 76 between the fuel inlets 74 and the combustion chamber 38 and the vanes 72 and the combustion chamber 38 between the two burners 14.The difference in the axial distances 76 between the two burners 14 creates a corresponding difference in the combustion instability or resonant frequencies between the two burners 14. One skilled in the art will readily appreciate from the teachings herein that several combinations of variations in the axial distances 76 between the fuel inlets 74 and the combustion chamber 38 and / or the vanes 72 and the combustion chamber 38 are possible to create a combustion instability or resonant frequency in one burner 14 that is different from the combustion instability or resonant frequency in the other burner 14.For example, in particular embodiments, one or more axial distances 76 between the fuel inlets 74 and the combustion chamber 38 and / or the vanes 72 and the combustion chamber 38 may be the same or different for one or more of the fuel nozzles 34 in a particular combustor 14 compared to the other combustor 14, and the present invention is not limited to any particular combination of axial distances 76 unless specifically recited in the claims.

[0025] Fig. Figure 9 is a side cross-sectional view of the head end 48 of the Fig. 5 along line BB according to an embodiment of the present invention. As shown, the cap assembly 50 extends radially across at least a portion of the burner 14 and includes an upstream surface 82 axially separated from a downstream surface 84. The upstream and downstream surfaces 82, 84 may be substantially flat or straight and oriented perpendicular to the general flow of the working fluid 22 through the cap assembly 50. In the Fig. 9, the fuel nozzle 34 is again substantially aligned with the axial centerline 84 of the cap assembly 50 and extends through the cap assembly 50 to provide fluid communication through the cap assembly 50 to the combustion chamber 38. The fuel nozzle 34 may include any suitable structure known to those skilled in the art for mixing fuel with the working fluid 22 prior to entering the combustion chamber 38, and the present invention is not limited to any particular structure or configuration unless specifically recited in the claims. For example, as shown in Fig. 9, the fuel nozzle 34 comprises a central body 66, a cover 68, an annular passage 70, guide elements 72 and fuel inlets 74, as described above with reference to the Fig. 6 illustrated embodiment.

[0026] According to the presentation in the Fig. 5 and Fig. 9, the tubes 36 may be arranged circumferentially around the fuel nozzle 34 in pie-shaped tube bundles 62 and may extend from the upstream surface 82 through the downstream surface 84 of the cap assembly 50. Each tube 36 generally includes an inlet 86 proximate the upstream surface 82 and an outlet 88 proximate the downstream surface 84 to provide fluid communication through the cap assembly 50 and into the combustion chamber 38 downstream of the tubes 36.

[0027] According to the presentation in Fig. 9, the upstream and downstream surfaces 82, 84 may at least partially define a fuel plenum 90 within the cap assembly 50. A fuel line 92 may extend from the housing 32 and / or the end cover 46 through the upstream surface 82 to provide fluid communication for the flow of fuel within the fuel plenum 90. One or more of the tubes 36 may include a fuel injector 94 extending through the tubes 36 to provide fluid communication from the fuel plenum 90 into the tubes 36. The fuel injectors 94 may be radially, axially, and / or azimuthally angled to protrude and / or impart swirl to the fuel flowing through the fuel injectors 94 and into the tubes 36.The working fluid 22 can thus flow into the tube inlets 86, and fuel from the fuel line 92 can flow around the tubes 36 into the fuel plenum 90 to provide convection cooling to the tubes 36 before flowing through the fuel injectors 94 and into the tubes 36 to mix with the working fluid 22. The fuel-working fluid mixture can then flow through the tubes 36 and into the combustion chamber 38.

[0028] As mentioned above with reference to the Fig. 6, when the tubes 36 are installed in the burner 14, such as the one shown in Fig. 2, the resulting combustion process in the combustion chamber can generate heat release fluctuations, which in turn can couple with one or more acoustic modes of the burner 14 to produce combustion instabilities. One specific mechanism by which combustion instabilities can be generated occurs when the acoustic pulsations driven by the heat release fluctuations travel upstream to the fuel injectors 94, where they can interfere with the fuel flow through the fuel injectors 94 and create fluctuations in the fuel / air mixture concentration flowing downstream to the combustion flame. This fluctuation in the fuel / air ratio then travels downstream to the flame region, where it can cause a heat release fluctuation.Provided the resulting heat release fluctuation is approximately in phase with pressure fluctuations, it will further promote heat release fluctuations, completing a continuous feedback loop. Conversely, if the resulting heat release fluctuation and the pressure fluctuation are out of phase, destructive interference will reduce the magnitude of the combustion instability frequency associated with tubes 36, tube bundles 62, and / or cap assembly 50. The combustion instability frequencies associated with tubes 36 and / or tube bundles 62 may, in turn, constructively or destructively interfere with each other to increase or decrease the amplitude of the combustion dynamics associated with the particular combustor 14.

[0029] The resulting combustion instability frequencies are a function of the time it takes for the acoustic pressure pulse to reach the fuel inlet and then the resulting fuel / air ratio perturbation to reach the flame zone. This time is known in the art as the convection time or τ. The combustion instability frequencies generated by the interaction of the fuel / air ratio fluctuations and the acoustic pressure fluctuation are therefore inversely proportional to the axial distance between the fuel injectors 94 and the combustion chamber 38 (i.e., the tube outlets 88). In specific embodiments, these combustion instability frequencies can be adjusted and / or tuned within one or more tubes 36 and / or tube bundles 62 to influence the combustion dynamics associated with the individual burner 14. In the Fig. 6 and Fig. For example, in the specific embodiment illustrated in Figure 9, the tubes 36 may have a different axial spacing 96 between the fuel injectors 94 and the combustion chamber 38 for each tube bundle 62. As a result, the combustion instability frequency for each tube 42 is slightly different, which reduces or prevents constructive interference between the tube bundles 62 from increasing the amplitude of the combustion dynamics associated with the particular combustor 14. Those skilled in the art will readily appreciate from the teachings herein that several combinations of variations in the axial spacings 96 between the fuel injectors 94 and the combustion chamber 38 are possible to achieve a desired combustion instability frequency for each tube 36 and / or tube bundle 62 and / or desired combustion dynamics for the particular combustor 14.For example, in particular embodiments, the axial distances 96 between the fuel injectors 94 and the combustion chamber 38 may be the same or different for some or all of the tubes 34 and / or tube bundles 62 in a particular combustor 14, and the present invention is not limited to any particular combination of axial distances 96 unless specifically recited in the claims.

[0030] The combustion dynamics associated with multiple burners 14 installed in the gas turbine 10 may, in turn, constructively or destructively interfere with each other to increase or decrease the amplitude and / or coherence of the combustion dynamics associated with the gas turbine 10. In specific embodiments, the combustion instability frequencies and / or combustion dynamics associated with one or more burners 14 may be adjusted and / or tuned to influence the interaction with the combustion dynamics of another burner 14 and thus the combustion dynamics associated with the gas turbine 10. For example, Fig. 10 shows a system for reducing combustion dynamics according to a second embodiment of the present invention. In the Fig. 10, several burners 14, as shown in the Fig. 5 and Fig. 9, arranged around an axis 100. The axis 100 may, for example, coincide with the rotor 18 in the gas turbine 10, which connects the compressor section 12 to the turbine section 16, although the present invention is not limited to the specific orientation of the axis 100 of the specific arrangement of combustors 14 about the axis 100.

[0031] According to the presentation in Fig. 10, each burner 14 includes a plurality of tubes 36 arranged in pie-shaped tube bundles 62 circumferentially surrounding the fuel nozzle 34, and the combustion chamber 38 is disposed downstream of the tubes 36, tube bundles 62, and the fuel nozzle 34 as described above with reference to FIG. Fig. 2, Fig. 5 and Fig. 9. In addition, the system further includes means for generating a combustion instability frequency in one burner 14 that differs from the combustion instability frequency in the other burner 14. The structure for the means may include a difference in one or more of the axial distances 96 between the fuel injectors 94 and the combustion chamber 38 between the two burners 14. In the Fig. For example, in the specific embodiment illustrated in Figure 10, the axial distance 96 between the fuel injectors 94 and the combustion chamber 38 is different for each tube bundle 62 between two burners 14. Accordingly, the device produces different combustion instability frequencies in the two burners 14. Those skilled in the art will readily appreciate from the teachings herein that several combinations of variations in the axial distances 96 between the fuel injectors 94 and the combustion chamber 38 are possible to produce a desired combustion instability frequency in one burner 14 that is different from the combustion instability frequency in the other burner 14.For example, in particular embodiments, one or more axial distances 96 between the fuel injectors 94 and the combustion chamber 38 may be the same or different for one or more of the tubes 36 and / or tube bundles 62 in a particular combustor 14 compared to the other combustor 14, as long as the axial distances 96 are not all the same between two combustors 14, and the present invention is not limited to any particular combination of axial distances 96 unless specifically recited in the claims.

[0032] Fig. 11 provides a system for reducing combustion dynamics according to an embodiment that is not part of the claimed invention. As shown in Fig. 11, each burner 14 in turn includes a plurality of tubes 36 arranged in pie-shaped bundles 62 circumferentially surrounding the fuel nozzle 34, and the combustion chamber 38 is disposed downstream of the tubes 36, tube bundles 62, and the fuel nozzle 34 as described above with reference to the Fig. 2, Fig. 5, Fig. 9 and Fig. 10. In addition, the axial positions of the fuel injectors 94 in each burner 14 may be different. In the Fig. For example, in the specific embodiment illustrated in Figure 11, the axial positions of the fuel injectors 94 for each tube bundle 62 within the same combustor 14 are different, but the axial positions of the fuel injectors 94 for each tube bundle 62 are repeated in both combustors 14.

[0033] The Fig. The embodiment shown in Figure 11 again includes means for generating a combustion instability frequency or resonance frequency in one burner 14 that is different from the combustion instability frequency or resonance frequency in the other burner 14. As in the embodiment shown in Fig. 8, the design for the device may include a difference in an axial length 80 of the cap assembly 50 in one burner 14 compared to the axial length 80 of the cap assembly in the other burner 14. With the axial positions of the fuel injectors 94 repeated in both burners 14, the difference in the axial lengths 80 between the two burners 14 creates a corresponding difference in the axial distances 96 between the fuel injectors 94 and the combustion chamber 38 between the two burners 14. The difference in the axial distances 96 between the two burners 14 creates a corresponding difference in the combustion instability or resonant frequencies between the two burners 14.One skilled in the art will readily appreciate from the teachings herein that several combinations of variations in the axial distances 96 between the fuel injectors 94 and the combustion chamber 38 are possible to create a combustion instability or resonant frequency in one combustor 14 that differs from the combustion instability or resonant frequency in the other combustor 14. For example, in particular embodiments, one or more axial distances 76 between the fuel inlets 74 and the combustion chamber 38 and / or the vanes 72 and the combustion chamber 38 may be the same or different for one or more of the fuel nozzles 34 in a particular combustor 14 compared to the other combustor 14, and the present invention is not limited to any particular combination of axial distances 76 unless specifically recited in the claims.

[0034] Fig. Figure 12 illustrates an exemplary graph for burner dynamics according to various embodiments of the present invention. The horizontal axis represents a range of combustion instability or resonant frequencies, and the vertical axis represents a range of amplitudes. Fig. The system illustrated in Figure 12 may include three or more burners 14 incorporated into a gas turbine 10 or other turbomachine. Using the means for generating a combustion instability frequency in one burner 14 that is different from the combustion instability frequency in the other burner 14, each burner 14 may be adjusted or tuned to achieve a desired combustion instability frequency or combustion dynamics. As illustrated in Fig. 12, for example, a first group of burners 14 may be adjusted and / or tuned to obtain a first combustion instability frequency 102, a second group of burners 14 may be adjusted and / or tuned to obtain a second combustion instability frequency 104, and a third group of burners 14 may be adjusted and / or tuned to obtain a third combustion instability frequency 106. The first, second, and third combustion instability frequencies 102, 104, 106 are slightly different from one another and are therefore slightly out of phase with one another. As a result, the combustion instability frequencies 102, 104, 106 associated with the burners 14 may incoherently or constructively interfere with one another, reducing or preventing an increase in combustion dynamics and / or reducing the ability of the combustion system to drive resonant frequencies in the downstream turbine section 16.

[0035] A person skilled in the art will readily recognize from the teachings herein that the invention described with reference to the Fig. 1-11 may provide one or more methods for reducing combustion dynamics and / or reducing the coherence of combustion dynamics for two or more combustors 14. The methods may include, for example, flowing the working fluid 92 and fuel through one or more fuel nozzles 34, tubes 36, and / or tube bundles 62 into the combustion chambers 38 of a plurality of combustors 14. In particular embodiments, the method may include varying one or more of the axial distances 76 between the fuel inlets 74 and the combustion chambers 38 and / or the vanes 72 and the combustion chamber 38, so long as the axial distances 76 are not all the same between all combustors 14, to create a combustion instability frequency in one combustor 14 that is different from the combustion instability frequency in the other combustors 14.In further specific embodiments, the method may include varying one or more of the axial distances 96 between the fuel injectors 94 and the combustion chamber 38, as long as the axial distances 96 are not all the same between all the burners 14, to create a combustion instability frequency in one burner 14 that is different from the combustion instability frequency in the other burner 14. In yet another specific embodiment, the method may include varying one or more axial lengths 80 of the cap assembly 50, as long as the axial lengths 80 are not all the same between all the burners 14, to create a combustion instability frequency in one burner 14 that is different from the combustion instability frequency in the other burner 14.

[0036] The provisions of the Fig.The various embodiments described and illustrated in Figures 1-12 may provide one or more of the following advantages over existing burners 14. In particular, the different axial spacings 76, 96, and / or axial lengths 80, alone or in various combinations, may decouple combustion instability frequencies from combustion dynamics. Accordingly, the various embodiments described herein may improve thermodynamic efficiency, promote flame stability, and / or reduce undesirable emissions over a wide range of operating conditions.

[0037] This description uses examples to disclose the invention, including its best mode, and to enable any person skilled in the art to practice the invention, including making and using all elements and systems and performing all incorporated methods. The patentable scope of the invention is defined by the claims and may include other examples that would be apparent to one skilled in the art. Such other examples are intended to be included within the scope of the invention if they contain structural elements that do not differ from the language of the claims, or if they contain equivalent structural elements with insubstantial changes from the language of the claims. LIST OF REFERENCE SYMBOLS: 10 gas turbines 12 Compressor section 14 burners 16 Turbine section 18 Rotor 20 generators 22 Working fluid 24 stationary guide vanes 26 rotating blades 28 Compressor housing 30 Compressor discharge plenum 32 burner housing 34 fuel nozzles 36 pipes 38 Combustion chamber 40 transition channel 42 rotating blades 44 stationary guide vanes 46 End cover 48 headboard 50 cap arrangement 52 deployment 54 flow holes 56 impact sleeve 58 annular tube bundles 60 central tube bundle 62 pie-shaped tube bundles 64 axial midline 66 central body 68 Cover 70 annular passage 72 guiding elements 74 fuel inlets 76 axial distances 78 Axis 80 axial length of the cap assembly 82 upstream surface 84 downstream surface 86 Pipe inlet 88 Pipe outlet 90 Fuel collection room 92 Fuel line 94 Fuel injection system 96 axial distance 100 axle 102 first resonance frequency 104 second resonance frequency 106 third resonance frequency

Claims

[1] Gas turbine (10) comprising: a plurality of burners (14) arranged in a circular ring around an axial centerline of the gas turbine, the plurality of burners (14) comprising a first burner (14) and a second burner (14); wherein the first burner (14) comprises a plurality of annular tube bundles (58, 62) of fuel nozzles (34) arranged in a circular ring around a centerline of the first burner (14), each tube bundle (58, 62) including a fuel plenum (90) and a plurality of tubes (36) extending therethrough, each tube (36) having a tube inlet (86) upstream of the fuel plenum (90), a tube outlet (88) downstream of the fuel plenum (90), and a fuel injector (94) providing fluid communication between the fuel plenum (90) and the tube (36), the fuel injector (94) being arranged at a first axial distance (96) from the tube outlet (88), and each tube (36) having the same first axial distance (96); wherein the second burner (14) comprises a plurality of tube bundles (58, 62) of fuel nozzles (34) arranged in a circular ring around a centerline of the second burner (14), each tube bundle (58, 62) comprising a fuel plenum (90) and a plurality of tubes (36) extending therethrough, each tube (36) comprising a tube inlet (86) upstream of the fuel plenum (90), a tube outlet (88) downstream of the fuel plenum (90), and a fuel injector (84) providing fluid communication between the fuel plenum (90) and the tube (36), the fuel injector (94) being arranged in a first axial section (96) from the tube outlet (88), each tube (36) having the same first axial distance (96); and wherein the first axial distance (96) of one of the plurality of tube bundles (58, 62) of the first burner (14) differs from the first axial distance (96) of one of the plurality of tube bundles (58, 62) of the second burner (14). [2] The gas turbine (10) of claim 1, wherein the plurality of tube bundles (58, 62) of the first burner (14) comprise a first tube bundle (58, 62) and a second tube bundle (58, 62), the first axial spacing of the first tube bundle (58, 62) being different from the first axial portion (96) of the second tube bundle (58, 62). [3] The gas turbine (10) of claim 1, wherein the plurality of tube bundles (58, 62) of the second burner (14) comprise a first tube bundle (58, 62) and a second tube bundle (58, 62), the first axial spacing (96) of the first tube bundle (58, 62) being different from the first axial spacing (96) of the second tube bundle (58, 62). [4] The gas turbine (10) of claim 1, wherein each of the first and second burners (14) includes a central fuel nozzle (34) surrounded by the respective plurality of tube bundles (58, 62). [5] The gas turbine (10) of claim 4, wherein each central fuel nozzle (34) is a central tube bundle fuel nozzle (34). [6] The gas turbine (10) of claim 4, wherein each central fuel nozzle (34) of the first and second combustors (14) includes a center body (66), a cover (68) extending around a portion of the center body (66), and a plurality of vanes (72) extending from the center body (66) to the cover (68), the cover (68) defining an annular passage (70) therebetween. [7] The gas turbine (10) of claim 6, wherein the central fuel nozzle (34) of the first combustor (14) includes a first fuel inlet (74) through at least one of the plurality of vanes (72) at a first axial distance (76) from a combustion chamber (38) formed within the first combustor (14), and a second fuel inlet (74) through the center body (66) near a tip portion of the center body (66) at a second axial distance (76) from the combustion chamber (38), and the plurality of vanes (72) are disposed at a third axial distance (76) from the combustion chamber (38). [8] The gas turbine (10) of claim 7, wherein the central fuel nozzle (34) of the second combustor (14) includes a first fuel inlet (74) through at least one of the plurality of vanes (72) at a first axial distance (76) from a combustion chamber (38) formed within the second combustor (14), and a second fuel inlet through the center body (66) near a tip portion of the center body (66) at a second axial distance (76) from the combustion chamber (38), and the plurality of vanes (72) are disposed at a third axial distance (76) from the combustion chamber (38). [9] The gas turbine of claim 8, wherein the first axial distance (76) of the central fuel nozzle (34) of the first burner (14) is different from the first axial distance (76) of the central fuel nozzle (34) of the second burner (14); and / or wherein the second axial distance (76) of the central fuel nozzle (34) of the first burner (14) differs from the second axial distance (76) of the central fuel nozzle (34) of the second burner (14); and / or wherein the third axial distance (76) of the central fuel nozzle (34) of the first burner (14) differs from the third axial distance (76) of the central fuel nozzle (34) of the second burner (14). [10] The gas turbine (10) of claim 8, wherein the first and second burners (14) each include a cap assembly (50) circumferentially surrounding the plurality of tube bundles (58, 62) of fuel nozzles (34), each cap assembly (50) having an axial length (80), the axial length (80) of the cap assembly (50) in the first burner (14) being different from the axial length (80) of the cap assembly (50) in the second burner (14).

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