Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
AUTOMATED TUNING OF MULTIPLE FUEL GAS TURBINE
COMBUSTION SYSTEMS
Cross-Reference to Related Applications
[0001] This application is a continuation-in-part of US Application Serial No.
13/542,222,
filed on July 5, 2012, which is a continuation-in-part of US Application
Serial No. 12/463,060
filed on May 8, 2009. This application also claims the benefit of US
Application Serial No.
61/601,871, filed on February 22, 2012.
Technical Field
[0002] The present disclosure relates to an automated system for sensing the
operating
condition of a combustion system and to making automated, preset adjustments
to achieve
desired operating conditions of the turbine. The present disclosure also
relates to turbines
operating using fuels having varying thermophysical properties.
Background
[0003] Lean premixed combustion systems have been deployed on land based and
marine
fuel turbine engines to reduce emissions, such as NOx and CO. These systems
have been
successful and, in some cases, produce emission levels that are at the lower
limits of
measurement capabilities, approximately 1 to 3 parts per million (ppm) of NOx
and CO.
Although these systems are a great benefit from a standpoint of emission
production, the
operational envelope of the systems is substantially reduced when compared to
more
conventional combustion systems. As a consequence, the control of fuel
conditions,
distribution and injection into the combustion zones has become a critical
operating parameter
and requires frequent adjustment, when ambient atmospheric conditions, such as
temperature,
humidity and pressure, change. In addition to ambient condition changes,
variation in the fuel's
thermophysical properties will also change operational conditions leading to
another source
of variation that requires adjustment of the fuel turbine operational
settings. The re-adjustment
of the combustion fuel conditions, distribution and injection is termed
tuning.
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[0004] Controlled operation of a combustion system generally employs a
manual setting of
the operational control settings of a combustor to yield an average
operational condition. These
settings may be input through a controller, which as used herein shall refer
to any device used to
control the operation of a system. Examples include a Distributed Control
System (DCS), a fuel
turbine controller, a programmable logical controller (PLC), a stand-alone
computer with
communication to another controller and/or directly to a system.
[0005] These settings are satisfactory at the time of the setup, but
conditions may change
when tuning issues arise and cause an unacceptable operation in a matter of
hours or days.
Tuning issues are any situation whereby any operational parameters of a system
are in excess of
acceptable limits. Examples include emissions excursion outside of allowable
limits, combustor
dynamics excursion outside of allowable limits, or any other tuning event
requiring adjustment
of a turbine's operational control elements. Other approaches use a formula to
predict emissions
based on fuel turbine's operating settings and select a set point for fuel
distribution and/or overall
machine fuel/air ratio, without modifying other control elements, such as fuel
temperature.
These approaches do not allow for timely variation, do not take advantage of
actual dynamics
and emission data or do not modify fuel distribution, fuel temperature and/or
other turbine
operating parameters.
[0006] Another variable that impacts the lean premixed combustion system is
fuel
composition. Sufficient variation in fuel composition will cause a change in
the heat release of
the lean premixed combustion system. Such change may lead to emissions
excursions, unstable
combustion processes, or even blow out of the combustion system. Over the last
twenty years,
many economic and technological changes have occurred which have led to
paradigm shifts in
key operational inputs into fuel turbine combustion systems ¨ namely fuel
compositions
requirements. One example of a fuel that is of considerable significance in
this area is the use of
liquefied natural gas (LNG).
[0007] LNG is becoming increasingly more prominent in the United States,
Asia and South
America. An inherent feature of LNG is variable gas composition as a "batch"
of LNG is
consumed. Since gas constituents with different volatilities (methane, ethane,
propane, etc.) are
vaporized at different rates (methane being one of the fastest to volatilize),
methane
concentrations typically continue to decrease as a "batch" of LNG is vaporized
and subsequently
consumed.
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[0008] In addition, fuel producers are continually faced with economic and
operational
pressures to deliver "non-pipeline quality" fuel to their consumers. To this
end, some suppliers
have gone as far as to incentivize their customers to burn "off-spec" fuel by
offering a reduction
in the price per million BTU ($1 MMBTU). As used herein, the concept of
multiple-fuel
burning combustion turbines will be discussed in terms of "pipeline quality"
and "non-pipeline
quality" fuels. However, it should be understood that while these are common
terms to refer to a
primary fuel source and a secondary fuel source or sources, they are intended
to merely define
first and second fuel sources, which may all be of pipeline quality or may not
contain any
pipeline quality fuel. In many cases, the "pipeline quality" fuel may be more
expensive than
"non-pipeline quality" but this is not required,
100091 On marine based equipment each refueling of liquid fuel is an
opportunity for a
change in its physical properties depending on the source and grade of the
fuel. Such changes
frequently impact emission levels of the gas combustion turbines and may also
impact the base
load points of the propulsion or power plant.
[0010] These above criteria have caused increased pressure on gas turbine
operators to
operate their equipment using "non-pipeline quality" fuel or non-standard
distillate. However,
consumption of large quantities of this "off-spec" fuel may have detrimental
effects on the
combustion turbine system.
[0011] In addition, mis-operation of the combustion system manifests itself
in augmented
pressure pulsations or an increase in combustion dynamics (hereinafter,
combustion dynamics
may be indicated by the symbol "SP"). Pulsations can have sufficient force to
destroy the
combustion system and dramatically reduce the life of combustion hardware.
Additionally,
improper tuning of the combustion system can lead to emission excursions and
violate emission
permits. Therefore, a means to maintain the stability of the lean premixed
combustion systems,
on a regular or periodic basis, within the proper operating envelope, is of
great value and interest
to the industry. Additionally, a system that operates by utilizing near real-
time data, taken from
the turbine sensors, would have significant value to coordinate modulation of
fuel composition
fuel distribution, fuel or distillate inlet temperature and/or overall machine
fuel/air ratio.
[0012] While real-time tuning of a combustion system can provide tremendous
operational
flexibility and protection for turbine hardware, a combustion system may
concurrently
experience a number of different operational issues. For example, most turbine
operators of lean
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premixed combustion systems are concerned with exhaust emissions (NOx and CO)
as well as
combustor dynamics. It is not uncommon for both high NOx emissions and high
combustor
dynamics to coexist on a turbine. Additionally, tuning in response to one
concern can make
other constraints worse, for example tuning for low NOx can make combustor
dynamics worse,
tuning for high CO can make NOx worse, etc. It would be beneficial to provide
a system
whereby an algorithm is used to compare the current status of all tuning
concerns, rank each
concern in order of importance, determine the operational concern of most
interest, and
subsequently commence automated tuning to remediate this dominant operational
concern.
100131 Since
many operators are incentivized to consume as much of the less expensive
"non-pipeline quality" fuel as possible while mixing the non-pipeline quality
fuel with pipeline
quality natural fuel (and sending the resultant mixture to their fuel turbine
combustion system), a
means of real-time optimization of the ratio of non-pipeline quality to
pipeline quality fuel is also
desired.
Summary
100141 'The
present disclosure includes a method for optimizing the ratio of non-pipeline
quality to pipeline quality fuel or marine distillate (fuel blend ratio) for
subsequent consumption
in a fuel turbine consumption system of the comprising providing a first fuel
source and a second
fuel source. The method further includes supplying fuel to a combustion
turbine in a blend of
fuel from the first source and second source. The method also includes sensing
the operational
parameters of the gas turbine and determining whether the operational
parameters are within
preset operational limits. Still further, the method includes adjusting the
blend of the first fuel
source and the second fuel source, based on whether the operational parameters
are within the
preset operational limits.
100151 The
present disclosure also includes a tuning system for automated control of' a
gas
turbine fuel composition through automated modification of a ratio of fuel
gas. The tuning
system comprises operational turbine controls for operational control elements
of the turbine, the
turbine controls controlling at least one of turbine fuel distribution or the
fuel temperature.
Further, the system includes a tuning controller communicating with the
controls configured to
tune the operation of the turbine in accordance with receiving operational
data about the turbine,
providing a hierarchy of tuning issues, determining whether sensed operational
data is within
predetermined operational limits and producing one or more indicators if said
operational data is
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not within predetermined operational limits. The system further includes
ranking the one or
more indicators to determine dominant tuning concern. Still further, the
system includes
providing a blend of fuel to a level blend ratio controller, the blend having
fuel from at least one
of a first and second fuel source ratio controller, the fuel blend ratio
controller adjusting the ratio
of the first fuel source and the second fuel source according to the blend,
[0016] In a further aspect of the disclosure, the system performs a method
for determination
of the dominant fuel turbine combustion system tuning scenario through the use
of Boolean
hierarchical logic and multiple levels of control settings.
[0017] In another aspect of the disclosure, the method performed relates to
automated control
of the fuel turbine inlet fuel temperature through automated modification of
the fuel temperature
control set point within a Distributed Control System (DCS),
[0018] In a still further aspect of the disclosure, a method for automated
control of a fuel
turbine inlet fuel temperature is defined by automated modification of the
fuel temperature
control set point within the fuel temperature controller. In another aspect of
the disclosure a
method for communicating turbine control signals to a fuel turbine controller
is accomplished
through the use of an existing fuel turbine communication link with an
external control device,
such as, for example a MODBUS Serial or Ethernet communication protocol port
existing on the
turbine controller for communication with the Distributed Control System
(DCS).
[0019] In a still further aspect of the disclosure a method for
modification of a fuel turbine
combustion system is defined by a series of auto tuning settings via a user
interface display,
which utilizes Boolean-logic toggle switches to select user-desired
optimization criteria. The
method is preferably defined by optimization criteria based on Optimum
Combustion Dynamics,
Optimum NOx Emissions, Optimum Power, Optimum Heat Rate, Optimum CO Emissions,
Optimum Heat Recovery Steam Generator (HRSG) Life, Optimum Gas Turbine Fuel
Blend
Ratio or Optimal Gas Turbine Turndown Capability whereby toggling of this
switch changes the
magnitude of the combustor dynamics control setting(s).
[0020] In a still further aspect of the disclosure, and in conjunction with
the control scheme
outlined above, the controller can be directed to continuously maximize the
non-pipeline quality
fuel blend ratio. Conversely, if tuning issues arise, the tuning issues cannot
be resolved by
adjustments to the turbine parameters outlined above, the fuel blend ratio can
be altered/reduced.
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Brief Description of Drawings
[0021] For the purpose of illustrating the disclosure, the drawings show
forms that are
presently preferred. It should be understood that the disclosure is not
limited to the precise
arrangements and instrumentalities shown in the drawings of the present
disclosure.
100221 Fig. 1 shows an exemplary embodiment of a schematic representation
of an
operational plant communication system encompassing the fuel turbine engine
system and
incorporating a fuel turbine tuning controller, utilizing a DCS as a central
control hub.
[0023] Fig. 2 shows a schematic representation of an alternate embodiment
of an operational
plant communication system encompassing the fuel turbine engine system,
incorporating a fuel
turbine tuning controller, where the tuning controller is the central
communication hub.
[0024] Fig. 3 shows a schematic representation of a further alternate
embodiment of an
operational plant communication system encompassing the fuel turbine engine
system,
incorporating a fuel turbine tuning controller, where the fuel turbine tuning
controller is the
central communication hub.
[0025] Fig. 4 shows an exemplary embodiment of a functional flow chart for
the operation of
a tuning controller according to the present disclosure.
[0026] Fig. 5 shows an exemplary embodiment of a user interface display for
selecting the
optimization mode within the present disclosure.
[0027] Fig. 6 shows an exemplary schematic of the inter-relationship of
various optimization
mode settings.
[0028] Fig. 7 shows an exemplary overview schematic of the process steps
utilized to
determine the alarm signals triggered according to the present disclosure.
[0029] Fig. 8 shows an exemplary process overview of the steps to determine
allowable
turbine tuning parameters.
[0030] Fig. 9 shows a further detailed exemplary process according to the
steps shown in
Fig. 8.
[0031] Fig. 10 shows a detailed exemplary schematic of steps utilized to
determine the
dominant tuning concern according to the present disclosure.
[0032] Fig. 11 shows a first example schematic of the determination of the
system's
dominant tuning concern, given various alarm inputs into the present
disclosure.
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[0033] Fig. 12 shows a second example schematic of the determination of the
system's
dominant tuning concern, given various alarm inputs into the present
disclosure.
[0034] Fig. 13 shows a third example schematic of the determination of the
system's
dominant tuning concern, given various alarm inputs into the present
disclosure.
[0035] Fig. 14 shows a fourth example schematic of the determination of the
system's
dominant tuning concern, given various alarm inputs into the present
disclosure.
[0036] Fig. 15 shows a fourth example schematic of the determination of the
system's
dominant tuning concern, given various alarm inputs into the present
disclosure.
[0037] Fig. 16 shows a first operational example of operational tuning of a
fuel turbine
engine system as contemplated by the present disclosure.
[0038] Fig. 17 shows a second operational example of operational tuning of
a fuel turbine
engine system as contemplated by the present disclosure.
[0039] Fig. 18 shows a third operational example of operational tuning of a
fuel turbine
engine system as contemplated by the present disclosure.
[0040] Fig. 19 shows a fourth operational example of operational tuning of
a fuel turbine
engine system as contemplated by the present disclosure.
[0041] Fig. 20 shows a first exemplary schematic representation of the
function of the tuning
controller of the present disclosure in maintaining the tuning of the turbine
system.
[0042] Fig. 21 shows a second exemplary schematic representation of the
function of the
tuning controller of the present disclosure in maintaining the tuning of the
turbine system.
Detailed Description
[0043] The present disclosure generally relates to systems and methods for
tuning the
operation of combustion turbines. In the depicted embodiments, the systems and
methods relate
to automatic tuning of combustion turbines, such as those used for power
generation. Persons of
ordinary skill in the art will appreciate that the teachings herein can be
readily adapted to other
types of combustion turbines. Accordingly, the terms used herein are not
intended to be limiting
of the embodiments of the present invention. Instead, it will be understood
that the embodiments
of the present disclosure relate generally to the field of combustion
turbines, and in particular for
systems, methods and computer readable media for tuning of combustion
turbines.
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10044] Fig. 1 is a communication diagram for a gas combustion turbine
engine (not shown),
within which a tuning controller 10 of the present disclosure operates. A
communication link or
hub is provided to direct communication between various elements of the
turbine system. As
shown, a communication link is a Distributed Control System (DCS) identified
by the numeral
20, and provides a link to the various elements of the system. However, the
operational elements
of the turbine may be linked directly to each other, without the need for a
DCS. Most of the
turbine control is performed through the DCS 20. A turbine controller 30
communicates directly
with the turbine (as shown) and with the DCS 20. In the present disclosure,
information relevant
to turbine operation, e.g., turbine dynamics, turbine exhaust emissions, etc.
is directed through
the DCS 20 to other elements of the system, such as the tuning controller 10.
The tuning
controller 10 is contemplated to be a stand-alone PC used to run as a
programmable logical
controller (PLC). In the present disclosure, information relevant to turbine
operation is directed
through the tuning controller 10. This relevant information is also referred
to as the turbine's
operational parameters, which are parameters that are measured, by way of
various types and
number of sensors, to indicate operational status of various aspects of the
turbine. These
parameters can be fed as inputs into the autotuning controller. Examples of
operation parameters
include combustor dynamics, turbine exhaust emissions, and tubing exhaust
temperature, which
is generally influenced by the overall fuel/air ratio of the turbine.
100451 Referring now to Figs. 1, 2, and 3, the tuning controller 10 is
preferably a separate
computer from the turbine controller 30 that is in constant communication with
the turbine
controller 30, either directly or through the DCS 20. The signals from the
tuning controller 10
may be transferred to the turbine controller 30 or other controls within the
system by the use of
an external control device, such as a MODBUS Serial or Ethernet communication
protocol port
existing on or added to the system. In an alternate configuration, the tuning
controller 10 may be
embedded in the turbine control system should a plant configuration not
include a DCS system
and use the controller as a distributed control system.
100461 The relevant operational parameters are received from sensor means
associated with
the turbine. For example, the turbine exhaust emission reading is taken from
stack emissions by a
continuous emissions monitoring system (CEMS) 40, and sent to the tuning
controller 10 and/or
the turbine controller 30. Combustion dynamics are sensed using a dynamic
pressure sensing
probe located within the combustion region of the turbine combustor. As shown,
a continuous
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dynamics monitoring system (CDMS) 50 is provided and communicates with the DCS
20 and
controller 60. The CDMS 50 preferably uses either direct mounted or wave guide
connected
pressure or light sensing probes to measure the combustion dynamics. Another
relevant
operational parameter is the fuel temperature, which is sensed at the fuel
heating controller 60.
The fuel temperature information is directed to the tuning controller 10
through the DCS 20 from
the fuel heating controller 60. Since part of the tuning operation may include
adjustment of the
fuel temperature, there may be a two-way communication between the tuning
controller 10
and/or turbine controller 30 from the fuel heating unit 60, via the DCS 20.
The DCS 20 also
communicates with a fuel blend ratio controller 70 to adjust the ratio of
pipeline quality fuel to
non-pipeline quality fuel (for subsequent consumption within the turbine). The
system may also
be used to adjust blends of other fuels for turbines that are operating on
liquid fuels, such as a
turbine in a marine application or distillate fired power generation
application. There exists, as
part of this disclosure, communication between the fuel blend ratio controller
70 and the tuning
controller 10, via the DCS 20. For purposes of this disclosure, "pipeline
quality" and "non-
pipeline quality" fuel or fuel shall be used to refer to first and second
types of fuels having
different characteristics, such as price, level of refinement or other
characteristics that may
influence the decision to prefer one fuel over the other fuel.
[0047] Fig. 2 shows a communication diagram of an alternate embodiment of a
system that is
similar to Fig. 1, with the exception that the DCS 20 is removed from the
communication
network. In this setup, the tuning controller 10 communicates directly with
all other
devices/controllers (30, 40, 50, 60 and/or 70). For purposes of the present
application, the tuning
process will be described with the communication layout as determined in Fig.
1; however, the
below-described tuning process can also be applied to the communication
schematic identified in
Fig. 2.
[0048] Fig. 3 shows a communication diagram of a second alternate
embodiment of a system
that is similar to Fig. 2, except that the DCS 20 is removed from the
communication network. In
this setup, the turbine controller 30 communicates directly with all over
devices/controllers (10,
40, 50, 60 and/or 70). For purposes of the present application, the tuning
process will be
described with the communication layout as determined in Fig. 1; however, the
below-described
tuning process can also be applied to the communication schematic identified
in Fig. 1
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[0049] Relevant operational data from the turbine may be collected at least
several times per
minute. This frequency of data collection allows for near real-time system
tuning. Most relevant .
turbine operational data is collected by the tuning controller in near real-
time. However, the
turbine exhaust emissions data is typically received from the CEMS 40 by the
tuning controller
with a 2 to 8 minute time lag from current operating conditions. This time lag
necessitates the
need for the tuning controller 10 to receive and buffer relevant information,
for a similar time
lag, before making operational tuning adjustments. This tuning controller 10
tuning adjustment
time lag assures that all of the operational (including exhaust emissions)
data is representative of
a stable turbine operation before and after any adjustments are made. Once the
data is deemed
stable, the tuning controller 10 determines whether there is a need for
adjustment of operational
control elements to bring the tuning parameters into acceptable ranges. The
procedure for
determining whether any tuning adjustments are necessary will be described in
further detail
below. If no adjustment is necessary, the tuning controller 10 maintains the
current tuning and
waits to receive the next data set. If changes are desired, tuning commences,
[0050] In a situation where there are no tuning adjustments necessary to
correct operating
conditions if the turbine, and if there is sufficient margin in the key
operational characteristics of
the turbine (e.g. exhaust emissions and combustor dynamics), the tuning
controller 10 can send a
command directly to the fuel ratio controller 70 as shown in Fig. 2, or
alternatively, to the fuel
ratio controller 70 through the DCS 20 as shown in Fig, 1, to increase the
ratio of non-pipeline
quality fuel to pipeline quality fuel or alternative fuels such as distillate.
As used herein, control
elements or operational control elements are control inputs that can be
manipulated by the tuning
controller 10 to produce a change in the operational parameters of a turbine.
These elements can
either reside with the turbine controller 10, within the plant distributed
control system (DCS), or
within an external controller that controls the properties of inputs into the
turbine (such as fuel
temperature). Examples of operational control elements include combustor fuel
splits, turbine
fuel/air ratio, and inlet temperature.
[0051] All determinations of the need for turbine tuning are performed
within the tuning
controller 10. The tuning operation is started based on an indicator, such as
an "alarm" condition
that is created by receipt of operational parameter data outside of acceptable
limits of preset
operational criteria. In order for the tuning operation to be initiated, the
alarm ¨ and thus the
operational parameter data anomaly ¨ must continue for a predetermined period
of time.
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[0052] One example of a tuning adjustment is the variation of the fuel
nozzle pressure ratio
to adjust combustion dynamics. With the requirement of higher firing
temperatures to achieve
greater flame temperatures and efficiency, turbine combustors must release
more energy in a
given combustor volume. Better exhaust emissions are often achieved by
increasing the mixing
rate of fuel and air upstream of the combustion reaction zone. The increased
mixing rate is often
achieved by increasing the pressure drop at the fuel nozzle discharge. As the
mixing rate
increases in combustors, the turbulence generated by combustion often leads to
noise within the
combustor and may lead to the generation of acoustic waves. Typically,
acoustic waves are
caused when the sound waves of the combustion flames are coupled with the
acoustic
characteristics of the combustor volume or the fuel system itself.
[0053] Acoustic waves may affect the internal pressure in the chamber.
Where combustor
pressure inside a combustion chamber, near a fuel nozzle rises, the rate of
fuel flowing through
the nozzle and the accompanying pressure drop decreases. Alternatively, a
decrease in pressure
near the nozzle will cause an increase in fuel flow. In cases where a fuel
nozzle pressure drop
allows fuel flow oscillation, a combustor may experience amplified pressure
oscillations. To
combat the pressure oscillations within the combustor, combustion dynamics are
monitored and
the fuel air ratio and fuel nozzle pressure ratio may be modified to reduce or
eliminate unwanted
variations in combustor pressure, thereby curing an alarm situation or
bringing the combustion
system back to an acceptable level of combustion dynamics.
[0054] As shown in Fig. 4, the data received from the CDMS 50, CEMS 40,
fuel temperature
controller 60 and other relevant turbine operating parameters from the turbine
controller 30 may
be directed through the DCS 20 to the tuning controller 10. These input values
are then
compared to standard or target operational data for the turbine. The stored
operational standards
are based, at least in part, on the operational priority settings for the
turbine in the form of tuning
alarm levels, as will be described in more detail below. The priority settings
are defined by user
selected inputs on the main user interface 12 of the tuning controller 10, as
shown graphically in
Fig. 5. Based on the priority settings, a series of adjustments are made to
the operation of the
turbine by the turbine controller 10 connected through the DCS 20. The
adjustments are directed
to the control means, including the fuel heating unit 60, fuel blend ratio
controller 70, and
various other operational elements of the turbine controller 30.
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[0055] In addition to adjusting the tuning parameters described above, the
turbine controller
will also determine if there is sufficient margin amongst the operational
standards to adjust the
fuel blend ratio. Typically, as described in further detail below, the amount
of non-pipeline
quality fuel will be increased if the system is found to be well within the
tuning limits, and the
amount of pipeline quality fuel will be increased if tuning alarms are
activated.
[0056] The interface display 12 shown in Fig. 5 is the main user interface
display that end
users will operate to determine tuning alarm levels. The interface 12 is
comprised of switches
(each having an On/Off indication). These switches allow the user to specify
the desired tuning
priorities for the operation of the turbine. In the embodiment shown, the
switched operational
priorities include optimum NOx emissions 14, optimum power 16, optimum
combustor
dynamics 18, and optimum fuel blend ratio 19. Each of these switches is set by
the user to adjust
the preferred operation of the turbine. Switching the switches from "Off" to
"On" operates to
change the alarm limits for each parameter. Within the tuning controller 10
are functions that
modify operations within the turbine, based on priorities set by the switches.
The priorities may
also be governed logic implemented thorough hardware configured to perform the
necessary
logic operations in addition to user selected priorities. For example, in the
embodiment
described here, if both the optimum NOx emissions switch 14 and the optimum
power switch 16
are set to "On", the controller 10 will run in the optimum NOx mode, not
optimum power. Thus,
to run in optimum power mode, the optimum NOx emissions switch 14 must be
"Off'. In the
embodiment shown, optimum power 16 may only be selected if optimum NOx 14 is
in the off
position. Optimum dynamics 18 can be selected at any time. The optimum fuel
blend ratio 19
switch may be "On" when any of the switches are "On" and will overlay other
operational
parameters. It is explicitly noted that other User-Interface Toggle Switches
(not shown) may be
used, including parameters such as Optimum Heat Rate, Optimum CO emissions,
Optimum Heat
Recovery Steam Generator (HRSG) Life, Optimal Gas Turbine Turndown Capability,
etc.
[0057] Fig. 6 shows a graphical representation of the interrelationship of
the interface display
switches. As shown, switching one parameter "On" will alter the alarm limits
to a different level
than their "Off' level. In the example shown in Fig. 6, the alarm limits are
shown with both
Optimum NOx and optimum power in the "On" position and in the "Off" position.
These points
on the graph are then modified by the selection of optimum dynamics
(represented throughout by
the symbol 6) in either the "On" or "Off' position. The points shown on the
graph of Fig. 6
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represent an exemplary set of limits for dynamics, based on the user's
selected operational
priorities.
[0058] Activating the Optimum Fuel Blend Ratio switch 19 of Fig. 4 will not
affect the
overall tuning parameters of the controller. Rather, activating the Optimum
Fuel Blend Ratio
switch 19 will overlay as second set of allowable limits upon the limits
imparted by the other
switches 14, 16, 18. The second set of limits is based on the existing limits
set by Optimum
NOx, Power and Dynamics, but provides for an operational envelope within these
limits. If the
turbine is operating within the limits set by activating the Optimum Fuel
Blend Ratio switch 19,
the controller 10 will adjust the fuel blend ration to increase the amount of
non-pipeline quality
fuel. Conversely, if the turbine is operating outside of the limits set by
activating the Optimum
Fuel Blend Ratio switch 19, the controller will adjust the fuel blend ratio to
increase the amount
of pipeline quality fuel. Adjustments to the fuel blend ratio arc done during
the normal tuning
progression described with respect to Fig. 4.
[0059] Fig. 4, shows a representation of the logical flow of the
determinations and
calculations made within the tuning controller. 10. The tuning controller 10
receives the actual
operating parameters of the turbine through the turbine controller 30,
combustor dynamics
through the CDMS 50, and the turbine exhaust emissions through the CEMS 40.
This sensor
data is directed to the tuning controller 10, either directly from the
elements 40, 50 and 60
mentioned above, or through the DCS 20. The received sensor data is compared
to stored
operational standards to determine if the turbine operation is conforming to
the desired settings.
The operational standards are stored in the tuning controller 10 in the form
of alarm levels,
where normal operation of the turbine will return operational data for each
parameter that is
between the high and low alarm levels set for that parameter. The alarm levels
for the
operational standards are based on the preset operational priorities of the
turbine, defined by the
user switches 14, 16, 18, 19 on the main user interface display 12 of the
tuning controller 10, as
discussed above with respect to Fig. 5.
[0060] Based on the preset operational priorities, a hard-coded
hierarchical Boolean logic
approach that is coded into the tuning controller 10 determines the dominant
tuning criteria based
on operational priorities. From this logical selection, the tuning controller
10 implements a fixed
incremental adjustment value for changing an operational parameter of the
turbine within a
maximum range of adjustment (e.g., high and low values). The tuning changes
are made in a
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consistent, pre-determined direction over a pre-determined increment of time
and are dependent
on the dominant tuning criteria at the time. It is contemplated that no
instant formulaic or
functional calculations are made to determine the direction, magnitude and
spacing of tuning
adjustments; rather, the magnitude of the incremental adjustments, the
direction of the
adjustments, the time span between adjustments, and the maximum range for the
adjustments for
each control element are stored in the tuning controller 10 and selected based
on the alarm
returned and user's operational priorities. This criteria is preferably stored
in the tuning
controller 10 as tuning control constrains and may be modified from time to
time as desired by
the user.
100611 As shown in Fig. 4, the tuning controller 10 determines whether the
emissions are in
compliance 100 and whether the combustor dynamics are at acceptable levels 102
by comparing
the operating parameters received from the CDMS 50 and CEMS 40 respectively,
to the
operational standards and alarm levels saved in the tuning controller 10 as
discussed above. If
both are in compliance with the set operational standards, no further
corrective action is taken
and the tuning controller 10 waits for the next data set from the CEMS 40 or
the CDMS 50, or
for other operational data from the turbine controller 30. If the data
received from the CEMS 40
or the CDMS 50 is non-conforming with the operational standards, i.e. above or
below alarm
levels as is the case with step 104 of Fig. 2, the tuning operation moves to
the next tuning step of
first determining the dominant tuning concern 106. The logical adjustment of
turbine operation
is defined by the dominant tuning criteria 106, which is based, at least in
part, on the preset
operational priorities set within the user interface 12, as will be discussed
below with respect to
Fig. 10.
10062] Once the dominant tuning concern is determined, the tuning
controller 10 will attempt
to correct the operational parameter to ensure that the levels are within the
operational standards
stored in the tuning controller 10. In a preferred operation, to correct a
tuning issue, the tuning
controller 10 will first attempt to incrementally change the turbine combustor
fuel splits 108. For
a machine fueled with liquid fuel, fuel splits are substituted by atomizing
air pressure regulation
and fuel flow. The fuel split determines the distribution of the fuel flow to
the fuel nozzles in
each combustor. If adjusting the fuel splits 108 does not resolve the tuning
issue and place the
operational parameters data back into conformance with the operational
standards, a further
adjustment to an operational control element is performed. In the example
shown, the next
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incremental adjustment may be a change of the fuel temperature set point. In
this adjustment
step, the tuning controller 10 sends a modified fuel inlet temperature signal
to the DCS 20, which
is directed to the fuel heating unit 60.
[0063] After the incremental steps are taken in step 108, a check at step
110, is made to see if
modification of the combustor fuel splits and/or fuel inlet temperature
resolved the tuning issue.
If further tuning corrections are needed, the tuning controller 10 will then
alter the overall
fuel/air ratio 112. This approach makes changes to the turbine thermal cycle
utilizing fixed
incremental changes over pre-determined amounts of time. This step of
modifying the fuel/air
ration 112 is intended to adjust the exhaust temperature (up or down) by
adjusting the air to fuel
ratio in accordance with predetermined, standard control curves for the
turbine operation, which
are maintained within the memory of the tuning controller 10.
[0064] If changes made to the turbine's overall fuel/air ratio do not
resolve the tuning issue
114, the tuning controller 10 will adjust the fuel blend ratio 116. Typically,
if an alarm condition
requires tuning, the amount of pipeline quality fuel will be increased
incrementally in relation to
the amount of non-pipeline quality fuel.
[0065] Additionally, if there is sufficient margin 118 in the turbine's key
operational
parameters and the Optimum Fuel Blend Ratio toggle switch 19 is "On", the
tuning controller 10
will send a command to the fuel blend ratio controller 70 to increase the
ratio of non-pipeline
quality fuel to pipeline quality fuel. The margin 118 for determining whether
a fuel blend
adjustment may be made, or is necessary, is determined based on the other
operational
parameters of the system, such as NOx, dynamics or power. In a preferred
embodiment, the
margin 118 represents a buffer or second set of limits within the operational
envelope that is
determined for other operational parameters of the system, such as NOx,
dynamics or power.
Thus, if the operating state of the system is within this second set of
limits, the fuel blend ratio
controller 70 will adjust the fuel blend ratio 116 to increase the amount of
non-pipeline quality
fuel. Conversely, if the system is outside of allowable limits, the ratio of
pipeline quality fuel
will be increased. In a situation where non-pipeline quality fuel is being fed
to the turbine and
tuning event occurs due to an alarm such as from NOx, high or low dynamics or
power, the ratio
of non-pipeline quality fuel may be lowered, or other parameters may be
adjusted, depending on
the type of alarm and user's operational preferences.
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100661 In the present disclosure, the normal mode of communication provides
tuning
changes utilizing control signals intended for a given control element that
are directed by the
tuning controller 10 that are fed to the turbine controller 30 fuel
temperature controller 60, and /
or fuel blend ratio controller 70 through the DCS 20. However, the control
signals can also be
communicated directly to the turbine controller 30, etc. without use of the
DCS 20. These
adjustments are implemented directly within the various controller means
within the system or
through the turbine controller 30. When the operational data is returned to
the desired
operational standards, the tuning settings are held in place by the tuning
controller 10 pending an
alarm resulting from non-conforming data received from the sensor means 40,
50, 60.
[0067] The incremental adjustments sent from the tuning controller 10 to
the turbine
controller 30 or the associated controller means (30, 60, 70) are preferably
fixed in magnitude.
Thus, the adjustments are not recalculated with new data or optimized to a
modeled value or
target. The adjustments are part of an "open loop," which is bounded by the
preselected
operational boundaries. Once started, the adjustments move incrementally to
the preset
maximum or maximum within a specified range, unless an interim adjustment
places the
operation data into conformance with the operational standards. Under most
circumstances,
when the full incremental range of available adjustments for one operational
control element is
completed, the tuning controller 10 moves on to the next operational control
element, which is
defined by the preset operational priorities. The logic of the tuning
controller 10 drives the
adjustment of operational control elements on a step-by-step basis, where the
incremental steps
of adjustment for each control element are stored within the memory of the
tuning controller 10.
[0068] The tuning controller 10 preferably addresses one operational
control element at a
time. For example, the dominant tuning criteria 106 dictates the first
adjustment to be made.
The order of which operational control elements are to be adjusted is not
fixed and will vary
based on operating parameters and inputs such as the dominant tuning criteria
106. In the
preferred example discussed above, the fuel distribution/split control element
is first adjusted in
step 108. As indicated in Fig. 4, during this step, the fuel split of fuel
circuit 1 ¨ the center
nozzle in the combustor ¨ is first addressed, followed by the split for fuel
circuit 2 ¨ the outer
nozzles in the combustor. This system can also be applicable to other
combustion turbine
configurations that do not include a center nozzle in a can annular
configuration, but do contain a
number of fuel circuits. Similarly, this system can be applied to an annular
combustion
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configuration with more than one fuel circuit or a liquid fuel system with a
single fuel circuit and
the ability to vary the fuel to air ratio.
[0069] It should be noted that the application of fuel circuits 1 and 2 is
general in nature and
can be applied to the specific hardware configuration within any particular
combustion system.
Therefore, this tuning approach is applicable to any combustion system with
multiple fuel
sources, regardless if it has only one fuel split, two fuel splits, more than
two fuel splits, or no
fuel splits. If the combustion system has only one useful fuel split, then
this second tuning step
or adjusting fuel circuit 2 is left within the tuning algorithm; but,
abandoned in-place. If the
combustion system has more than 2 fuel splits, then the 2 most effective fuel
split "knobs" are
utilized. If the combustion system has no fuel circuits but does have multiple
fuel sources where
the amount of fuel from each source can be controlled
10070] The fuel gas inlet temperature adjustment generally follows the fuel
split adjustments
when needed. Within each step, there is an incremental adjustment, followed by
a time lag to
permit the adjusted turbine operation to stabilize. After the time lag, if the
current operational
data analyzed by the tuning controller 10 indicates that turbine operation
still remains outside of
the operational standards, the next incremental adjustment within the step is
made. This pattern
repeats for each step. Under most circumstances, only when one adjustment step
is completed
does the tuning controller move onto the next operational control elements.
[0071] The inlet temperature adjustment generally follows the fuel split
adjustments when
needed. Within each step, there is an incremental adjustment, followed by a
time lag to permit
the adjusted turbine operation to stabilize. After the time lag, if the
current operational data
analyzed by the tuning controller 10 indicates that turbine operation still
remains outside of the
operational standards, the next incremental adjustment is made. This pattern
repeats for each
step. Under most circumstances, only when one adjustment step is completed
does the tuning
controller move onto the next operational control element. As mentioned above,
there exists an
over-riding loop whereby the tuning controller 10 will directly increase the
non-pipeline quality
fuel blend ratio (through the fuel blend ratio controller 70) if key turbine
operational
characteristics possess ample operational margin (against alarm conditions)
118. The control
methodology of this over-riding control loop is identical to that mentioned
above for fuel splits
and turbine fuel air ratio ¨ a change is made in a pre-defined direction, a
pre-defined amount, in a
pre-defined amount of time. Analogously, a liquid fueled machine can adjust
the ratio of two
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fuel streams with differing thermophysical properties or optimize for one fuel
source or a lower
or higher fuel source for a prolonged operating period.
[0072] The tuning controller 10 preferably controls combustion operation to
maintain proper
tuning in variable conditions of ambient temperature, humidity and pressure,
all of which vary
over time and have a significant effect on turbine operation. The tuning
controller 10 may also
maintain the tuning of the turbine during variation in fuel composition.
Variation in fuel
composition may cause a change in the heat release, which can lead to
unacceptable emissions,
unstable combustion, or even blow out. In this event, the tuning controller 10
will adjust fuel
composition entering the turbine indirectly through changes in the fuel blend
ratio 116. The
tuning controller may also serve to supplement this adjustment in fuel
composition to tune
operational control elements (such as fuel distribution, fuel inlet
temperature, and/or turbine
fuel/air ratio) to address the effects on combustion output and discharge. In
each case, if the
Optimum Fuel Blend Ratio switch 19 is "On" and the variation of conditions
leads the operation
of the turbine to be within the operational limits, the amount of non-pipeline
quality fuel will be
increased in relation to the amount of pipeline quality fuel. Conversely, if
variations in
operational conditions leads to the turbine operating outside of the preset
limits, or an alarm
condition occurring, the ratio of pipeline quality fuel will be increased.
[0073] In other tuning scenarios, an alternate order for the adjustments is
contemplated. For
example, if the dominant operational priority is optimum NOx emissions (such
as selected using
switch 14 of Fig. 2), the fuel temperature adjustment may be skipped, going
directly to the
operational control curves to adjust fuel/air ratio. If, however, dynamics is
the operational
priority (and the optimum NOx emission switch 14 is "Off'), the incremental
fuel temperature
adjustment may be performed before going to the operational control curves.
Alternatively, the
step of making adjustments to control elements in accordance with the
operational fuel air ratio
control curves may be turned off completely, based on a user's priorities.
[0074] Fig. 7 provides a schematic that details the framework for
determining the dominant
tuning concern 106, as included in Fig. 4. Future steps will be described
below with respect to
Fig. 8. First, relevant emissions parameters 120 and combustor dynamics 122
are received by
the tuning controller 10 from the CEMS 40 and CDMS 50, as detailed above. The
relevant
emissions parameters 120 and combustor dynamics 122 are then compared to
allowable tuning
limits 124 that are also provided to the tuning controller 10. The allowable
tuning limits are in
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the form of preset ranges that may be adjusted using the tuning interface 12
of Fig. 3 and
determined according to the logic set forth below with respect to Figs. 6 and
7. The output of
this comparison is a series of "True" alarms 126 of various tuning concerns,
where an alarm
condition is indicated if the sensed operational data 120, 122 is above or
below a given alarm
range set forth in the tuning limits 124. In the event that Optimum Fuel Blend
Ratio switch 19 is
"On," the allowable tuning limits for emissions, dynamics and power will also
be provided as
part of step 124. Likewise, a "True" condition will exist if sufficient
operating margin exists for
increasing the fuel blend ratio, as shown in step 118. The fuel blend ratio
will be adjusted in step
116 as part of the tuning process shown in Fig. 4.
[0075] Alarm conditions may have more than one level or tier, For example,
there may be
varying degrees of severity of an alarm, such as: high "H"; high-high "HH";
high-high-high
"1 HiH" and low "L"; low-low "L"; low-low-low "LLL". The "True" logical alarms
126 are
subsequently ranked according to their level of importance (e.g. high ¨ high
"HH" alarms are
more important than high "H" alarms, etc.) in step 130. If more than one
tuning concern shares
the same level, the tuning concerns will then be ranked according to the user
preferences as set
forth below with respect to Fig. 10. If only one "True" alarm emerges, this
will be selected and
used as the dominant tuning concern 106 to initiate the tuning process as set
forth in Fig. 2.
However, the results of the process of Fig. 7, namely the ranked "True" alarms
130, will be
processed through user determined criteria, as shown in Fig. 8, before a
dominant tuning concern
106 is confirmed.
[0076] In Fig. 8, a flow chart is provided to explain how the allowable
tuning limits 124 are
determined. Once determined, the tuning limits 124 are compared to the
operational data 120,
122 as set forth above and shown in Fig. 7. First, the User Interface Toggle
Switches 14, 16, 18,
19 corresponding to those in the interface display 12 of Fig. 5, are compared
against each other,
utilizing an internal hierarchy to allow passage of the alarm constraints
relative to the most
significant toggle switch. Thus, depending on which switches are in the "On"
position, different
tuning limits will be included in the allowable tuning limits 124. Each of
Optimum NOx,
Optimum Power and Optimum Dynamics has a collection of preset limits (denoted
by the
numerals 134, 136 and 138 in Fig. 8), depending on whether the corresponding
toggle switch 14,
16, 18, 19 is in the "On" of "Off' position. There is also an internal set of
default limits 140 to
be used when none of the toggle switches are in the "On" position.
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[0077] The internal hierarchy will determine which tuning limits shall take
precedence in the
event that competing toggle switches 14, 16 18, or 19 are in the "On"
position. In the present
example, the hierarchy ranks Optimum NOx above Optimum Power. Optimum Dynamics
may
be selected at any time and will simply alter the tuning limits of the other
selections given, such
as is shown in Fig. 4. If Optimum NOx 14 and Optimum Power 16 are both in the
"On"
position, the tuning limits for Optimum NOx 134 will be used. Additionally,
the tuning limits
for Optimum Dynamics 138 are utilized if this toggle switch 18 is activated.
If no User Interface
Toggle Switches 14, 16, 18, 19 are active, default tuning limits 140 are
provided as the allowable
tuning limits 124. All of the tuning limits 134, 136, 138 and 140 that may be
used to construct
the allowable tuning limits for the tuning controller 10 may be developed by
the end user and
programmers and are then preferably hard coded into the tuning controller 10
for a given
application. The methodology outlined in Fig. 7 is meant to provide an
exemplary framework
for incorporation of a number of different User Interface Toggle Switches,
such as those options
set forth above with respect to Fig. 5, whereby only a subset are specifically
outlined in this
disclosure.
[0078] The allowable tuning limits for determining whether an increase in
fuel blend ratio is
allowable will be based on the selected tuning limits based on other
operational parameters of the
system, such as NOx, dynamics or power. Thus, depending on what the limits are
for the other
parameters, fuel blend tuning limits 160 will be established and compared to
the operating
conditions of the turbine to determine if a fuel blend ratio adjustment is
called for.
[0079] Fig. 9 shows a specific example of the flow chart of Fig. 7 is given
for the
determination of a subset of the system's allowable tuning limits, In this
example, the tuning
limits for High NOx, High High NOx, High Class 1 SP's, High Class 2 &P's will
be determined
based on preset tuning limits and the user's preferences. The various
exemplary tuning limits are
provided for Optimum NOx 134, Optimum Power 136, Optimum Dynamics 138, and No
Optimal Settings 140 are given corresponding numerical values (shown
respectively in blocks
152, 154, 156 and 158). The corresponding numerical values given for each
criterion vary, such
that the allowable limits 124 will be different depending on which toggle
switches 14, 16 18, or
19 are selected. By way of example, the Optimum NOx 134, 152 and Optimum Power
136, 154
give limits for NOx, but also provide limits for Dynamics that are to be used
in the event that
Optimum Dynamics 138, 156 is not selected. However, in the event that the
Optimum Dynamics
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toggle 18 is selected, the Class 1 6P's and Class 2 6P's values provided,
therefore 156 shall be
used instead of the values listed with respect to Optimum NOx 134, 152 and
Optimum Power
136, 154.
[0080] As described above with respect to Fig. 8, the fuel blend ratio
limits 160 are
determined based on the other operational parameters of the system, such as
NOx, dynamics or
power. Here, the specific limits for determining whether an increase in the
ratio of non-pipeline
quality fuel are set forth in block 162. The limits for High and Low NOx, are
based on the other
limits set forth as the result of the optimum NOx and Dynamics switches 14, 16
being "On."
Thus the fuel blend limits shown at 162 are within the operational envelope
determined by the
other operational parameters of the system.
[0081] In this particular example, the toggle switches for Optimum NOx 14
and Optimum
Dynamics 18 are selected, with the switch for Optimum Power 16 left in the
"Off" position.
Thus, the values from Optimum NOx for High NOx and High High NOx 152 are
provided.
Also, because Optimum Dynamics 18 is also selected, the Dynamics values for
High Class 1
6P's and High Class 2 6P's 138, 156 replace those 6P's values provided with
respect to Optimum
NOx 134, 152. As a result, the allowable tuning limits 124 are provided as
shown in block 164.
These allowable tuning limits 124 correspond to those used in Fig. 4, as
described above, to
determine whether information from the CEMS 40 and CDMS 50 is in an alarm
state or
operating normally.
[0082] Fig. 10, shows a schematic for the process of incorporating a user's
priorities and the
"True" alarm conditions received for determining the dominant tuning concern
106. It is this
tuning concern 106 which dictates all turbine operational changes the turbine
controller 10
performs, as shown in Fig. 4.
[0083] First, a determination is made of all potential dominant tuning
issues 142. These
include, but are not limited to: combustor blowout, CO emissions, NOx
emissions, Class 1
combustor dynamics (Class 1 613's), and Class 2 combustor dynamics (Class 2
6P's). The list of
potential dominant tuning issues 142 is determined by the user and programmer
and may be
based on a number of factors Or operational criteria. By way of example, Class
1 and Class 2
combustor dynamics 6P's refer to combustion dynamics occurring over specific
ranges of
acoustic frequencies, whereby the range of frequencies is different between
Classes 1 and 2.
Indeed, many combustion systems can possess different acoustic resonant
frequencies
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corresponding to Class 1 and Class 2, and variations in these 2 dynamics
classes may be
mitigated utilizing different turbine operational parameter changes for each
different turbine and
/ or combustor arrangement. It should also be noted that certain combustion
systems may have
none, 1, 2, or greater than 2 different "classes" (frequency ranges) of
combustor dynamics which
can be tuned. This disclosure utilizes a system whereby 2 different combustor
dynamics classes
are mentioned. However, it is fully intended that this disclosure can be
broadly applied to any
number of distinct dynamics frequency classes (from 0 to greater than 2).
[0084] After determination of the potential dominant tuning issues 142,
these issues are
ranked in order of significance 144 according to the end user's needs as well
as the detrimental
effects that each tuning concern can have on the environment and / or turbine
performance. The
relative importance of each potential dominant tuning concern can be different
with each end
user, and for each combustor arrangement. For example, some combustion systems
will
demonstrate an extreme sensitivity to combustor dynamics, such that normal
daily operational
parameter variations can cause a normally benign dynamics tuning concern to
become
catastrophic in a very short amount of time, In this case, one or both of the
dominant dynamics
tuning concerns (Class 1 and Class 2) may be elevated to Priority I (Most
Important). By way of
example in Fig. 7, combustor blowout is listed as the most important Dominant
Tuning Concern
144. This ranking is used to determine the dominant tuning concern in the
event that there are
multiple alarms with equal levels of severity. This ranking of Dominant Tuning
Concerns 144,
from most to least important, provides the overall framework where the
specific Boolean Logic
Hierarchy 148 is created. For example, assuming Class 1 and Class 2 8P's
combustor dynamics
obey monotonic behavior relative to perturbations in system operational
parameters, a High-High
"HH" Class 2 SP's alarm may be more significant than High "H" Class 1 oP's
alarm.
Additionally, in the example given in Fig. 8 for the Boolean Logic Hierarchy
148, High "H"
NOx emissions is more significant than High "H" Class 2 dynamics. This means
that if both
High "H" NOx and High "H" Class 2 dynamics are both "in alarm" (Logic = True),
in the
absence of other alarms being "True", the autotuning system will tune for High
"H" NOx
because it is the dominant tuning concern. Finally, it can be seen that
Blowout is ranked above
NOx Emissions and both are ranked above Class 1 OP's. Thus, if there were high
"H" alarms
returned for all three categories, Blowout would be the dominant tuning
concern, followed by
NOx Emissions and then Class 1 OP's. This Boolean Logic Hierarchy 148 will be
what is
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compared to the "True" alarms 130 returned by comparing the allowable tuning
limits 124 to the
operational data 120, 122 as set forth above with respect to Fig. 5.
[0085] All "True" tuning alarms 130 are provided as ranked by severity
(e.g. HHH above
HH, etc.). The "True" tuning alarms 130 are then compared with the hard-coded
Boolean Logic
Hierarchy 148, in step 150 to determine which tuning will become the "True"
Dominant Tuning
Concern 106. This one "True" Dominant Tuning Concern 106 is now passed into
the remainder
of the autotuning algorithm, as detailed in Fig. 2, as the Dominant Tuning
Concern 106 to be
mitigated by operational changes.
[0086] Figs. 11-15 provide exemplary graphical representations of the
autotuning system
interface depicting how the Boolean Logic Hierarchy works in practice. Fig. 11
shows the
alarms returned in connection with the example set forth above with respect to
Fig. 10. Namely,
alarms are returned for Class 2 OP's at the levels of H 162, HH 164 and 141111
166. In addition,
alarms for NOx 168 and Class 1 OP's 170 are returned at the H level. Since
more extreme levels
trump conflicts of different alarms at the same level, the HHH Class 2 OP's is
the priority and
therefore the dominant tuning concern 172.
[0087] Figs. 12-14 show various further examples of the dominant tuning
concern for
different "True" alarm levels under the user defined hierarchy 144 of Fig. 10.
Fig. 12 shows a
NOx alarm at the HH level returned, with no other alarms of this severity.
Thus, high NOx is the
dominant tuning concern. Fig. 13 shows a Class 1 OP's at an H level as the
only alarm condition,
thus making Class 1 OP's as the dominant tuning concern. Finally, Fig. 14
shows that Class 2
OP's and Blowout both return alarms at the H level. Referring to the user
ranking of dominant
tuning issues 144 in Fig. 8, Blowout is ranked as a priority above Class 2
OP's and thus, although
the severity of the alarms is equal, Blowout becomes the dominant tuning
concern.
[0088] Fig. 15 shows an operational example of when an increase of the fuel
blend ratio may
be called for. In this case, there are no tuning limit alarms, such as those
shown in Figs. 11-14.
Thus, the system is operating within the operational envelope. Also, the
system is operating
within the operational limits where the amount of non-pipeline quality fuel
may be increased,
such as those shown in block 162 of Fig. 9. In such a case, the system will
indicate that in
increase in fuel blend ratio is called for.
100891 In Figs. 16 ¨19, there is shown various examples of the operational
results of a tuning
operation of a tuning controller of the present disclosure based on
operational data from a
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running turbine system. In Fig. 16, the dominant tuning concern is high Class
2 SP's, and a
change in the combustor fuel split El is made in reaction to a high Class 2
613's alarm generated
when the combustor dynamics moves outside of the set operational priorities
for optimum
dynamics. The actual combustor dynamics data received by the turbine
controller 10 from, for
example, the CDMS 50 is designated as 200 in the graph. The moving average for
the
combustor dynamics is identified in the graph as 202. When the combustor
dynamics exceed the
dynamics alarm limit value 204 for a set period of time TA an alarm goes off
within the tuning
controller. This alarm causes the first event El and a resulting incremental
adjustment in the
combustor fuel split tuning parameter 206. As illustrated, the incremental
increase in the fuel
split causes a corresponding drop in the combustor dynamics 200, with the
average combustor
dynamics 202 dropping below the dynamics alarm limit 204. As time continues,
the tuning is
held by the tuning controller and the average combustor dynamics 202 maintains
its operational
position below the dynamics limit 204. Thus, no further adjustments necessary
or alarms issued.
[0090] In Fig. 17, the tuning criteria is NOx emissions. As NOx emissions
data 210 is
received from the tuning controller, an alarm is generated after the passage
of time TA. The
alarm is caused by the NOx emissions 210 exceeding the operational standard or
tuning limit
212. The alarm activates a first event El resulting in an incremental increase
in the fuel split
214. After a period of time TB from the first event El, the NOx alarm is still
activated due to the
NOx emissions 210 exceeding the preset tuning limit 212. This continued alarm
after time TB
causes a second event E2 and a second incremental increase in the fuel split
value 214. This
second increase is equal in magnitude to the first incremental increase. The
second event E2
causes the NOx emissions level 210 to drop below the preset limit 212 within
the review time
period and halts the alarm. As the NOx emissions 210 remains below the limit
212, the fuel split
214 tuning is held and the operation of the turbine continues with the defined
operational
parameters.
[0091] In Fig. 18, the tuning criteria is again NOx emissions, with the
alarm created by a low
reading received by tuning controller. As shown, the NOx tuning limit 220 is
defined. Upon
passage of the set time period TA from receiving NOx level data 222, the alarm
is generated and
a first event El occurs. At the first event El, the fuel split level 224 is
incrementally adjusted
downward. After a set passage of time TB from event El additional NOx
emissions data 222 is
received and compared to the preset alarm level 220. Because the NOx is still
below the alarm
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level 220, a second event E2 occurs resulting in a further incremental
reduction in the fuel split
value 224. A further passage of time TC from event E2 occurs and additional
data is received.
Again, the NOx data 212 is low, maintaining the alarm and resulting in a
further event E3. At
event E3, the fuel split value 224 is again reduced by the same incremental
amount. This third
incremental adjustment results in the NOx emissions 222 rising above the
preset limit 220 and
results in removal of the alarm. The fuel split 224 tuning value set after
event E3 is held in place
by the tuning controller 10.
[0092] In Fig, 19, the NOx emissions data 230 received by the tuning
controller 10 is again
tracking along the lower emissions limit 232. At the first tuning event El,
the fuel split value 234
is incrementally dropped to result in a corresponding increase in the NOx
emissions 230 over the
lower limit 232. After this first incremental adjustment, the NOx emissions
for a period of time
holds above the limit 232 and then begins to again fall. At the second tuning
event E2, the fuel
split value 234 is again adjusted by the designated fixed incremental value.
This second
adjustment then places the fuel split value 234 at its defined minimum within
the preset range of
allowable values (determined as a hard coded limit within the tuning
controller 10). Because this
limit is reached, the tuning operation moves to the next operational
parameter, which is normally
the second fuel circuit adjustment. In the example provided, this second
circuit value (not
shown) is already at its set maximum/minimum and is therefore not adjusted.
Thus, the tuning
operation moves on to the next operational parameter, load control curves 236.
As shown, at
event E2 an incremental adjustment is made in the load control curve value
236. The increase in
the load control curve value 236 results in a corresponding increase in the
NOx emission 230 to a
value above the minimum 232 and removes the alarm. Upon removal of the alarm,
the tuning
settings are held and no further adjustments are made. The tuning controller
10 then proceeds to
receive data from the sensor means, through the DCS, and continues to make
comparisons with
the set operational standards (including the minimum NOx emissions limit EL).
[0093] Figs. 20 and 21 are typical schematic representations of the
operation of the tuning
controller within contemplated disclosure. The operation of the turbine is
defined by the
emission output of the turbine, both NOx and CO, turbine dynamics and flame
stability. In Fig.
19, a tuned system is defined by a preferred operating envelope in the center
of the operational
diamond. This preferred operational envelope is typically manually set based
on a prior start-up
or operation of the turbine system. However, weather changes, both hot and
cold, and
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mechanical changes within the turbine system cause a drift within the
operational diamond.
Hence a tuning is desired so as to maintain the turbine operation within the
preferred range.
[0094] Fig. 20 also provides an example image of the allowable operating
space, 280 where
an increase in the amount of the non-pipeline quality fuel is permissible. As
described above, this
operating space is within the range defined by the allowable tuning limits.
[0095] In Fig. 21, a defined buffer / margin 132 is set within the
operational diamond to
serve as a warning for a drift of the turbine operation outside of the
preferred operational
envelope. Once one of the sensed operational values reaches the defined buffer
line or limit, an
alarm is generated, causing a tuning event. Based on the direction of the
drift, the tuning
controller creates a preset reaction to meet the specifics of the tuning need.
This preset reaction
is a defined incremental shift in an operational parameter of the turbine as a
means for moving
the turbine operational envelope back into the desired range, and away from
the buffer limit.
Also shown on Figs. 20 and 21 are representations of the operating spaces
employed by selecting
the Optimum NOx 14, Optimum Power 16, and Optimum Combustor Dynamics 18 Toggle
Switches of the User Interface Display 12 of Fig. 5 within the overall turbine
combustor
operating envelope. It should be noted that Fig. 20 does not show a pictorial
representation of
the Optimum Fuel Blend Ratio 19 optimization mode. This operational mode
overlays "on top"
of the entire combustion operating envelope with no clear bias toward any edge
of operation, and
as such is not shown. It should be noted that each parameter may have more
than one alarm, such
as high "H"; high-high "HH" and high-high-high "HHH." These alarms may be
sequentially
located around the diamond shown to alert operators of how close the turbine
operation is to the
outside of desired operational limits.
[0096] The present disclosure has been described and illustrated with
respect to a number of
exemplary embodiments thereof. It should be understood by those skilled in the
art from the
foregoing that various other changes, omissions and additions may be made
therein, without
departing from the spirit and scope of the present disclosure, with the scope
of the present
disclosure being described by the foregoing claims.
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