Systems and methods for influencing combustion dynamic frequencies

Abstract

A method for frequency separation in a gas turbine, the method comprising: Determining a natural frequency of a hot gas path component; Determining a combustion dynamic amplitude and / or frequency; and Modifying a compressor outlet temperature to separate the combustion dynamic frequency from the natural frequency of the hot gas path component; wherein modifying the compressor outlet temperature comprises adjusting an inlet heat bleed flow and / or adjusting the temperature of air entering a compressor (102).

Description

Area of ​​Revelation

[0001] Embodiments of the present disclosure relate generally to gas turbines and, more particularly, to systems and methods for influencing combustion dynamic frequencies. Background to the revelation

[0002] Combustion chambers are commonly used in industrial and commercial operations to ignite fuel to produce combustion gases at high temperatures and high pressures. For example, gas turbines or other turbomachinery usually contain one or more combustion chambers to generate power or thrust. A typical gas turbine used to generate electricity contains an axial-flow compressor at the front, several combustion chambers near the center, and a turbine at the rear. Ambient air enters the compressor as a working fluid, and the compressor imparts increasing kinetic energy to the working fluid to create a compressed working fluid in a highly energetic state.The compressed working fluid leaves the compressor and flows through one or more fuel injectors into the combustion chambers, where the compressed working fluid mixes with a fuel before being ignited to produce combustion gases at high temperature and pressure. The combustion gases flow to the turbine, where they expand to perform work. For example, expansion of the combustion gases in the turbine can rotate a shaft connected to a generator to generate electricity.

[0003] Under certain operating conditions, combustion dynamics at specific frequencies and with sufficiently in-phase and coherent amplitudes can induce undesirable resonant resonances in the turbine and / or other downstream components. This problem is typically addressed by tuning a combustor. However, tuning a combustor to protect the turbine blades can impose serious limitations on the combustor's operation and performance.

[0004] US 2004 / 0 011 020 A1 discloses a method and system for frequency separation in a gas turbine. The system includes a compressor, a combustor, a turbine, and a controller in communication therewith. The controller is configured to modify a compressor inlet air flow by adjusting compressor inlet guide vanes to separate a combustion dynamic frequency from a predetermined frequency.

[0005] Thus, there is still a continuous need to improve the ability to separate the combustion dynamic frequencies and the natural frequencies of turbine blades. Brief description of the subject matter of disclosure

[0006] Some or all of the above needs and / or problems may be addressed by certain embodiments of the present disclosure.

[0007] According to one embodiment, a method for frequency separation in a gas turbine is disclosed. The method includes determining a natural frequency of a hot gas path component. The method further includes determining a combustion dynamic amplitude and / or frequency. Furthermore, the method includes modifying a compressor outlet temperature to separate the combustion dynamic frequency from the natural frequency of the hot gas path component. Modifying the compressor outlet temperature includes adjusting an inlet heat bleed flow and / or adjusting the temperature of air entering a compressor.

[0008] The method may include determining the combustion dynamics amplitude and / or frequency comprising monitoring a combustion chamber with at least one dynamic pressure sensor.

[0009] Any method mentioned above may further comprise determining the compressor outlet temperature by monitoring the compressor with at least one temperature sensor.

[0010] Any method mentioned above may include modifying the compressor outlet temperature comprising adjusting one or more inlet guide vanes.

[0011] According to another embodiment, a system for frequency separation in a gas turbine is disclosed. The system includes a compressor, a combustor in communication with the compressor, and a turbine in communication with the compressor and the combustor. The system further includes a controller in communication with at least one of the compressor, the combustor, and / or the turbine. The controller is configured to modify a compressor outlet temperature to separate a combustion dynamic frequency from a natural frequency of a hot gas path component. The system further includes an inlet heat bleed flow associated with the compressor, the controller configured to adjust the inlet heat bleed flow for the compressor to modify the compressor outlet temperature.Alternatively or additionally, the control device is configured to adjust a temperature of air entering the compressor to modify the compressor outlet temperature.

[0012] The system may further include at least one dynamic pressure sensor associated with the combustion chamber and configured to monitor the combustion dynamic frequency.

[0013] Any system mentioned above may further include at least one temperature sensor associated with a compressor outlet and configured to monitor the compressor outlet temperature.

[0014] Any system mentioned above may further include one or more inlet guide vanes associated with the compressor, wherein the controller is configured to adjust the one or more inlet guide vanes to modify the compressor outlet temperature.

[0015] The natural frequency of the hot gas path component of any of the above-mentioned systems may have a single frequency or a range of frequencies.

[0016] The hot gas path component of any of the above-mentioned systems may include a turbine blade.

[0017] The combustion dynamic frequency of any of the above-mentioned systems may have a single frequency or a range of frequencies.

[0018] Further embodiments, aspects and features of the subject matter will become apparent to those skilled in the art from the following detailed description, the accompanying drawings and the appended claims. Brief description of the drawings

[0019] Reference is now made to the attached drawing, which is not necessarily drawn to scale. Fig. 1 shows a schematic representation of an example diagram of a gas turbine system configured to control combustion dynamic frequencies, according to one embodiment. Detailed description of the subject matter of disclosure

[0020] Illustrative embodiments are now described in greater detail below with reference to the accompanying drawings, in which some, but not all, embodiments are illustrated. The present disclosure may be embodied in many different forms and should not be construed as limited to the embodiments illustrated herein. Like reference numerals refer to like elements throughout.

[0021] Illustrative embodiments are directed, among other things, to systems and methods for frequency separation in a gas turbine. For example, in some embodiments, a combustion dynamic frequency may be actively separated (or shifted away) from a natural frequency of a hot gas path component by modifying a compressor outlet temperature. That is, the combustion dynamic frequencies associated with a combustor in a gas turbine may be modified by adjusting a compressor outlet temperature. In some cases, the combustion outlet temperature may be modified by adjusting one or more inlet guide vanes associated with a compressor. According to the invention, the compressor outlet temperature is modified by adjusting an inlet bleed heat associated with a compressor.Alternatively or additionally, the compressor outlet temperature is modified by adjusting the temperature of the air entering the compressor section through evaporative cooling, heat exchangers, or other temperature-modifying devices as known in the art. Furthermore, the compressor outlet temperature may be modified by a combination of adjusting one or more inlet guide vanes and / or adjusting the inlet bleed heat and / or adjusting the temperature of the air entering the compressor.

[0022] The natural frequency of a hot-gas path component may include a single frequency of interest or a range of frequencies of interest. In some cases, the hot-gas path component may be a turbine blade (such as a first-stage turbine blade) or another turbine component. The hot-gas path component may include any turbine component at any stage in the turbine. Similarly, the combustion dynamic frequency may include a single frequency of interest or a range of frequencies of interest.

[0023] As previously mentioned, the compressor outlet temperature may be adjusted by controlling an inlet guide vane angle and / or an inlet heat bleed flow to a compressor and / or adjusting the temperature of the air entering the compressor. For example, in some embodiments, a controller may be configured to monitor a frequency and amplitude of a combustor tone in real time using one or more dynamic pressure sensors or the like. In this way, active control may be realized by the controller to adjust the combustor frequency of interest in real time by separating it from (or shifting it from) a natural frequency of a hot gas path component.The combustor frequency of interest can be modified to maintain frequency separation between the turbine blades and the combustor while preventing unacceptable turbine blade response due to frequency overlap.

[0024] In some embodiments, the compressor outlet temperature can be adjusted to control combustion dynamic frequencies of interest to maintain separation from natural frequencies of hot gas path components. The role of compressor outlet temperature in influencing combustion dynamic frequencies is twofold. First, a change in the temperature of the air entering the combustion system changes the speed of sound and consequently the acoustic natural frequency of the combustor. Second, a change in compressor outlet temperature may be accompanied by or result from a change in airflow through the combustion chamber and therefore through the combustion system. A change in airflow through the combustion system affects the coupling between the heat release variation inherent in the combustion process and the acoustic resonant frequencies of the combustor.One particular mechanism known in the art to play a significant role in this coupling between heat release and combustor acoustic resonances occurs when acoustic pulsations driven by heat release fluctuations induce mass flow fluctuations through the fuel ports, which then cause the flame zone fuel / air ratio to fluctuate. When the resulting fuel / air ratio fluctuation and the acoustic pressure pulsations are in phase, a self-excited feedback loop results. This mechanism depends on the length of time it takes for the fuel / air ratio disturbance to reach the flame zone, known in the art as the convective time (tau), and is thus inversely proportional to the flow through the combustor.As the convective time increases, the frequency of combustion instability decreases, and as the convective time decreases, the frequency of combustion instability increases. Changing the compressor outlet temperature by altering the inlet guide vane, the inlet heat bleed flow, and / or the temperature of the air entering the compressor will consequently change the acoustic natural frequency and / or the convective time of the combustor. By shifting the combustion dynamic frequency away from the natural frequencies of hot gas path components, gas turbine operation can continue without the risk of damage to the turbine blades due to high-cycle fatigue.

[0025] It will now Fig. 1, which shows a schematic view of an exemplary embodiment of a gas turbine system 100, as may be used herein. For example, the gas turbine system 100 may include a compressor 102. The compressor 102 may compress an incoming air stream 104. The compressor 102 may deliver the compressed air stream 104 to a combustor 106. The combustor 106 may mix the compressed air stream 104 with a pressurized fuel stream 108 and ignite the mixture to produce a stream of combustion gases 110. Although only a single combustor 106 is illustrated, the gas turbine system 100 may include any number of combustors 106. The flow of combustion gases 110 may, in turn, be delivered to a turbine 112. The turbine 112 may include a number of blades 132 arranged in stages, such as stage 1, stage 2, stage 3, etc.The flow of combustion gases 110 can drive the rotor blades 132 within the turbine 112 to perform mechanical work. The mechanical work performed in the turbine 112 can drive the compressor 102 via a shaft 114 and an external load 116, such as an electric generator or the like.

[0026] The gas turbine system 100 may utilize natural gas, various types of syngas, and / or other fuel types. The gas turbine system 100 may have different configurations and may utilize different types of components. Furthermore, other types of gas turbines may also be used herein. Multiple gas turbines, other types of turbines, or other types of power generation equipment may also be used together herein.

[0027] Further referring to Fig.1, the gas turbine system 100 may include an inlet heat bleed system 120 associated with the compressor 102. The inlet heat bleed system 120 may be configured to exhaust hot air from a rear portion of the compressor 102 and then supply the hot air back to the compressor 102 for recirculation therethrough. In some embodiments, the inlet heat bleed system 120 may include a valve 124 or other control device for regulating the inlet heat bleed system 120. The amount of inlet heat bleed may have an impact on the compressor outlet temperature and / or the flow rate of air through the compressor.

[0028] In some embodiments, gas turbine system 100 may include an inlet guide vane system 118 associated with compressor 102. Inlet guide vane system 118 may include a number of fixed and / or adjustable vanes therein. The angle of the inlet guide vanes may affect the compressor outlet temperature and / or the air flow rate through the compressor.

[0029] In some embodiments, the gas turbine system 100 may include one or more sensors positioned at various locations on the gas turbine system 100. The sensors may be associated with various components of the gas turbine system 100 for monitoring them. For example, a dynamic pressure sensor 128 may be associated with the combustor 106 to monitor a combustion dynamic frequency and combustion dynamic amplitude of the combustor 106. A temperature sensor 130 may be positioned downstream of the compressor 102 to monitor a compressor outlet temperature and / or a combustor inlet temperature. An accelerometer, strain gauge, or optical sensor 134 may be associated with the turbine 112, such as a first-stage blade 132, to monitor the vibration response of the blade 132. Other sensors may also be used.The sensors may be of conventional design. Other types of operating parameters may be monitored therein. Furthermore, any stage in the turbine 112 may be monitored.

[0030] In some embodiments, the gas turbine system 100 may include one or more controllers 122 in communication with the various components of the gas turbine system 100 for monitoring and / or controlling them. For example, the controller 122 may be in communication with, among others, the compressor 102, the combustor 106, the turbine 112, the inlet guide vane system 118, the valve 124 of the inlet bleed system 120, the temperature sensor 130, the dynamic pressure sensor 128, and / or the vibration sensor 134, etc. The controller 122 may include at least one memory 123 and one or more processing units (or processors) 126. The processors 126 may be implemented in hardware, software, firmware, or combinations thereof, as appropriate.Software or firmware implementations of processors 126 may include computer-executable or machine-executable instructions written in any suitable programming language to perform the various described functions. Furthermore, processors 126 may be associated with a network, a server, a computer, or a mobile device.

[0031] In some cases, the controller 122 may be configured to actively separate (or shift) a combustion dynamic frequency from a natural frequency of a hot gas path component by controlling a compressor outlet temperature. In some cases, the hot gas path component may be a first stage blade 132, although any blade stage may be used herein. For example, the controller 122 may be configured to determine, predict, monitor, identify, or the like a hot gas path component response amplitude and / or frequency, a combustion dynamic amplitude and / or frequency, and / or a compressor outlet temperature. The controller may further be configured to separate (or shift) the combustion dynamic frequency from the natural frequency of the hot gas path component by controlling the compressor outlet temperature.For example, the compressor outlet temperature can be influenced by adjusting the angle of the inlet guide vanes 118 associated with the compressor 102, by adjusting the inlet heat extraction system 120 associated with the compressor 102, by adjusting the temperature of the air entering the compressor, or by a combination of these. For example, the controller can open or close the valve 124 to increase or decrease the inlet heat extraction.

[0032] The algorithms associated with controller 122 for separating (or shifting) the combustion frequency can vary considerably and depend, among other things, on the combustion architecture. Although embodiments are described in language specific to structural features and / or methodological acts, it is understood that the disclosure is not necessarily limited to the specific features or acts described. Rather, the specific features and acts are disclosed as illustrative forms of implementing the embodiments.

[0033] Systems and methods for frequency separation in a gas turbine are provided herein. The systems and methods for frequency separation in a gas turbine may include determining a natural frequency of a hot gas path component, determining a combustion dynamic frequency, and modifying a compressor outlet temperature to separate the combustion dynamic frequency from the natural frequency of the hot gas path component.

Claims

[1] A method for frequency separation in a gas turbine, the method comprising: Determining a natural frequency of a hot gas path component; Determining a combustion dynamic amplitude and / or frequency; and Modifying a compressor outlet temperature to separate the combustion dynamic frequency from the natural frequency of the hot gas path component; wherein modifying the compressor outlet temperature comprises adjusting an inlet heat bleed flow and / or adjusting the temperature of air entering a compressor (102). [2] The method of claim 1, wherein determining the combustion dynamics amplitude and / or frequency comprises monitoring a combustion chamber (106) with at least one dynamic pressure sensor (128). [3] The method of claim 1, further comprising determining the compressor outlet temperature by monitoring the compressor (102) with at least one temperature sensor (130). [4] The method of claim 1, wherein modifying the compressor outlet temperature comprises adjusting one or more inlet guide vanes. [5] A system for frequency separation in a gas turbine, the system comprising: a compressor (102); a combustion chamber (106) in communication with the compressor (102); a turbine (112) in communication with the compressor (102) and the combustion chamber (106); and a controller (122) in communication with at least one of the compressor (102), the combustor (106), and / or the turbine (122), the controller (122) configured to modify a compressor outlet temperature to separate a combustion dynamic frequency from a natural frequency of a hot gas path component; wherein the system further comprises an inlet heat bleed flow associated with the compressor (102), wherein the controller (122) is configured to adjust the inlet heat bleed flow for the compressor (102) to modify the compressor outlet temperature; and / or wherein the controller (122) is configured to adjust a temperature of air entering the compressor (102) to modify the compressor outlet temperature. [6] The system of claim 5, further comprising at least one dynamic pressure sensor (128) associated with the combustor (106) and configured to monitor the combustion dynamic frequency; and / or further comprising at least one temperature sensor (130) associated with a compressor outlet and configured to monitor the compressor outlet temperature. [7] The system of claim 5 or 6, further comprising one or more inlet guide vanes associated with the compressor, wherein the controller (122) is configured to adjust the one or more inlet guide vanes to modify the compressor outlet temperature. [8] The system of claim 5, wherein the natural frequency of the hot gas path component comprises a single frequency or a range of frequencies; and / or wherein the hot gas path component comprises a turbine blade (132). [9] The system of claim 5, wherein the combustion dynamic frequency comprises a single frequency or a range of frequencies.

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