U.S. patent application number 15/128283 was filed with the patent office on 2018-06-21 for method for optimizing base points used in temperature mapping of a turbine hot gas flow path by determining acoustic signal intersection points.
The applicant listed for this patent is Siemens Energy, Inc.. Invention is credited to Heiko Claussen, Upul P. DeSilva, Karthik Ragunathan.
Application Number | 20180172555 15/128283 |
Document ID | / |
Family ID | 54068560 |
Filed Date | 2018-06-21 |
United States Patent
Application |
20180172555 |
Kind Code |
A1 |
DeSilva; Upul P. ; et
al. |
June 21, 2018 |
METHOD FOR OPTIMIZING BASE POINTS USED IN TEMPERATURE MAPPING OF A
TURBINE HOT GAS FLOW PATH BY DETERMINING ACOUSTIC SIGNAL
INTERSECTION POINTS
Abstract
A method for optimizing base points each used in a corresponding
basis function utilized in generating a parameter map for a hot gas
flow path constrained by a boundary. The method includes providing
a plurality of transceivers, wherein each transceiver generates an
acoustic signal that travels through a measurement space in the hot
gas flow path and wherein each acoustic signal defines an acoustic
path. The method also includes locating the transceivers such that
the acoustic paths travel through a region of interest in the
measurement space. In addition, an average temperature for each
acoustic path is determined. Next, at least one base point in the
measurement space is determined. Further, the method includes
providing a basis function for each base point and generating a
weight of each basis function.
Inventors: |
DeSilva; Upul P.; (Oviedo,
FL) ; Claussen; Heiko; (North Brunswick, NJ) ;
Ragunathan; Karthik; (Bangalore, IN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Siemens Energy, Inc. |
Orlando |
FL |
US |
|
|
Family ID: |
54068560 |
Appl. No.: |
15/128283 |
Filed: |
April 22, 2015 |
PCT Filed: |
April 22, 2015 |
PCT NO: |
PCT/US2015/027020 |
371 Date: |
September 22, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14682393 |
Apr 9, 2015 |
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15128283 |
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14207803 |
Mar 13, 2014 |
9556791 |
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14682393 |
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61983044 |
Apr 23, 2014 |
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61983044 |
Apr 23, 2014 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G01F 1/668 20130101;
G01K 13/02 20130101; G01K 2013/024 20130101; G01M 15/14 20130101;
G01K 2213/00 20130101; G01K 11/24 20130101 |
International
Class: |
G01M 15/14 20060101
G01M015/14; G01K 13/02 20060101 G01K013/02; G01K 11/24 20060101
G01K011/24; G01F 1/66 20060101 G01F001/66 |
Goverment Interests
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0002] Temperature mapping portions of this invention were made
with government support under contract DE-FC26-05NT42644 awarded by
the U.S. Department of Energy. The government may have certain
rights in the invention.
Claims
1. A method for optimizing base points each used in a corresponding
basis function utilized in generating a parameter map for a hot gas
flow path constrained by a boundary, comprising: providing a
plurality of transceivers, wherein each transceiver generates an
acoustic signal that travels through a measurement space in the hot
gas flow path and wherein each acoustic signal defines an acoustic
path; determining an average temperature for each acoustic path;
determining at least one base point in the measurement space;
providing a basis function for each base point; and generating a
weight of each basis function.
2. The method according to claim 1, wherein a constraint includes
setting a maximum and minimum temperature for each weight.
3. The method according to claim 1, wherein a constraint includes
minimizing differences in weighting of basis functions of
relatively close seat points.
4. The method according to claim 1, wherein an objective is to
minimize line fit error relative to each average temperature.
5. The method according to claim 1, further including determining
intersection points of each acoustic path, wherein each
intersection point corresponds to a base point.
6. The method according to claim 1, wherein uniformly spaced base
points are added for defining known boundary conditions.
7. The method according to claim 1, further including locating the
transceivers so as to increase acoustic path density in a region of
interest in the measurement space to thereby increase a number of
base points in the measurement space.
8. The method according to claim 1, wherein the basis function is
selected from the group consisting of Gaussian, subgaussian,
supergaussian and spline basis functions.
9. The method according to claim 1, wherein the basis function is a
combined basis function that includes more than one type of basis
function.
10. A method for optimizing base points each used in a
corresponding basis function utilized in generating a parameter map
for a hot gas flow path constrained by a boundary, comprising:
providing a plurality of transceivers, wherein each transceiver
generates an acoustic signal that travels through a measurement
space in the hot gas flow path and wherein each acoustic signal
defines an acoustic path; locating the transceivers such that the
acoustic paths travel through a region of interest in the
measurement space; determining an average temperature for each
acoustic path; determining at least one base point in the
measurement space; providing a basis function for each base point;
and generating a weight of each basis function.
11. The method according to claim 10, wherein a constraint includes
setting a maximum and minimum temperature for each weight.
12. The method according to claim 10, wherein a constraint includes
minimizing differences in weighting of basis functions of
relatively close seat points.
13. The method according to claim 10, wherein an objective is to
minimize line fit error relative to each average temperature.
14. The method according to claim 10, further including determining
intersection points of each acoustic path, wherein each
intersection point corresponds to a base point.
15. The method according to claim 10, wherein uniformly spaced base
points are added for defining known boundary conditions.
16. The method according to claim 10, further including locating
the transceivers so as to increase acoustic path density in a
region of interest in the measurement space to thereby increase a
number of base points in the measurement space.
17. The method according to claim 10, wherein the basis function is
selected from the group consisting of Gaussian, subgaussian,
supergaussian and spline basis functions.
18. The method according to claim 10, wherein the basis function is
a combined basis function that includes more than one type of basis
function.
19. A method for optimizing base points each used in a
corresponding basis function utilized in generating a parameter map
for a hot gas flow path constrained by a boundary, comprising:
providing a plurality of transceivers, wherein each transceiver
generates an acoustic signal that travels through a measurement
space in the hot gas flow path and wherein each acoustic signal
defines an acoustic path; locating the transceivers such that the
acoustic paths travel through a region of interest in the
measurement space; determining an average temperature for each
acoustic path; determining at least one base point in the
measurement space; generating additional base points based on
apriori information; providing a basis function for each base
point; and generating a weight of each basis function.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation in part of copending
United States patent application entitled "PARAMETER DISTRIBUTION
MAPPING IN A GAS TURBINE ENGINE", filed on Apr. 9, 2015, U.S.
application Ser. No. 14/682,393, which is incorporated herein by
reference in its entirety and to which this application claims the
benefit of priority. This application claims the benefit under 35
U.S.C. .sctn. 119(e) of U.S. Provisional Patent Application No.
61/983,044 entitled "TEMPERATURE DISTRIBUTION MAPPING IN A GAS
TURBINE COMBUSTOR", filed on Apr. 23, 2014, which is incorporated
herein by reference in its entirety and to which this application
claims the benefit of priority.
[0003] This application incorporates by reference the following
co-pending United States utility patent applications in their
entirety as if fully set forth herein:
[0004] "Nonintrusive Performance Measurement of a Gas Turbine
Engine in Real Time", filed on Jul. 28, 2014, Ser. No.
14/341,950;
[0005] "Nonintrusive Transceiver and Method for Characterizing
Temperature and Velocity Fields in a Gas Turbine Combustor", filed
on Jul. 28, 2014, Ser. No. 14/341,924;
[0006] "Active Measurement Of Gas Flow Temperature, Including In
Gas Turbine Combustors", filed on Mar. 13, 2014, Ser. No.
14/207,741;
[0007] "Active Temperature Monitoring In Gas Turbine Combustors",
filed on Dec. 18, 2013, Ser. No. 14/132,001;
[0008] "Multi-Functional Sensor System For Gas Turbine Combustion
Monitoring And Control" filed on Dec. 18, 2013, Ser. No.
14/109,992;
[0009] "Temperature Measurement In A Gas Turbine Engine Combustor",
filed on Mar. 14, 2013, Ser. No. 13/804,132; and
[0010] "Gas Turbine Engine Control Using Acoustic Pyrometry", filed
on Dec. 14, 2010, Ser. No. 12/967,148, Publication No.
US2012/0150413.
[0011] This application also incorporates by reference in its
entirety as if fully set forth herein U.S. Pat. No. 7,853,433,
"Combustion Anomaly Detection Via Wavelet Analysis Of Dynamic
Sensor Signals", issued Dec. 14, 2010.
BACKGROUND OF THE INVENTION
1. Field of the Invention
[0012] The invention relates to the mapping of a parameter in
two-dimensional space and to active measurement of gas flow
parameters, such as gas flow temperature or velocity, in flow
regions of gas turbine engines. Such engines include, by way of
example, industrial gas turbine (IGT) engines, other types of
stationary gas turbine, marine, aero and other vehicular gas
turbine engines. More particularly, embodiments disclosed herein
disclose a method for optimizing base points used in parameter
mapping of a turbine hot gas flow path by determining base points
in a measurement space that are then used in basis functions for
parameter mapping.
2. Description of the Prior Art
[0013] Combustion turbines, such as gas turbine engines for any end
use application, generally comprise a compressor section, a
combustor section, a turbine section and an exhaust section. In
operation, the compressor section inducts and compresses ambient
air. The combustor section generally may include a plurality of
combustors for receiving the compressed air and mixing it with fuel
to form a fuel/air mixture. The fuel/air mixture is combusted by
each of the combustors to form a hot working gas that may be routed
to the turbine section where it is expanded through alternating
rows of stationary airfoils and rotating airfoils and used to
generate power that can drive a rotor. The expanding gas exiting
the turbine section can be exhausted from the engine via the
exhaust section.
[0014] Combustion anomalies, such as flame flashback, have been
known to occur in combustion sections of gas turbine engines. Flame
flashback is a localized phenomenon that may be caused when a
turbulent burning velocity of the air and fuel mixture exceeds an
axial flow velocity in the combustor assembly, thus causing a flame
to anchor onto one or more components in/around the combustor
assembly, such as a liner disposed around the combustion chamber.
The anchored flame may burn through the components if a flashback
condition remains for extended periods of time without correction
thereof. Thus, flame flashback and/or other combustion anomalies
may cause undesirable damage and possibly even destruction of
combustion engine components, such that repair or replacement of
such components may become necessary.
[0015] The fuel/air mixture at the individual combustors is
controlled during operation of the engine to maintain one or more
operating characteristics within a predetermined range, such as,
for example, to maintain a desired efficiency and/or power output,
control pollutant levels, prevent pressure oscillations and prevent
flameouts. In a known type of control arrangement, a bulk turbine
exhaust temperature may also be monitored as a parameter that may
be used to monitor the operating condition of the engine. For
example, a controller may monitor a measured turbine exhaust
temperature, and a measured change in temperature at the exhaust
may result in the controller changing an operating condition of the
engine. In other known types of control arrangements discrete
pitot-static or multi hole pressure probes are utilized to
determine gas flow velocity at specific locations, but grid arrays
of such probes disrupt gas flow and introduce measurement errors.
Due to such gas flow disruptions, grid arrays, when employed, have
limited numbers of widely spaced probes, which provide relatively
coarse gas flow velocity distribution and profile information.
[0016] At present, there are several different types of sensors and
sensing systems that are being used in the industry for monitoring
combustion and maintaining stability of the combustion process for
engine protection. For example, dynamic pressure sensors are being
used for combustion stability and resonance control. Passive visual
(optical visible light and/or infrared spectrum) sensors, ion
sensors and Geiger Mueller detectors are used to detect flame
on/off in the combustor, while thermocouples are being used for
flashback detection. With respect to known combustion gas flow
velocity (u) monitoring methods, pitot-static and multi hole
pressure probes utilize differential pressure techniques, hot wire
probes utilize thermal anemometry techniques, while Laser Doppler
and Particle Image Velocimetry systems utilize optical techniques
to characterize gas flow velocities. Differential pressure and
thermal anemometry instruments are intrusive point measurement
devices that disturb local gas flow around the instruments. Laser
Doppler and Particle Image Velocimetry instruments respectively
provide non-intrusive point and 2- or 3-dimensional non-intrusive
gas flow velocity measurement although they both require particle
seeding of the flow. In addition, sophisticated laser based
measurements such as Filtered Rayleigh Scattering (FRS) and other
such laser spectroscopy based techniques have been deployed to
measure gas velocity. However, these techniques are more complex
than intrusive differential pressure or thermal anemometry
instruments and require more specialized training to implement in
monitoring systems. Moreover, most optical techniques for velocity
are geared towards laboratory environments rather than in operative
engines at power plant field sites. With respect to temperature (T)
monitoring techniques, known Raman Spectroscopy, Laser Induced
Fluorescence (for both u and T monitoring), and Coherent
Anti-Stokes Raman Spectroscopy (CARS) (for both u and T monitoring)
instrumentation systems are also intended for laboratory
environments, rather than for field use in fossil power generation
equipment. Tunable Diode Laser Absorption Spectroscopy (TDLAS)
instrumentation is used in some industrial power generation field
applications, such as for temperature measurement in boilers but
that instrumentation is extremely costly: approximately US $500,000
per system. Other types of temperature measurement and combustion
anomaly detection systems have had greater acceptance in power
generation industry field applications.
[0017] Particularly, U.S. Pat. No. 7,853,433 detects and classifies
combustion anomalies by sampling and subsequent wavelet analysis of
combustor thermoacoustic oscillations representative of combustion
conditions with sensors, such as dynamic pressure sensors,
accelerometers, high temperature microphones, optical sensors
and/or ionic sensors. United States Publication No. US2012/0150413
utilizes acoustic pyrometry in an IGT exhaust system to determine
upstream bulk temperature within one or more of the engine's
combustors. Acoustic signals are transmitted from acoustic
transmitters and are received by a plurality of acoustic receivers.
Each acoustic signal defines a distinct line-of-sound path between
a corresponding transmitter and receiver pair. Transmitted signal
time-of-flight is determined and processed to determine a path
temperature. Multiple path temperatures can be combined and
processed to determine bulk temperature at the measurement site.
The determined path or bulk temperature or both can be utilized to
correlate upstream temperature in the combustor. Co-pending U.S.
utility patent application Ser. No. 13/804,132 calculates bulk
temperature within a combustor, using a so-called dominant mode
approach, by identifying an acoustic frequency at a first location
in the engine upstream from the turbine (such as in the combustor)
and using the frequency for determining a first bulk temperature
value that is directly proportional to the acoustic frequency and a
calculated constant value. A calibration second temperature of the
working gas is determined in a second location in the engine, such
as the engine exhaust. A back calculation is performed with the
calibration second temperature to determine a temperature value for
the working gas at the first location. The first temperature value
is compared to the back calculated temperature value to change the
calculated constant value to a recalculated constant value.
Subsequent first temperature values at the combustor may be
determined based on the recalculated constant value.
[0018] A need exists for techniques for creating real time,
two-dimensional maps of temperature distribution in a flow region
of a gas turbine engine wherein base points used in temperature
mapping of a turbine hot gas flow path are optimized by determining
acoustic signal intersection points and designating the
intersection points as base points that are then used in basis
functions for temperature mapping.
[0019] A further need exists in the art for an integrated gas
turbine engine monitoring and control system for measuring gas flow
velocity, temperature and detecting a broad range of possible
combustor failures or, more satisfactorily, precursors to faults,
during combustion, sharing common sensors and, if desired, a common
controller.
[0020] Another need exists in the art for a gas turbine engine
active velocity and temperature monitoring system that maps actual
combustor velocity and temperature in real time without the need to
obtain reference temperatures from other locations within the
engine, such as known bulk temperature systems that back calculate
combustor temperature based on temperature measurements obtained in
the engine exhaust system.
[0021] An additional need exists for an active gas flow velocity
and temperature monitoring system that shares sensors commonly used
with combustion turbine monitoring and control systems, so that
active velocity and temperature monitoring can be integrated within
the monitoring and control system.
[0022] A further need exists for a technique for providing
real-time temperature information in a plane transverse to a gas
flow in a turbine engine for controlling the engine.
[0023] Another need exists for a technique for controlling a gas
turbine combustor based on average temperature measurements along
lines in a plane transverse to the combustor flow.
SUMMARY OF THE INVENTION
[0024] In an embodiment, a method is disclosed for optimizing a
number of base points each used in a corresponding basis function
utilized in generating a parameter map for a hot gas flow path
constrained by a boundary. The method includes providing a
plurality of transceivers, wherein each transceiver generates an
acoustic signal that travels through a measurement space in the hot
gas flow path and wherein each acoustic signal defines an acoustic
path. The method also includes locating the transceivers such that
the acoustic paths travel through a region of interest in the
measurement space. In addition, an average temperature for each
acoustic path is determined. Next, at least one base point in the
measurement space is determined. The method includes providing a
basis function for each base point and generating a weight of each
basis function. Further, the location of the transceivers
corresponds to a shape of the measurement space and the region of
interest may include at least one hot section or at least one cold
section.
[0025] In another embodiment, a method is disclosed for optimizing
a number of base points each used in a corresponding basis function
utilized in generating a parameter map for a hot gas flow path
constrained by a boundary. In the method, a plurality of
transceivers is provided, wherein each transceiver generates an
acoustic signal that travels through a measurement space in the hot
gas flow path and wherein each acoustic signal defines an acoustic
path. The method also includes locating the transceivers such that
the acoustic paths travel through a region of interest in the
measurement space. In addition, an average temperature for each
acoustic path is determined. Next, intersection points of each
acoustic path are determined, wherein each intersection point
corresponds to a base point. The method also includes generating
additional base points based on apriori information. Further, the
method includes providing a basis function for each base point and
generating a weight of each basis function.
[0026] The respective objects and features of the present invention
may be applied jointly or severally in any combination or
sub-combination by those skilled in the art.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] The teachings of the present invention can be readily
understood by considering the following detailed description in
conjunction with the accompanying drawings, in which:
[0028] FIG. 1 is a perspective cross-sectional view of a gas
turbine engine illustrating implementation of a system for
determining combustor gas flow active velocity and temperature
measurement, in accordance with embodiments of the invention;
[0029] FIG. 2 is a cross-sectional view of a gas turbine combustor
incorporating an embodiment of a monitoring system for determining
combustor gas flow active velocity and temperature measurement, in
accordance with embodiments of the invention;
[0030] FIG. 3 is a cross-sectional view of the system of FIG. 2,
taken along 3-3 thereof, in accordance with aspects of the
invention;
[0031] FIG. 4 is a block diagram of an embodiment of a controller
for implementing embodiments of the present invention in the
monitoring system for determining combustor gas flow active
velocity and temperature measurement, in accordance with
embodiments of the invention;
[0032] FIG. 5 is a schematic perspective view of exemplary sonic
sensor arrays used by the gas flow monitoring system to measure gas
flow velocity in a gas turbine combustor, in accordance with
embodiments of the invention;
[0033] FIG. 6 is an exemplary schematic representation of gas flow
velocity in the turbine combustor of FIG. 5 in the line-of-sight
between acoustic sensors 32B and 34C;
[0034] FIG. 7. is a cross-sectional slice A of the gas flow
velocity of FIG. 6 taken along 7-7 thereof, which corresponds to
the line-of-sight between acoustic sensors 32B and 34C;
[0035] FIG. 8 is a composite gas flow velocity profile of the
respective velocities measured by the gas flow velocity monitoring
system, in accordance with embodiments of the invention;
[0036] FIG. 9 is a schematic perspective view of exemplary sonic
sensor arrays used to measure gas flow temperature in a gas turbine
combustor, in accordance with embodiments of the invention;
[0037] FIG. 10 is a flow chart illustrating implementation of an
embodiment of the methods for measuring gas flow velocity and
temperature active measurement in a gas turbine combustor, in
accordance with embodiments of the invention; and
[0038] FIG. 11 is a flow chart illustrating implementation of an
embodiment of the method for measuring active gas flow velocity, in
accordance with embodiments of the invention.
[0039] FIG. 12 is a schematic illustration of a gas turbine engine
showing sensor installations in several alternative regions, in
accordance with embodiments of the invention.
[0040] FIG. 13 is a schematic illustration of a system for mapping
flow parameters in a gas turbine engine region, in accordance with
embodiments of the invention.
[0041] FIG. 14A is a schematic depiction of a bilinear
representation of a parameter along a path, in accordance with
embodiments of the invention. FIG. 14B is a schematic
representation of a two-dimensional space with two bilinear
representations of path profiles, in accordance with embodiments of
the invention.
[0042] FIG. 15 is a flow chart showing a technique for mapping a
parameter based on average path values, according to embodiments of
the invention.
[0043] FIG. 16 is a diagram showing parameter profiles for a single
path, according to embodiments of the invention.
[0044] FIG. 17 is a flow chart showing a technique for mapping a
parameter based on average path values, according to embodiments of
the invention.
[0045] FIG. 18 is a schematic view of a two dimensional space
showing measurement paths and a grid segment, according to
embodiments of the invention.
[0046] FIG. 19 is a flow chart showing a technique for mapping a
parameter based on average path values, according to embodiments of
the invention.
[0047] FIG. 20 is an exemplary cross sectional view of a plurality
of acoustic paths or lines located in a measurement space of a hot
gas flow path.
[0048] FIG. 21 depicts random base points used for generating a
temperature map, wherein the base points are seat points for a
basis function.
[0049] FIG. 22 depicts base points that coincide with acoustic path
intersection points in accordance with the invention, wherein the
base points are seat points for a basis function.
[0050] FIG. 23 depicts transducers that are arranged to increase a
number of intersections in a desired region of interest for
temperature mapping.
[0051] FIG. 24 is a view of an exemplary temperature map wherein
the map is generated without a constraint that minimizes
differences in weighting functions.
[0052] FIG. 25 is a view of an exemplary temperature map wherein
the constraint for minimizing differences in weighting functions is
utilized.
[0053] FIG. 26 is a flowchart depicting a method for optimizing a
number of base points used in temperature mapping in accordance
with the invention.
[0054] To facilitate understanding, identical reference numerals
have been used, where possible, to designate identical elements
that are common to the figures.
DETAILED DESCRIPTION
[0055] After considering the following description, those skilled
in the art will clearly realize that the teachings of the invention
can be readily utilized for active acoustic velocity and
pyrometry-based gas flow velocity and temperature measurement.
Embodiments of the invention are used for monitoring of gas turbine
combustors, including industrial gas turbine (IGT) combustors by
incorporating them into the combustion monitoring and control
system by addition of an acoustic transmitter or acoustic
transceiver that transmits sound waves through gas flow in a
line-of-sight with a plurality of acoustic sensors, such as dynamic
pressure sensors. For velocity measurement, sound transmission
time-of-flight that is directed generally transversely through the
gas flow path is measured by the controller and correlated with gas
flow velocity along the line-of-sight. The gas flow velocity
determination includes compensation for impact of the
thermodynamically interrelated temperature, gas constant and speed
of sound influences on the first time-of-flight, in order to
determine absolute gas flow velocity.
[0056] In an integrated acoustic pressure-based sensor and
monitoring/control system embodiment, the controller correlates
velocity and, if desired, absolute active path temperatures
simultaneously with acoustic transmission and time-of-flight
analysis techniques. Where velocity and temperature are measured
simultaneously the absolute active path temperature is utilized to
compensate for the aforementioned thermodynamic influences on gas
flow absolute velocity. Alternatively in other embodiments the
speed of sound influence on the first time-of-flight is utilized to
determine absolute gas flow velocity rather than absolute active
path temperature. In such embodiments, compensation for the speed
of sound in the velocity monitoring is accomplished by substituting
for the first transmitters a set of first transceiver/transducers
that are capable of transmitting and receiving acoustic signals,
and generating output signals and substituting for the first
sensors a set of second transducers that are capable of
transmitting and receiving acoustic signals and generating output
signals. Acoustic signals are transmitted and received from the
first to the second transducers and time-of-flight is determined. A
reverse acoustic signal is transmitted from the second to the first
transducers and the reverse time-of-flight is determined. The
respective first and first reversed acoustic signals
times-of-flight are used to determine the speed of sound c. The
determined speed of sound c is then utilized for determination of
the actual gas flow velocity.
[0057] In embodiments of the invention active velocity or active
velocity/temperature measurements are used as monitoring parameters
for gas flow in a combustion monitoring and control system that can
identify and classify gas flow anomalies (e.g., combustion
anomalies), for example by using wavelet or Fourier analysis
techniques. Some embodiments of the methods and system incorporate
one or more acoustic dynamic pressure transceiver/transducer
combination transmitter/sensors that are selectively oriented or
arrayed in sequential axial planar positions within the combustor.
Known transceiver/transducer component designs and their related
controller components have been used reliably and cost effectively
in the past in power generation field service. By reconfiguring
those types of known components into the gas flow control and
monitoring systems of the present invention combustion turbine and
other combustion power generation equipment can be monitored and
controlled with simpler instrumentation hardware configurations
that provide detailed active gas flow velocity and temperature
distribution information useful for precise combustion control.
Monitoring and Control System Structure
[0058] Referring to FIGS. 1 and 2 an exemplary industrial gas
turbine engine 10 is shown. The exemplary engine 10 includes a
compressor section 12, a combustor section 14, a turbine section
16, and an exhaust section or system 18. The combustor section 14
includes a plurality of combustors 20. Each combustor 20 has a
combustion shell 22 and a cover plate 24. The combustor liner or
basket 26 and transition duct 27 define a passage for conveying hot
working gas that flows in the direction F to the turbine section
16. The system of the present invention is operable with known
combustor geometry gas turbine engine designs, including can,
can-annular or annular construction combustors in stationary
land-based or vehicular applications.
[0059] During operation of the engine 10, compressed air from the
compressor section 12 is provided to the combustor section 14 where
it is combined with fuel supplied by fuel injection system 28 in
the combustors 14. The fuel/air mixture is ignited to form
combustion products comprising the hot working gas. It may be
understood that combustion of the fuel and air may occur at various
axial locations along the passage through the combustor liner or
basket 26 and the transition duct 27 to the inlet of the turbine
section 16. The hot working gas is expanded through the turbine
section 16 and is exhausted through the exhaust section/system
18.
[0060] Referring to FIGS. 1 and 2, in accordance with an aspect of
the invention, a combustion monitoring and control system 29 is
provided, which can identify and classify combustion anomalies and
actively control the gas turbine combustion process within one or
more of the engine 10 combustors 20. In this regard, the engine 10
may include may comprise one or more of the monitoring and control
system(s) 29: e.g., one system 29 for each combustor 20, or a
single system 29 may service each combustor 14 of the engine 10.
Similarly, clusters of combustors 20 may be served by one system
29, with other cluster(s) being served by other systems. Thus the
consolidated monitoring system for an engine 10 can determine
deviations between respective combustors and compare their relative
performance no matter what engine combustor structure or
orientation is employed by the engine design: whether a stationary,
land-based turbine engine or a vehicular engine for aero, marine or
land vehicular applications.
[0061] As shown in FIGS. 2, 3, 5 and 9 the system 29 includes an
array of a plurality of known acoustic transceiver/transducers
32A-H and 34A-H that are capable of transmitting and receiving
acoustic oscillation waves along exemplary the line-of-sight paths
shown in dashed lines in FIGS. 5 and 9. The transceiver/transducer
arrays 32, 34 are capable of generating respective sensor output
signals indicative of combustion thermoacoustic oscillations in
each respective monitored and controlled combustor 20. Other system
embodiments can be constructed with at least two, but preferably
more acoustic sensors, whether functionally part of a transceiver
component or as a stand-alone component. Acoustic frequencies and
amplitudes sensed by those acoustic sensor portions of the
transceivers are generated as a result of combustion events in the
working combustion gas, defining acoustic sources that occur within
the combustor 20 hot gas path. The monitoring and control system 29
is configured to transform the sensed thermoacoustic oscillation
information into a form that enables the occurrence of combustion
anomalies of interest to be discerned. As such, flame flashback
events and other types of combustion anomalies of interest may be
detected and extracted from sensed thermoacoustic oscillations in
the combustor 14 that are monitored by the
transceiver/transducer/sensors positioned in and/or around the
combustor 14. Depending upon the system 29 configurations and
application, the acoustic sensors comprise any combination of one
or more of a dynamic pressure sensor, a microphone, an optical
sensor or an ionic turbine inlet sensor. Pressure sensors sense the
amplitudes of thermoacoustic oscillations in the combustor 20 as
well as pulsation frequencies. A high temperature microphone may be
utilized to measure acoustic fluctuations in the combustor 14. An
optical sensor may be utilized to measure a dynamic optical signal
within the combustor 20. An ionic sensor may be utilized to measure
dynamic ionic activity within the combustor 20.
[0062] An exemplary acoustic sensor array shown schematically in
FIGS. 2, 3, 5 and 9 comprises transceiver/transducers 32A-H and
34A-H that function as at least one acoustic transmitter that
transmits in turn to at least one and preferably a plurality of the
dynamic pressure sensors in the array. The transceiver/transducers
32, 34 are arrayed axially and radially within the combustor 20 by
known mounting structures and methods, such as J tubes or rakes,
within the combustor shell 22 proximal the combustor basket or
liner 26, and/or proximal the transition 27 junction with the
turbine section 16. In FIG. 3 the sensors are
radially/circumferentially arrayed transceivers 34A-34H that are
capable of transmitting and receiving acoustic oscillation waves
along the line-of-sight paths similar to the transceivers 32A-H
shown in dashed lines in FIG. 9. Other types of known sensors, such
as individual thermocouple temperature sensors or thermocouple
arrays may be employed within the gas turbine engine. For example
in FIG. 3 thermocouple 36 measures combustion temperature in the
combustor 20. While exemplary three-dimensional annular combustion
flow paths and axially spaced, two-dimensional circular-annular
transceiver/transducer arrays are shown in the figures, other
combustion flow path and array orientations may be utilized, in
practicing embodiments of the invention, including square- or
rectangular-shaped geometries.
[0063] As shown in greater detail in FIGS. 3 and 4, the monitoring
and control system 29 comprises a known controller 40, coupled to
the transceiver/transducers 32, 34, that is capable of correlating
sensor output signals with gas flow velocity and combustion
temperature in a monitoring section 42 and conducting combustion
dynamics analysis of the combustion process in an analysis section
44. The monitoring section 42 and dynamic analysis 44 section
outputs are utilized by the gas turbine control system 46 that can
send control signals to other gas turbine controls subsystems,
including industrial gas turbine (IGT) controls subsystems, such as
the fuel injection system 28, in order to unload or shut down the
engine 10 in response to changes in monitored combustion conditions
within the combustor 20.
[0064] Referring to the exemplary controller 40 embodiment shown in
FIG. 4, it includes one or more processors 50, system memory 52 and
input/output control devices 54 for interfacing with the associated
engine 10 controls, such as the fuel injection control system 28,
and the acoustic transceiver/transducer 32, 34 acoustic
transmitters and sensors 32 (or functionally equivalent performing
separate discrete transmitters and receiver sensors), networks,
other computing devices, human machine interfaces for
operator/users, etc. The controller 40 may also include one or more
analog to digital converters 56A and/or other components necessary
to allow the controller 40 to interface with the transceivers 32,
34 and/or other system components to receive analog sensor
information. Alternatively, and/or additionally, the system 29 may
include one or more analog to digital converters 56B that interface
between the transceivers 32, 34 (or functionally equivalent
performing separate discrete transmitters and receiver sensors) and
the controller 40. As yet a further example, certain transceivers
32, 34 may have an analog to digital converter 56C integral
therewith, or are otherwise able to communicate digital
representations of sensed information directly to the controller
40.
[0065] The processor(s) 50 may include one or more processing
devices such as a general purpose computer, microcomputer or
microcontroller. The processors 50 may also comprise one or more
processing devices such as a central processing unit, dedicated
digital signal processor (DSP), programmable and/or reprogrammable
technology and/or specialized component, such as application
specific integrated circuit (ASIC), programmable gate array (e.g.,
PGA, FPGA).
[0066] The memory 52 may include areas for storing computer program
code executable by the processor(s) 50, and areas for storing data
utilized for processing, e.g., memory areas for computing wavelet
transforms, Fourier transforms or other executed mathematical
operations used to operate the monitoring and control system 29, as
described more fully herein below. As such, various aspects of the
present invention may be implemented as a computer program product
having code configured to perform the detection of combustion
engine anomalies of interest, combustion dynamics and engine
control functions as set out in greater detail herein.
[0067] In this regard, the processor(s) 50 and/or memory 52 are
programmed with sufficient code, variables, configuration files,
etc., to enable the controller 40 to perform its designated
monitoring and control functions. For example, the controller 40
may be operatively configured to sense thermoacoustic conditions,
analyze thermoacoustic conditions based upon inputs from one or
more transceiver/transducers 32, 34, control features of the engine
10 in response to its analysis, and/or report results of its
analysis to operators, users, other computer processes, etc. as set
out in greater detail herein. Thus, all of the dynamic output
signals originating from transceiver/transducers 32, 34 may be
communicated to a single processor 50. In this implementation, the
single processor 50 will process the sensor dynamic output signals
using the data analysis and control functions described in greater
detail herein, such that it appears as if the results are computed
in a generally parallel fashion. Alternatively, more processors 50
can be used and each processor may be utilized to process one or
more transceiver/transducers 32, 34 dynamic signals, e.g.,
depending for example, upon the computation power of each
processor.
Monitoring and Control System Operation
[0068] The concepts of acoustic temperature and velocity
measurements are both based on creating a sonic wave, listening to
it across the gas stream and finding an average speed of sound
across a given path, which is then descriptive for the gas velocity
or velocity/temperature. FIGS. 10 and 11 are flow charts
illustrating graphically exemplary operation of a monitoring and
control system 29 embodiment of the invention that actively
monitors and measures both gas flow velocity and temperature using
acoustic measurement methodologies. The thick solid and dotted line
operational blocks relate to previously described combustion
dynamics analysis 42 (solid block), temperature monitoring and
determination 44 and gas turbine control 46 functions (including by
way of example IGT control functions) that are performed within the
controller 40. In step 100 sensor signals generated by the sensor
components within the transceiver/transducers 32A-H, 34 A-H are
read. In step 110 amplitudes of one or more of the sensor signals
are compared to previously established alarm limits. For example in
IGT applications the step 120 low frequency dynamics (LFD) below
100 Hz are of importance because of potential resonance influence
at the 50 Hz or 60 Hz engine rotational speed. Other frequency
bands of interest are intermediate frequency dynamics (IFD) between
approximately 100-500 Hz and high frequency dynamics (HFD) above
500 Hz. If an alarm limit is exceeded the controller 40 sends a
control command, for example to the fuel injection system 28, to
unload or shut down the engine 10 in step 400.
[0069] If an alarm limit is not exceeded in step 110, then
frequency analysis for dynamics is performed in anomaly detection
portion of the combustion dynamics analysis sub system. An
exemplary description of how to perform anomaly detection is in
U.S. Pat. No. 7,853,433 that is incorporated herein by reference.
The sampled high speed dynamic pressure signal is obtained from the
sensors in step 130 and time divided into segments in step 140. In
step 150 the time-frequency divided sample segments are analyzed
using the wavelet analysis technique described in U.S. Pat. No.
7,853,433. Alternatively, a known Fourier spectral analysis that
converts the time segments into frequency space, analyzes dominant
frequencies by identifying the peak frequencies and their
respective amplitudes, and identifies amplitudes exceeding defined
thresholds. If it is determined that a combustion anomaly or
anomalies have occurred in step 160 the combustor temperature as
determined in the temperature monitoring and determination
subsystem 44 is compared with the anomaly information obtained by
the Fourier or wavelet analysis techniques, or both. In step 180
the anomaly classification as a flame on, flame out or flashback is
made in conjunction with the passive or path temperature
information obtained from the temperature monitoring and
determination subsystem 44. For example in a gas turbine flameout
the combustor temperature drops off dramatically. Conversely in a
flashback scenario the combustor temperature rises dramatically
upstream within the combustor 14. When the anomaly determination is
made in step 180 appropriate control signals to unload or shut down
the engine are made in the engine control system 46.
[0070] The temperature monitoring and determination subsystem 44
may comprise passive temperature determination utilizing the
passive acoustic method described in United States patent
application "Temperature Measurement in a Gas Turbine Engine
Combustor:, filed on Mar. 14, 2013, Ser. No. 13/804,132,
incorporated by reference herein, and/or real time actual path
temperature determination within the combustor 14. Real time actual
path temperature is determined by adaptation of the 2-D planar
acoustic pyrometry technique for gas turbine exhaust system
temperature determination described in United States Patent
Publication No. US2012/0150413 (also incorporated by reference
herein) or by a 3-D technique that determines one or more path
temperatures between the sensor arrays 32/34 of FIG. 5, that is
further described in greater detail herein.
[0071] In the passive temperature determination method, sampled
high speed dynamic pressure signals from the
transceiver/transducers 32/34, such as obtained in step 130 are
analyzed for dominant modes in step 200. Combustor temperature is
calculated based on frequency using the passive acoustic method in
step 210. The passive value is calibrated with a reference
temperature value in step 220 in order to obtain an active
temperature value within the combustor 14. The calibrated passive
temperature value determined in step 220 is utilized in step 230 to
determine the bulk mean temperature of the combustion gas in step
230. The reference temperature value used in step 220 may be
obtained from one or more thermocouples 36 in the combustor or
thermocouples located in the exhaust system 18 (not shown). The
reference temperature value may be an actual path temperature
measured in the exhaust system 18, as described in United States
Patent Publication No. US2012/0150413 or a real time path
temperature measured in the combustor 14 that is determined in
steps 300-330.
[0072] The 2-D real time path temperature is measured by
transmitting one or more acoustic signals in an acoustic
transceiver/transducer 32, 34 or other discrete transmitter, such
as in the 2-D planar pattern shown for the
(n=8+transceiver/transducers 32A-H in FIG. 9. For example,
transceiver/transducer 32A transmits a signal that is received by
the remaining (n-1) transceiver/transducers 32B-H and the
time-of-flight for each line-of-sight path is determined. However,
at least one, preferably two or more sensor elements in the
remaining transceiver/transducers 32B-H receive the acoustic
signal(s) in step 310. Preferably in practice several
transceiver/transducers (transmit and receive acoustic signals)
circling one plane such that the paths between all transceivers
form a grid with desired coarseness which results in the spatial
resolution of the temperature measurement. For example, for a
cylindrical combustor the transceivers could be equally spaced
around the periphery as shown in FIGS. 3 and 9. These could be
either fired sequentially (one at a time) or simultaneously with
disjoint sound patterns that can be readily differentiated. For
sequential firing one transceiver is creating sounds while all
remaining transceivers record it to estimate the travel time for
the respective paths. Each of these line-of-sight paths represents
an average temperature along that path. The average temperatures
over different paths are combined to a two-dimensional map shown in
FIG. 9, using a known computer tomography technique.
[0073] The 2-D time-of-flight sound data are converted to gas
temperature using active acoustics in step 320, such as by
utilization of the methods described in the aforementioned United
States Patent Publication No. US2012/0150413 that is incorporated
by reference herein. The real time path temperature that is
determined in step 330 is the localized active temperature value
along the line-of-sight transmission path. A plurality of active
temperature values measured along different acoustic paths by
performing the steps 300-330 can be utilized to determine the
combustor 14 bulk temperatures, alone or in parallel with the
dominant frequency passive acoustic method of steps 200-230. While
a single path active temperature measurement between a single
transmitter 30 and acoustic sensor 32 provides useful control
information, arraying a plurality of transceiver/transducers 32, 34
selectively in any axial, circumferential and/or radial pattern or
combinations thereof within a combustor 14 (see, e.g., FIG. 2, 3,
5, or 9) or in a series of combustors 14 facilitates active real
time two- or three-dimensional combustion temperature monitoring
within the gas turbine engine 10.
[0074] The 2-D or 3-D real time path temperature determined in
steps 300-330 can be utilized as an input for other monitoring and
control functions, with or without one or more of the combustion
dynamics analysis 42, passive temperature monitoring and
determination 44 and control 46 functions described in the
exemplary integrated monitoring and control system 29 described
herein. For example combustor turbine inlet temperature (TIT) can
be actively monitored in real time and used as a control parameter
for the combustion process. The combustion active path temperature
determined in steps 300-330 can be utilized to control the fuel/air
mixture in the combustor 14 via the fuel injection system 28. The
real time path active temperature can be utilized as an input for
active actual gas flow velocity measurement in an industrial gas
turbine combustor or in other types of gas flow environments.
[0075] Embodiments of the present invention measure 3-D gas flow
velocity and/or gas flow temperature by correlation with sonic
time-of-flight along a line-of-sight sonic pathway between axially
spaced, transversely oriented sonic transmitter and sensor (or
transceiver/transducers incorporating the sensors and
transmitters), so that the line-of-sight along the pathway is
oriented transverse, as opposed to parallel to the gas flow path.
In order to determine gas flow absolute velocity, the
time-of-flight data are corrected or compensated for thermodynamic
influences on gas temperature, gas constant and speed of sound. As
noted above gas temperature along a line of sight can be determined
using the real time active path temperature or temperature
independently obtained from another measurement device (e.g.,
thermocouple 36). Alternatively localized speed of sound c can be
determined by measuring bi-directional time-of-flight (i.e.,
forward/downstream transmission and reverse/upstream transmission).
The aforementioned thermodynamic influences are governed by the
known equation:
c(x,y,z)=(.gamma.RT).sup.1/2
Where:
[0076] c(x,y,z) is the isentropic speed of sound; .gamma. is
specific heat ratio; R is the gas constant; and T is the gas
temperature. Therefore, once the speed of sound along a path is
known, the average path temperature and absolute velocity can be
determined utilizing embodiments of the invention further described
herein.
[0077] For accurate absolute velocity or temperature measurement,
two planes of transceiver/transducers 32, 34 are oriented in
axially spaced, opposed relationship within the gas flow, as shown
in FIG. 5. The two transceiver/transducer planes 32, 34 are
preferably apart by approximately the same order of magnitude as
the diameter (circular) or width (square or rectangular) of the
monitored gas flow geometry. That is, the axial distance between
the two planes should be determined according to the geometry and
scale of the interrogated environment as well as the anticipated or
possible ranges of gas flow gas constant, temperature and
velocity.
[0078] For gas flow velocity estimation, the gas flow is measured
axially and transverse to the flow direction. For example, when
transceiver/transducer 32A in plane Z.sub.I fires or transmits a
signal, all transceiver/transducers 34B-H in plane Z.sub.II that
are not parallel-aligned with the signal firing sensor will be
listening, thereby creating several paths across the gas flow (n-1
paths for n sensors). The signal transmitting/receiving firing
process continues sequentially with the second
transceiver/transducer 32B on plane Z.sub.I firing to the remaining
(n-1) transceiver/transducers 34A and 34C-H, which receive that
transmitted signal. The transmitted signal firing will continue on
with the consecutive transceivers firing and creating n-1 paths for
each firing. In the embodiment of FIG. 5, having 8
transceivers/transducers in each of the two axially spaced arrays
there are a total of 64 paths in three dimensions. In addition, to
alleviate the directional ambiguity of the velocity (to identify
reverse flows and perhaps turbulence fluctuations in reverse
direction) the same process will be repeated with
transducer/transceivers 34 in plane Z.sub.II firing and
transceiver/transducers in plane Z.sub.I receiving the reverse
direction transmitted acoustic signal, assuming that the gas flow
temperature is already known. Instead of transmitting/firing
acoustic signals sequentially from each transceiver/transducer, a
sound pattern with a slightly different acoustic signature can be
transmitted from each respective transceiver/transducer 32A-H,
34A-H simultaneously, which shortens measurement time Referring to
steps 500 and 510 of the gas flow velocity measurement method flow
chart of FIG. 11, once all transceiver/transducers in planes
Z.sub.I and Z.sub.II have fired and the transmitted acoustic
signals have been received by the opposing plane of transversely
aligned transceivers/transducers, the process preferably repeats
continually in real time while a 3-D velocity map u is constructed
from the spatially distributed line-of-sight acoustic paths, using
known 3-D tomographic mapping techniques, such as those utilized in
medical or industrial computed tomography systems. The velocity
information is extracted and mapped, as shown in FIG. 8. Similarly,
a 3-D temperature map T can be constructed utilizing the time of
flight data, as will be described in greater detail herein,
[0079] After all of the transceiver/transducers 32, 34 in a planar
array have fired acoustic signals the respective line-of-sight flow
path time-of-flight data are used to derive absolute velocity in
the gas flow path in step 560, once corrected for the thermodynamic
effects of temperature, gas constant and the speed of sound, as
described in greater detail below. Flow velocity measurement
accuracy potentially decreases as flow velocity approaches the
speed of sound, assuming constant gas temperature in the velocity
measurements. Flow velocity below a Mach number of approximately
0.5 is not believed to impact velocity measurement significantly.
Therefore it is preferable, but not required, that measured flow
velocities should be smaller than half of the local speed of sound
that is measured. This method can accurately measure high
temperature gas flows, including turbine engine gas flows, despite
relatively high absolute velocities, because the local speed of
sound increases with temperature.
[0080] Once acoustic time-of-flight data are available, they are
used by the monitoring and control system 29 or other remote
monitoring system to determine velocity along their respective
acoustic paths in accordance with the remainder of the steps of
FIG. 11. Referring to FIGS. 6 and 7, information sound propagation
is linearly affected by the gas flow. Relative gas flow velocity
for a given temperature, gas constant and speed of sound is
determined by the known equation:
t BC = .intg. B C 1 c ( x , y , z ) + p .fwdarw. BC u .fwdarw. ( x
, y , z ) ds ##EQU00001##
[0081] Where:
[0082] t.sub.BC is the time-of-flight from the first transmitter B
to the first sensor C;
[0083] c is the speed of sound in the gas flow for the temperature
and gas constant;
[0084] {right arrow over (P)}.sub.BC is the unit vector along the
first line of sound path A between B and C; and
[0085] {right arrow over (u)}(x, y, z) is velocity vector in the
gas flow.
[0086] The exemplary planar slice along the line-of-sound path A
shows a simplified flow pattern. Referring again to the flow chart
of FIG. 11, the relative gas flow velocity is corrected for
thermodynamic temperature, gas flow and speed of sound influences,
in order to derive absolute velocity in step 560. If the path
temperature is available (step 520) its influence on the speed of
sound can be corrected by known tomography methods, in order to
derive the gas flow absolute velocity along the line-of-sound path.
If the path temperature is not available, times-of-flight for
forward (steps 500, 510) and reverse (steps 530, 540) acoustic
signal transmission are acquired and used to extract the speed of
sound without effect of the gas velocity in accordance with the
following equations. The reverse time-of-flight from
transducer/transceiver C to transducer/transceiver B is determined
by the following equation, similar to that for the forward or
downstream direction set forth above:
t CB = .intg. C B 1 c ( x , y , z ) + p .fwdarw. BC u .fwdarw. ( x
, y , z ) ds ##EQU00002##
[0087] The forward and reverse times-of-flight are added in
accordance with the following equation:
t BC + t CB = .intg. B C 2 c ( x , y , z ) c ( x , y , z ) 2 - p
.fwdarw. BC u .fwdarw. ( x , y , z ) 2 ds ##EQU00003##
[0088] Given that the square of the speed of sound c is much
greater than the square of the gas flow velocity u, the equation is
reduced to:
t BC + t CB .apprxeq. .intg. B C 2 c ( x , y , z ) ds
##EQU00004##
[0089] where: [0090] t.sub.BC is the time of flight from the first
transceiver/transducer B to the second transceiver/transducer C;
[0091] t.sub.CB is the time of flight from the second
transceiver/transducer C to the first transceiver/transducer B;
[0092] c is the speed of sound in the gas flow for the temperature
and gas constant; [0093] {right arrow over (p)}.sub.BC is the unit
vector along the first line of sound path; and [0094] {right arrow
over (u)}(x, y, z) is the velocity vector in the gas flow.
[0095] The speed of sound c determined in step 550 of FIG. 11 is
then used to correct the downstream time-of-flight data for that
speed of sound in step 560. The corrected downstream time-of-flight
data are used to determine gas flow absolute velocity in step 570.
Where the path temperature T along a line-of-flight is not known,
the same speed of sound c determined in step 550 is utilized in
some embodiments of the invention to determine T, using the
previously described isentropic speed of sound relationship c(x, y,
z)=(.gamma.RT).sup.1/2, as .gamma., R and c(x, y, z) are now known.
In a similar manner to the path velocity determinations previously
described, once all the path temperatures T are known from each
receiver/transmitter unit back and forth, there will be 64
(assuming exemplary 8-sensor case) iso-temperature lines in
3-dimensions. Then using known 3-D tomographic mapping techniques,
the 3-dimensional temperature distribution is mapped.
[0096] Advantageously the active acoustic temperature and velocity
measurements are performed simultaneously in real time, thus
mapping both gas flow temperature (3-D or alternatively the 2-D
mapping of FIGS. 9) and 3-D gas flow velocity (FIG. 8). An
exemplary acoustic signal transmission and reception timing
sequence to perform simultaneous velocity and temperature
measurement is to emit an acoustic signal with a
transceiver/transducer on a first array plane (e.g., 32A at
Z.sub.I). The corresponding transversely oriented
transceivers/transducers on an axially spaced opposed second plane
34B-H at Z.sub.II) receive the signal for velocity processing
and/or temperature processing, if 3-D temperature measurement is
utilized. If only 2-D temperature measurement is utilized the
remainders of the transceiver/transducers on the first array plane
(e.g., 32B-H at ZI) receive the signal for temperature processing.
As previously noted the transmission and receiving process also can
be accelerated by utilizing unique signal transmission patterns for
each transceiver/transducer. There are tradeoffs associated with
use of 2-D or 3-D temperature measurement. Where 3-D temperature
measurement techniques are utilized, accuracy of both temperature
and velocity map may not be the most desired in case of gas
velocities of Mach 0.3 or above as the approximation shown in the
equation
t BC + t CB .apprxeq. .intg. B C 2 c ( x , y , z ) ds
##EQU00005##
may be less accurate in those velocities ranges, because there are
no independently determined temperature reference values. However,
independent temperature T reference values may be determined, using
a pair of axially separated 2-D acoustic signal sets and two
individual acoustic temperature maps determined with the respective
2-D time-of-flight signal sets. The 2-D temperature maps are in
turn interpolated to create a volumetric temperature map. This
volumetric map will be used to provide the temperature values T
utilized in the isentropic speed of sound equation, along with the
known gas constant R and specific heat ratio .gamma. to extract
speeds of sound c. The speed of sound is then used to extract the
velocity vectors u(x,y,z). Once the velocity vectors are extracted
the velocity components can be mapped, eliminating the limitation
of below Mach 0.3 gas velocities inherent in the previously
descried 3-D velocity and temperature mapping methods.
[0097] Combustor active gas flow velocity or velocity/temperature
monitoring utilizing the system and method embodiments described
herein with arrays of commonly utilized acoustic sensors is
believed to provide faster velocity and temperature change response
than known velocity and temperature monitoring systems. In
accordance with embodiments of the invention one array of commonly
utilized, reliable acoustic transceiver/transducer
sensor-transmitters or arrays of separate discrete acoustic sensors
and transmitter pairs can be placed in a combustion flow path under
field conditions and monitored to provide active, real time
simultaneous velocity and temperature data and anomaly detection
that are all useful for monitoring and control of combustion power
generation equipment, such as industrial gas turbines.
Mapping Parameter Distributions
[0098] A parameter map in a two-dimensional or three-dimensional
space has numerous uses in the design, diagnosis and control of
machinery. For example, a temperature or velocity map of a region
of the gas path is useful in diagnosing and accurately measuring
the performance of a gas turbine engine. The map may, for example,
be a temperature map in the vicinity of the combustor flame or may
be a turbine inlet temperature map in the region exiting the
combustor. Simple temperature maps are presently created using
thermocouple temperature rakes and temperature probes mounted on
the first row vane to obtain measurements from which a crude linear
temperature profile may be fit. Those short-term, intrusive
methodologies provide crude profiles based on sensor locations but
do not provide a spatially resolved map of temperatures in real
time that one could utilize to control a gas turbine or to
understand temperature distribution during a new engine design
validation process.
[0099] Presently described are techniques for using acoustic or
other signals that are transmitted and received in a region of a
gas turbine engine. Many flow regions of a gas turbine engine may
be of interest in the use of the presently described techniques,
and several exemplary regions are depicted in the schematic diagram
of the gas turbine engine 1200 shown in FIG. 12. An inlet
temperature map 1211 of a gas turbine inlet 1210 may be created
using the described techniques and using acoustic sensors 1212
arranged circumferentially around a planar region of the inlet. A
combustor temperature map 1221 may be created to show temperature
distributions in regions of the combustors 1220. Depending on the
area of interest, the sensors 1222 may be arranged around a plane
through a primary combustor flame zone or a turbine inlet
(combustor exit). A three-dimensional velocity map 1231 of gas flow
through a turbine diffuser 1230 may be constructed using
information from sensors 1232 arranged circumferentially around
multiple planar regions in the diffuser. An exhaust temperature map
1241 may be created using sensors 1242 to show temperature
distribution in a two-dimensional region of the turbine exhaust
1240. One skilled in the art will recognize that the described
techniques may be implemented with other sensor arrangements and
other gas turbine engine regions to yield additional useful
parameter maps.
[0100] An advanced methodology of tomographic principles is
utilized to extract a spatially resolved map in real time using a
few dozen individual paths of the signals. As described above, the
sensors may be acoustic sensors and speed of sound information on
each path is processed to estimate the average temperature over
that path length. At each time interval, representations of each of
the paths containing average temperature information are
tomographically mapped into the spatial distribution of the
temperatures at the measurement time and then updated for
subsequent measurement times. Information from the resulting
temperature map may be used in the engine control algorithm or to
maintain safety of engine operation and low emission levels.
[0101] In embodiments as discussed above and as shown in FIG. 13,
the transmitters and sensors 1310 are circumferentially distributed
around a cross section of the hot gas path of one or more turbine
regions 1305. The sensors and receivers may, in some embodiments,
be acoustic transceivers (sender/receiver combinations) arranged in
a plane through the combustor where those transceivers will send
and capture acoustic signals in real-time. While the disclosure
discusses the sensors and receivers with reference to acoustic
sensing techniques, one skilled in the art will understand that the
sensors and receivers may alternatively utilize laser-based tunable
diode laser absorption spectroscopy or another measurement
technology to determine an average temperature along a line path in
the combustor. In the case of acoustic transceivers, the
transmitted signals are used to determine an average speed of
sound, which is used to estimate an average temperature.
[0102] In the case of laser based tunable diode laser absorption
spectroscopy, several techniques for temperature measurement are
possible. Path averaged temperatures may be measured by probing two
different absorption lines for the same species while sweeping the
laser across the absorption spectrum. Laser absorption by gases
across the plane in certain infrared wavelength bands is
proportionate to species concentration and temperature and can be
solved to provide averaged path temperatures along each line.
Alternatively, the Full Width at Half Maximum (FWHM) of the probed
absorption line may be related to the Doppler line width of the
species. Other laser-based or other temperature measurement
techniques may be used without departing from the scope of the
disclosure.
[0103] In the case of temperature mapping, a tomographic mapping
module 1315 converts a plurality of average path temperatures into
a temperature map 1320 at each time interval that the temperatures
are sampled. The two-dimensional or three dimensional map includes
high spatial resolution isotherms and provides more valuable
information than separate average path temperature estimates for
interpretation of the engine health as well as for inputs to the
engine control algorithm. The temperature map 1320, together with
derived combustion quality information 1325, is transmitted to an
engine control unit 1330 that utilizes that information to control
the combustors and/or the gas turbine engine.
[0104] While described with reference to the construction of a
temperature map from average path temperature estimates, the
techniques described herein may be used to construct other two
dimensional or three dimensional maps from average values of paths.
For example, the estimated average velocities along transmitter
receiver paths may be used to construct a two-dimensional or three
dimensional map of local velocities using the similar methods.
[0105] Described herein are several different techniques for
mapping and extracting spatial information about a parameter from a
set of path averaged lines in a region. Those techniques include a
polynomial approximation method, a basis function method and a grid
optimization method. Each of those techniques is described in turn
below. While several of the descriptions refer to an exemplary
embodiment in which a gas flow temperature is measured, one skilled
in the art will recognize that the described techniques are
applicable to mapping other parameters where average values along
linear paths are available.
[0106] Polynomial Approximation Technique:
[0107] One way of accomplishing the task of converting a plurality
of average path temperatures to a temperature map is to approximate
the temperature profiles along each path with a polynomial and
then, through an iterative process as shown in the flow chart 1500
of FIG. 15, to adjust the parameters of each polynomial to minimize
errors. To do this, each path, such as path 1405 shown in FIG. 14A,
is initially assigned, in operation 1510 (FIG. 15), a temperature
function that includes scale factors and reflects the estimated
average temperature along the path. In the bi-linear profile 1400,
temperatures increase linearly from the end points 1415, 1420
(i.e., the transmit and receive points at the chamber walls) to
form a peak 1425 yielding a profile similar to the cross section of
a tent. The initial maximum temperature is at the peak and the
minimum (wall) temperatures are at either end. The distance 1430
from the transmit end point 14:15 to the peak 1425 is determined by
a midpoint scale parameter. The midpoint scale parameter may be
initially set to 50% of the path length by default.
[0108] The peak height 1410 defines the initial maximum temperature
along the path 1405 at the peak 1425. Initially, a peak height
scale factor may be set to the value of two times the average path
temperature.
[0109] The end points 1415, 1420 may be assumed to be constant and
are held at a constant level by the algorithm relative to a wall
temperature variable. The wall temperature variable may be selected
in several ways. In one example, a fixed value is manually entered.
In another example, a percentage of the average path temperature,
or the minimum path temperature, is used. In other embodiments, an
actual sensor such as a high temperature thermocouple is used to
input a wall temperature signal directly into the algorithm.
[0110] Bilinear integration is performed from the transmit point
1415 (wall temperature) to the mid-point 1425 (measured path
temperature iteratively computed scale factor) and back down to the
receive point 1420 (wall temperature).
[0111] The estimated path profile 1400 is then plotted, in
operation 1520, into a two dimensional grid representing the planar
area of the chamber 1401, as shown in FIG. 14B. That process is
repeated for each path, such as exemplary second path 1450. When
all temperatures have been plotted onto the grid, the grid contains
a sparse representation of the temperature map. As a result, there
are missing points on the grid in the open areas between paths. In
those open areas, a curve smoothing technique such as a Bezier
function is used to transform the set of known points into a
polynomial approximation of the actual temperature curve at
discrete points on the grid. After the grid is smoothed, line
integrations are performed along line paths, in operation 1530, and
compared to measured data in operation 1540. The result of that
comparison is used to adjust the scale factors in block 1570 for
the next iteration to minimize the error between measured and
estimated temperatures. The iterative process may be repeated
according to decision operation 1550 between 3 and 20 times to
produce a surface with the least error when compared to the
original measured average path temperatures.
[0112] The iterations are ended in operation 1560 when the errors
are below a preset maximum. While there is no specification for
absolute error or accuracy of the generated isothermal map, an
average path error value can be calculated to provide a confidence
factor for any given map. The average path error will range from 0
to 3-4% for a typical system in normal operation. If the mapping
plane and the physical factors have been optimally selected, this
can be used for a very accurate spatial map from the path averaged
temperature information.
[0113] Basis Function Technique:
[0114] Another technique for converting a plurality of average path
temperatures to a two dimensional temperature map is the use of
basis functions. In general, every continuous function in a
function space may be represented by a linear combination of basis
functions. In the presently described technique, portrayed in the
flow chart 1700 of FIG. 17, the temperature map is represented by a
linear combination of 2-dimensional basis functions derived from
thermocouple measurements.
[0115] The 2-dimensional basis functions are extracted, as shown in
operation 1710, from a large database of thermocouple temperature
measurements or other parameter measurements, using a statistical
procedure such as principal component analysis (PCA). The boundary
conditions are fixed/constant for the 2-dimensional basis functions
based on a manually entered fixed value, or on measured wall
temperatures. The technique finds weights for the basis functions
that minimize error on measured times of flight. In embodiments,
the weights are found iteratively.
[0116] In one embodiment, there are K two-dimensional basis
functions derived from the thermocouple measurements. There are
furthermore I acoustic paths i and t.sub.i mean temperatures, one
estimated from each time of flight measurement along an acoustic
path. For each basis function and path, the path temperatures are
sampled (operation 1720) into a vector along a length D of the
path. For each path 1, the sampled temperatures are collected in a
D.times.K matrix X.sub.i, as illustrated by the matrix 1600 of FIG.
16, which shows, for a single path, six temperature profiles for
six basis functions K.sub.1-K.sub.6, each sampled at five locations
D.sub.1-D.sub.5. For example, for the basis function K.sub.1 shown
in matrix 1600, five temperature samples are illustrated for five
sampled points D1 through D5 along the path. Similar matrices are
created for each of the other paths. The goal is to find (operation
1730) the combination of basis functions that best represents the
mean temperatures measured by the times of flight The weighted
combination of basis functions is given by the weight vector a
which can be found as:
arg min a i = 1 I 1 D a T X i 1 _ - t i 2 . ##EQU00006##
[0117] Grid Optimization Technique:
[0118] In an embodiment utilizing acoustic signals, the estimated
average path temperatures may be converted to a two dimensional
temperature map using a grid optimization technique shown in the
flow chart 1900 of FIG. 19, in which the 2-dimensional map is
segmented into multiple grid segments (operation 1910), such as the
grid segment 1820 shown in FIG. 18. The goal is to estimate the
value (temperature or velocity) in each grid segment. A grid
segment is defined as a region bounded by the horizontal and
vertical lines of the grid. The speed of the acoustic signal
throughout each grid segment is assumed to be uniform.
[0119] The distance covered by each acoustic path in traversing
each grid segment is initially calculated, at operation 1920. In
the example shown in FIG. 18, the distances within the grid segment
that are traversed by paths 1831, 1833, 1835 and 1837 are
determined. Since the total time of flight for each path and the
distance traversed by the path through each grid segment is known,
the time taken to travel through each grid segment along a path can
be calculated by solving following system of equations:
[ t 1 t 2 t n ] = [ d 11 d 12 d 1 m d 21 d 22 d 2 m d n 1 d n 2 d n
m ] [ x 1 x 2 x m ] ##EQU00007##
where n is an index of paths, m is an index of grid segments, t is
the time of flight for a given path, x is a coefficient of each
grid segment corresponding to a reciprocal of the speed of sound in
that grid segment
( 1 velocity ) ##EQU00008##
and d is the distance traversed by a path n through each grid
segment m.
[0120] A boundary condition is applied on the grid segment
coefficients corresponding to the boundary
x.sub.w=c
where w is a grid segment index corresponding to the wall and c is
a constant derived from the wall temperature.
[0121] To reduce the search space and limit the solved result to
within acceptable ranges, upper and lower bounds for the
coefficients are imposed based on the physical reality. For
example, the temperature of each grid segment may be restricted to
a value greater than room temperature and less than 1000.degree.
C.
[0122] The number of grids segments to be solved may greatly exceed
the number of path equations, making a large number of solutions
possible. In that case, additional optimization criteria such as
minimizing the difference between speeds of sound in neighboring
grid segments are imposed to obtain a smooth map which is also
close to reality.
[0123] After computing a value for a speed of sound for each grid
segment (operation 1930), temperature values are estimated for the
grid segments, and a temperature map may be constructed (operation
1940) using those values.
[0124] In embodiments, the above techniques may be employed in
controlling a gas turbine engine using temperature data. Once the
two-dimensional temperature map is computed, it is available in
real-time for the computation of information useful in controlling
the engine. For example, referring to FIG. 13, the tomographic
mapping module 1315 may compute the bulk mean temperature (average
temperature of the map), the distribution of temperature in the
plane (as a goodness function or as a profile), and a difference of
temperature between different baskets if the combustion system is a
can or can annular combustion system. That information is then
provided to the engine control unit 1330, which is intelligently
programmed to control engine parameters for optimum engine
performance (safety, performance and emissions).
[0125] Transceiver/transducers 32A-H and 34A-H (see FIG. 5)
transmit and receive acoustic signals that define acoustic paths.
Time of flight measurements along corresponding acoustic paths are
then used to generate a temperature map such as temperature map
1320 shown in FIG. 13. Each acoustic signal is transmitted and
received by transceiver/transducers 32A-H and 34A-H through a
waveguide associated with a transceiver/transducer. Although the
following description refers to the generation of a temperature
map, it is understood that the current invention is applicable to
any mapping method that utilizes measured line averages, such as
the average temperature on an acoustic path between
transceiver/transducers 32A-H and 34 A-H. In particular, the
current invention is applicable to the mapping of parameters of a
hot gas flow path such as gas flow temperature or velocity in flow
regions of gas turbine engines, for example.
[0126] Referring to FIG. 20, an exemplary cross sectional view is
shown of a plurality of acoustic paths or lines 2000 located in a
measurement space 2010 for a hot gas flow path. For purposes of
illustration, the hot gas flow path is constrained by a wall or
boundary 2015 such as in a combustor 20 although it is understood
that the hot gas flow path may be located in the turbine diffuser
1230 (see FIG. 12) or an exhaust stack. FIG. 20 depicts a plurality
of transceiver/transducers (i.e. transceivers), for example
transceivers 2030A-2030F, that generate acoustic signals that form
the acoustic paths 2000. Further, the acoustic paths 2000 cross at
intersection points 2050 in the measurement space 2010. In FIGS.
20-22, "Width" refers to a diameter of measurement space. As can be
seen in the figures, the width in the x and y axes is the same
thereby depicting a circular cross section for the measurement
space 2010 although it is understood that the measurement space
2010 may have a non-circular shape.
[0127] It is desirable to improve spatial resolution of a hot gas
flow path parameter map such as a temperature map. A technique for
improving spatial resolution of a temperature map is to increase
the number of transceivers that are utilized. However, this
requires several additional pairs of transceivers which increases
system cost from both a hardware and an installation standpoint.
Also, increasing the number of transceivers requires expensive data
acquisition and processing solutions thus increasing computational
costs. In addition, there is limited available space near a desired
measurement area of a gas turbine, thus limiting the number of
transceivers that may be installed.
[0128] As previously described, a temperature map may be generated
by utilizing a basis function technique wherein principal component
analysis is used to extract two dimensional basis functions from a
database of thermocouple temperature measurements. In another
embodiment, two dimensional Gaussian basis functions that are
centered on base points in the measurement space 2010 may be used
to generate a two dimensional temperature map. In particular, the
base points act as seat points for the basis functions.
Optimization techniques are then used to solve for the weight of
the Gaussian functions such that a fitting error relative to
measured mean temperatures along the lines is minimized. Referring
to FIG. 21, random base points 2040 (depicted as squares in FIG.
21) in the measurement space 2010 may be selected as the seat
points in one approach. However, use of random base points 2040
undesirably increases computational time.
[0129] In accordance with an embodiment of the invention, base
points 2060 (see FIG. 22) are selected that coincide with
intersection points 2050 of the acoustic paths generated by the
transceivers shown in FIG. 21. Thus, the geometry of the location
of the transceivers 2030A-2030F, such as the arrangement of the
transceivers about a portion of a gas turbine, defines the location
(in two or three dimensional coordinate space) of the base points
2060. The base points 2060 are used as center or seat points for
the basis function. In addition, starting and end points of each
acoustic path 2000 are also used as seat points. The location of
base points 2060 and starting/end (i.e. boundary points 2065)
points in turn defines the location and shape of the Gaussian (or
modified Gaussian) basis functions. In particular, a seat point
that has a relatively close neighboring seat point will have a
narrow basis function. Conversely, a seat point that has a
relatively farther neighboring seat point will have a broader basis
function. The goal is to control the influence of a basis point in
a particular location in a temperature map based on a density of
the seat points in that map location.
[0130] Referring to FIG. 23, transducers 2070A-2070F may be
arranged so to increase a number of intersections 2080 in a desired
region of interest 2090 for temperature mapping. For example,
transceivers 2070A-2070F may be arranged about the gas turbine 10
in order to focus and/or optimize the resolution of an area based
on prior information. Prior information may include knowledge of
the shape of the measurement space 2010 itself (i.e. circular or
non-circular shape) or the location of at least one region of
interest such as at least one hot section or at least one cold spot
or section in the measurement space 2010. The transceivers
2070A-2070F are then arranged about the gas turbine 10 in order to
increase the number of intersections 2080 in the region of interest
2090 thereby increasing a density of intersection points and base
points in the region of interest 2090 and forming additional base
points. In an embodiment, existing the transceivers 2030A-2030F may
be rearranged and/or additional transceivers may be used to
increase the density of intersection points in the region of
interest 2090.
[0131] A method will now be described for choosing sparse base
points. The method utilizes an optimization technique having an
objective and a plurality of constraints. Weight of the basis
functions is the value to be solved and is dependent on the average
temperatures of the acoustic paths 2000. For example, if the center
of a hot gas flow path is the hottest point, then the weight of
basis function corresponding to the seat point located in the
center of the hot gas flow path has a large weight. The objective
is to maximally fit the base points weight to the line average
temperatures. In an embodiment, a constraint is that upper and
lower bounds based on a physical characteristic of the hot gas flow
path may be used for weighting the basis functions. For example,
the maximum and minimum temperatures generated in the hot gas flow
path may be used as constraints. Another constraint may be to
minimize the differences in the weighting of basis functions of
relatively close seat points so as to enable smooth mapping.
Alternatively, this can also be added to the objective itself
wherein the objective is to minimize differences in the weighting
of basis functions of relatively close seat points.
[0132] Referring to FIG. 24, an exemplary temperature map 2100 is
shown wherein the map 2100 is generated without a constraint that
minimizes differences in weighting functions. In particular, the
map 2100 depicts temperature regions 2110, 2120 and 2130 that are
separate from each other thus depicting substantial changes in
temperature in the map 2100. Referring to FIG. 25, an exemplary
temperature map 2140 is shown wherein the constraint for minimizing
differences in weighting functions is utilized. As can be seen in
FIG. 25, the temperature regions 2110, 2120, 2130 are now arranged
such that the substantial changes in temperature in the map are
reduced.
[0133] In the method of the current invention, K estimation points
that include intersection points 2050 and boundary points 2065 are
identified. The values at the estimation points are solved and the
method is posed as a constrained least squares problem. The
objective it to minimize line fit error relative to the measured
mean values. Further, boundary conditions are imposed by an
equality criterion. The weight of the basis functions is given by
Equation (1):
argmin y 1 , , y K l = 1 L 1 T l x k .di-elect cons. l y k - h l 2
subject to { y k = b k for x k on boundary lb .ltoreq. y k .ltoreq.
ub for all k ##EQU00009##
wherein the measured line temperature averages are given by h.sub.l
for each line l. Further, there are T.sub.l estimation points on
line l, y.sub.k is the temperature at estimation point x.sub.k and
lb and ub are lower and upper bounds, respectively, for
y.sub.k.
[0134] A Gaussian radial basis function (i.e. Gaussian RBF) is then
built for each estimation point. The Gaussian RBF is given by
Equation (2):
e.sup.-.lamda.r.sup.2
wherein r is the distance from a mapping point from the Gaussian
RBF center and .lamda. is a scaling factor for the Gaussian RBF.
The scaling factor .lamda. is used to adjust a flatness of the
Gaussian RBF based on the nearest estimation point wherein the
farther the nearest neighbor, the flatter the Gaussian RBF. In
particular, the Gaussian RBF is made flatter (i.e. a smaller
.lamda.) the further the nearest neighboring base point and
narrower (i.e. a larger .lamda.) the closer the nearest the
neighboring base point. The weighted sum of all Gaussian RBFs is
then used in generating the temperature map.
[0135] The constraint for minimizing differences in weighting of
basis functions of relatively close seat points may be obtained via
Equation (1) by equating h.sub.l to zero and wherein the summation
over y.sub.k is made as a difference between neighboring points.
Alternatively, the constraint is given by Equation (3):
argmin y 1 , , y k p = 1 P y k - y p 2 ##EQU00010##
where there are P close point pairs and y.sub.p corresponds to a
point closer to y.sub.k whose difference is to be minimized.
[0136] Referring to FIG. 26, a flowchart 2150 depicting a method
for optimizing a number of base points in accordance with the
invention is shown. At Step 2160, the average temperature for each
acoustic path 2000 is calculated. Next, the intersection points
2050 of all the acoustic paths 2000 are calculated at Step 2170.
The intersection points 2050 may be calculated using known
geometric operations for calculating the intersection of two line
segments. At Step 2180, additional base points are generated to
apply apriori information. The additional base points are
independent of the base points 2060 generated due to transceiver
locations and are generated to include apriori information. For
example, if a temperature at a location in the hot gas flow path is
known, a base point is added that corresponds to the location. The
weight of a Gaussian RBF centered on the added base point is then
set equal to the known temperature. In another example, base points
may be added to include apriori information regarding known
boundary condition information such as a known temperature and/or
velocity near the boundary 2015 of the combustor 20. In particular,
the temperature near the boundary 2015 is considered when
generating a temperature map. Uniformly distributed base points are
then generated near the boundary 2015. Weights of Gaussian RBFs
centered on each of the generated base points are then set equal to
the known wall temperature. Next, Gaussian basis functions are then
built for each base point at Step 2190. The method then includes
solving for the weight of the Gaussian RBFs which meets the
constraints and satisfies the objective at Step 2200. In alternate
embodiments, other types of basis functions may be used such as
subgaussian, supergaussian, splines and other basis functions.
Further, combinations of different types of basis functions may be
used. For example, a first type of basis function may be used for
boundary points and another type of basis function may be used for
intersection points.
[0137] The current invention provides a method for generating
sparse base points that improves computational speed and enhances
temperature map quality and resolution for a hot gas flow path
while minimizing the number of transceivers. Further, the current
invention enables configuration of the transceivers for use in
applications other than gas turbines such as gasifiers.
[0138] Although various embodiments that incorporate the teachings
of the present invention have been shown and described in detail
herein, those skilled in the art can readily devise many other
varied embodiments that still incorporate these teachings. The
invention is not limited in its application to the exemplary
embodiment details of construction and the arrangement of
components set forth in the description or illustrated in the
drawings. However, the various aspects of the present invention
described more fully herein may be applied to other instances where
a profile map of values in a region is determined based on average
values along linear paths through the region. The invention is
capable of other embodiments and of being practiced or of being
carried out in various ways. While acoustic and laser sensors are
discussed, other measurement techniques may be used. Also, it is to
be understood that the phraseology and terminology used herein is
for the purpose of description and should not be regarded as
limiting. The use of "including," "comprising," or "having" and
variations thereof herein is meant to encompass the items listed
thereafter and equivalents thereof as well as additional items.
Unless specified or limited otherwise, the terms "mounted,"
"connected," "supported," and "coupled" and variations thereof are
used broadly and encompass direct and indirect mountings,
connections, supports, and couplings. Further, "connected" and
"coupled" are not restricted to physical or mechanical connections
or couplings.
* * * * *