SYSTEM AND METHOD FOR DETERMINING A FLAME CONDITION IN A COMBUSTOR

Abstract

A system for determining a flame condition in a combustor includes a pressure sensor that generates a pressure signal reflective of a pressure in the combustor. A controller receives the pressure signal and generates a flame signal reflective of the flame condition in the combustor. A method for determining a flame condition in a combustor includes measuring a pressure in the combustor, comparing the measured pressure in the combustor to a predetermined limit, and generating a flame signal based on the comparison of the measured pressure in the combustor to the predetermined limit, wherein the flame signal reflects the flame condition in the combustor.

Description

FIELD OF THE INVENTION

The present invention generally involves a system and method for determining a flame condition in a combustor. Specifically, particular embodiments of the present invention monitor pressure in the combustor to determine the presence and/or absence of a flame in the combustor.

BACKGROUND OF THE INVENTION

Combustors are known in the art for igniting fuel with air to produce combustion gases having high temperature and pressure. For example, gas turbine systems typically include multiple combustors that mix a compressed working fluid from a compressor with fuel and ignite the mixture to produce high temperature and pressure combustion gases. During initial light-off of a combustor, it is generally desirable to create and maintain a stable flame in the combustor immediately prior to or shortly after introducing fuel into the combustor to initiate and maintain combustion in the combustor. During steady-state and transient operations, the fuel-air mixture is constantly being adjusted to optimize thermodynamic efficiency and reduce undesirable emissions of nitrous oxide, carbon monoxide, and other combustion byproduct gases. The adjustments to the fuel-air mixture may create instabilities in the flame that may lead to a blowout or loss of flame condition in the combustor, thus interrupting continuity of the combustion process. In either instance, it is desirable to detect and monitor the flame condition in the combustor to ensure safe and continuous operation of the combustor.

Various systems are known in the art for detecting and/or monitoring the flame condition in the combustor. For example, optical sensors that detect light, ultraviolet, or other emissions produced by a combustion flame may be used to determine the flame condition in the combustor. Optical sensors, however, typically require some form of cooling which has a tendency to interfere with the efficiency and operation of the combustor and/or downstream components. Temperature detectors in or downstream of the combustor may also be used to detect and monitor the flame condition in the combustor. However, the response time of temperature detectors is typically too slow to provide a timely response to sudden changes in the flame condition in the combustor. As a result, an improved system and method for determining the flame condition in a combustor would be useful.

BRIEF DESCRIPTION OF THE INVENTION

Aspects and advantages of the invention are set forth below in the following description, or may be obvious from the description, or may be learned through practice of the invention.

One embodiment of the present invention is a system for determining a flame condition in a combustor. The system includes a pressure sensor that generates a pressure signal reflective of a pressure in the combustor. A controller receives the pressure signal from the pressure sensor and generates a flame signal reflective of the flame condition in the combustor.

Another embodiment of the present invention is a system for determining a flame condition in a combustor. The system includes a pressure sensor that generates a series of time indexed pressure signals reflective of pressures in the combustor at different times. A controller receives the time indexed pressure signals from the pressure sensor and generates a flame signal reflective of the flame condition in the combustor.

Embodiments of the present invention may also provide a method for determining a flame condition in a combustor. The method includes measuring a pressure in the combustor, comparing the measured pressure in the combustor to a predetermined limit, and generating a flame signal based on the comparison of the measured pressure in the combustor to the predetermined limit, wherein the flame signal reflects the flame condition in the combustor.

Those of ordinary skill in the art will better appreciate the features and aspects of such embodiments, and others, upon review of the specification.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including the best mode thereof to one skilled in the art, is set forth more particularly in the remainder of the specification, including reference to the accompanying figures, in which:

FIG. 1 is a simplified block diagram of a system according to one embodiment of the present invention;

FIG. 2 is a block diagram of an algorithm according to one embodiment of the present invention;

FIG. 3 is an exemplary graph of pressure in each of 14 different combustors;

FIG. 4 is a block diagram of an algorithm according to an alternate embodiment of the present invention; and

FIG. 5 is an exemplary time-pressure graph for a combustor.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to present embodiments of the invention, one or more examples of which are illustrated in the accompanying drawings. The detailed description uses numerical and letter designations to refer to features in the drawings. Like or similar designations in the drawings and description have been used to refer to like or similar parts of the invention.

Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that modifications and variations can be made in the present invention without departing from the scope or spirit thereof. For instance, features illustrated or described as part of one embodiment may be used on another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents.

Various embodiments of the present invention provide a system and method for determining a flame condition in a combustor. As used herein, the “flame condition” is defined to mean the presence, absence, and/or stability of a flame in the combustor. Specifically, embodiments of the present invention may sense and measure pressure, pressure changes, and/or the rate of pressure changes in the combustor to determine the flame condition in the combustor. As a result, embodiments of the present invention may provide a redundant, reliable, and/or replacement system and method for monitoring the flame condition in a combustor to improve the overall reliability and performance of the combustor. Although exemplary embodiments of the present invention are discussed in the context of a combustor incorporated in a gas turbine system, one of ordinary skill in the art will readily appreciate that the teachings of the present invention may be applicable to any system or method that involves the combustion of fuel, and the scope of the present invention is not limited to any particular combustor application unless specifically recited in the claims.

FIG. 1 provides a simplified block diagram of a system 10 in the context of a gas turbine system 12 according to one embodiment of the present invention. As is known in the art, the gas turbine system 12 generally includes an axial compressor 14 at the front, one or more combustors 16 around the middle, and a turbine 18 at the rear. Ambient air 20 enters the compressor 14, and rotating blades and stationary vanes in the compressor 14 progressively impart kinetic energy to the air to produce a compressed working fluid 22 at a highly energized state. As shown in FIG. 1, the compressor 14 may include an inlet guide vane 24 that may be adjustable to control or regulate the amount of ambient air 20 that enters the compressor 14, thus controlling the mass flow rate and/or pressure of the compressed working fluid 22 exiting the compressor 14. The compressed working fluid 22 exits the compressor 14 and flows into the combustors 16 where it mixes with fuel supplied by a fuel system 26. The mixture ignites to generate combustion gases 28 having a high temperature and pressure. The combustion gases 28 expand in the turbine 18 to produce work. For example, expansion of the combustion gases 28 in the turbine 18 may rotate a shaft 30 connected to a generator 32 to produce electricity.

In the embodiment shown in FIG. 1, the system 10 generally includes a pressure sensor 34 and a controller 36 operatively connected to the gas turbine system 12 to determine the flame condition in one or more combustors 16. The pressure sensor 34 may comprise any suitable instrument known in the art for detecting and measuring pressure in the combustor 16 and generating one or more pressure signals 38 reflective of the pressure in the combustor 16. The controller 36 receives the one or more pressure signals 38 from each pressure sensor 34 and generates a flame signal 40 reflective of the flame condition in each combustor 16.

The controller 36 may be a stand alone component or a sub-component included in any computer system known in the art, such as a laptop, a personal computer, a mini computer, a mainframe computer, or industrial controllers, microcontrollers, or embedded systems. The various controller and computer systems discussed herein are not limited to any particular hardware architecture or configuration. Embodiments of the systems and methods set forth herein may be implemented by one or more general-purpose or customized controllers adapted in any suitable manner to provide the desired functionality. The controller 36 may be adapted to provide additional functionality, either complementary or unrelated to the present subject matter. For instance, one or more controllers may be adapted to provide the described functionality by accessing software instructions rendered in a computer-readable form. When software is used, any suitable programming, scripting, or other type of language or combinations of languages may be used to implement the teachings contained herein. However, software need not be used exclusively, or at all. For example, as will be understood by those of ordinary skill in the art without required additional detailed discussion, some systems and methods set the forth and disclosed herein may also be implemented by hard-wired logic or other circuitry, including, but not limited to, application-specific circuits. Of course, various combinations of computer-executed software and hard-wired logic or other circuitry may be suitable as well.

The pressure sensor 34 and the controller 36 may operate intermittently, continuously, and/or when directed by an operator. For example, FIG. 2 provides a block diagram of an algorithm that may be programmed, hardwired, or otherwise implemented by the controller 36 to determine the flame condition in the combustor 16. Block 50 represents the activation of the flame detection system 10. The activation may be manually or automatically directed. For example, during an initial combustor 16 light-off, an operator may manually activate the flame detection system 10 to assist in determining when ignition occurs in the combustor 16. Alternately, following a blowout or loss of flame condition in a combustor 16, a protective or corrective system may automatically activate the flame detection system 10 to monitor the relight of the flame in the combustor 16.

At block 52, the system 10 may energize an igniter 54 operatively connected to the combustor 16 to provide a spark, pilot light, laser beam, or other ignition source for the combustor 16. In addition, at block 52 the pressure sensor 34 begins measuring the pressure in the combustor 16 and generating one or more pressure signals 38 to the controller 36.

At block 56, the controller 36 compares the one or more pressure signals 38 to a predetermined limit to determine the flame condition in the combustor 16. The predetermined limit provides an indication of the presence or absence of a flame in the combustor 16 and may be established by calculations, operational experience, modeling, or other methods known in the art. For example, although the instantaneous pressure in each combustor 16 may vary substantially over relatively short time intervals, an instantaneous pressure in any combustor 16 may be reliably used to indicate the presence or absence of a flame in an individual combustor 16. To illustrate this, FIG. 3 shows an exemplary graph of the instantaneous pressure in each of 14 different combustors 16 in the gas turbine system 12. As shown in FIG. 3, the instantaneous pressure in combustor number 11 is significantly below the instantaneous pressure in any other combustor, thus indicating a loss or lack of flame in combustor number 11. One of ordinary skill in the art will readily appreciate that the predetermined limit is not necessarily limited to instantaneous pressure. For example, the predetermined limit in alternate embodiments may be a change in pressure, a rate of change in pressure, and/or another calculation or derivative of pressure in the combustor 16 that indicates the presence or absence of a flame in the combustor 16.

The controller 36 generates the flame signal 40 reflective of the flame condition in the combustor 16 based on the comparison between the one or more pressure signals 38 and the predetermined limit. For example, if the comparison between the one or more pressure signals 38 and the predetermined limit indicates the presence of a flame in the combustor 16, then the controller 36 may send the flame signal 40 to the igniter 54 to de-energize the igniter 54 and/or de-activate the flame detection system 10, as represented by block 58. Alternately, if the comparison between the one or more pressure signals 38 and the predetermined limit indicates the absence of a flame in the combustor 16, then the flame signal 40 may cause the igniter 54 to remain energized.

As shown by block 60 in FIG. 2, the algorithm may further include a predetermined time limit. For example, if the comparison between the one or more pressure signals 38 indicates the absence of a flame in the combustor 16, and the predetermined time limit is not exceeded, the flame signal 40 may cause the igniter 54 to remain energized. However, if the predetermined time limit is exceeded, indicating an inability to ignite the combustor 16 within the predetermined time period, the controller 36 may generate a signal to de-energize the igniter 54 and/or the flame detection system 10 and/or increase or decrease the fuel flow to the combustor 16, as represented by block 58.

FIG. 4 provides a block diagram of another example of an algorithm that may be programmed, hardwired, or otherwise implemented by the controller 36 to determine the flame condition in the combustor 16 and/or respond to an anticipated change in the flame condition. Block 70 represents the activation of the flame detection system 10. As with the embodiment previously described and illustrated with respect to FIG. 2, the activation may be manually or automatically directed. For example, an operator may manually activate the flame detection system 10 during transient operations to more closely monitor the flame condition to avoid an inadvertent blowout or loss of flame in the combustor 16. Alternately, a protective or corrective system may automatically activate the flame detection system 10 during transient operations to more closely monitor the flame condition.

At block 72, the pressure sensor 34 again begins measuring the pressure in the combustor 16 and generating one or more pressure signals 38 to the controller 36. In this particular embodiment, the pressure signals 38 may be time indexed to provide a continuous stream of pressure signals reflective of pressures in the combustor 16 at different times. Depending on the particular embodiment, the system 10 may also energize the igniter 54 operatively connected to the combustor 16 to provide a spark, pilot light, laser beam, or other ignition source for the combustor 16.

At block 74, the controller 36 compares the one or more pressure signals 38 to a predetermined profile, such as a profile of pressure over a time interval, to determine the flame condition in the combustor 16. The predetermined profile provides an indication of the presence or absence of conditions that may lead to or reliably serve as a precursor to a blowout or loss of flame condition in the combustor 16 during transient operations. The predetermined profile may be developed by calculations, operational experience, modeling, or other methods known in the art. For example, individual combustors may exhibit distinctive, repeatable, and observable changes in pressure over a time interval that may be used to predict or anticipate a blowout or loss of flame condition in the combustor. To illustrate this, FIG. 5 shows an exemplary pressure profile 76 of a combustor during a blowout condition 78 and a subsequent re-light 80 of the combustor. As shown in FIG. 5, the pressure profile 76 illustrates a distinctive pressure, change in pressure, and/or rate of change in pressure in the combustor 16 during the blowout condition 78 and the subsequent re-light 80 of the combustor. The controller 36 may thus compare the time indexed pressure signals 38 to this predetermined profile to generate the flame signal 40 reflective of the flame condition in the combustor 16. One of ordinary skill in the art will readily appreciate that the predetermined profile is not necessarily limited to a single calculation or derivative of pressure in the combustor 16, and the predetermined profile may comprise a combination of multiple calculations or derivatives of pressure in the combustor 16. For a example, the predetermined profile in alternate embodiments may be a combination of individual profiles of time indexed pressures, time indexed changes in pressures, time indexed rates of change in pressures, and/or other calculations or derivatives of pressure in the combustor 16 that may be reliably used as precursors to a blowout or loss of flame condition in the combustor 16.

Returning to FIG. 4, block 82 represents that the system 10 may further use the flame signal 40 to adjust various parameters in the gas turbine system 12 to avoid a blowout or loss of flame condition in the combustor 16. For example, as previously described with respect to the embodiment shown in FIGS. 1 and 2, the igniter 54 may receive the flame signal 40 to energize the igniter 54 and provide an immediate ignition source for relighting the flame in the combustor 16. Alternately, or in addition, the controller 36 may transmit the flame signal 40 to the compressor 14 to change the position of the inlet guide vane 24, to the fuel system 26 to change the amount of fuel supplied to the combustor 16, and/or to the generator 32 to change the load on the turbine 18. The system 10 may take each of these actions individually or in combination in response to the flame signal 40 to stabilize the flame in the combustor 16 during transient operations that may otherwise result in a blowout or loss of flame condition in the combustor 16.

It is anticipated that embodiments of the present invention provide several benefits over existing technology. For example, the system 10 and methods described with respect to FIGS. 1-5 may be used to supplement and/or replace existing optical and thermal sensors used to determine the flame condition in a combustor. In addition, embodiments of the present invention may be used to detect conditions or precursors that may lead to instability in the flame condition, and in particular embodiments, the system 10 may take appropriate action to remove or correct the conditions or precursors to ensure continuity in the combustion process.

This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other and examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.

Claims

1. A system for determining a flame condition in a combustor comprising:

a. a pressure sensor, wherein said pressure sensor generates a pressure signal reflective of a pressure in the combustor;

b. a controller, wherein said controller receives said pressure signal from said pressure sensor and generates a flame signal reflective of the flame condition in the combustor.

2. The system as in claim 1, wherein said controller compares said pressure signal to a predetermined limit.

3. The system as in claim 2, wherein said predetermined limit comprises a predetermined pressure.

4. The system as in claim 1, wherein said pressure sensor generates a plurality of pressure signals to said controller, wherein each of said plurality of pressure signals reflects the pressure in the combustor at a different time.

5. The system as in claim 4, wherein said controller receives said plurality of pressure signals from said pressure sensor and generates said flame signal reflective of the flame condition in the combustor.

6. The system as in claim 4, wherein said controller compares said plurality of pressure signals to a predetermined profile.

7. The system as in claim 6, wherein said predetermined profile comprises a predetermined pressure profile.

8. The system as in claim 1, further comprising an igniter that receives said flame signal.

9. A system for determining a flame condition in a combustor comprising:

a. a pressure sensor, wherein said pressure sensor generates a series of time indexed pressure signals reflective of pressures in the combustor at different times;

b. a controller, wherein said controller receives said time indexed pressure signals from said pressure sensor and generates a flame signal reflective of the flame condition in the combustor.

10. The system as in claim 9, wherein said controller compares said time indexed pressure signals to a predetermined profile.

11. The system as in claim 10, wherein said predetermined profile comprises a predetermined pressure profile.

12. The system as in claim 9, further comprising an igniter that receives said flame signal.

13. A method for determining a flame condition in a combustor comprising:

a. measuring a pressure in the combustor;

b. comparing the measured pressure in the combustor to a predetermined limit;

c. generating a flame signal based on the comparison of the measured pressure in the combustor to the predetermined limit, wherein the flame signal reflects the flame condition in the combustor.

14. The method as in claim 13, further comprising transmitting the flame signal to an igniter.

15. The method as in claim 13, further comprising transmitting the flame signal to a compressor.

16. The method as in claim 13, further comprising transmitting the flame signal to a fuel system.

17. The method as in claim 13, further comprising transmitting the flame signal to a generator.

18. The method as in claim 13, further comprising measuring a plurality of pressures in the combustor at different times.

19. The method as in claim 18, further comprising generating the flame signal based on the plurality of measured pressures in the combustor, wherein the flame signal is reflective of the flame condition in the combustor.

20. The method as in claim 18, further comprising comparing the plurality of pressures to a predetermined profile.