U.S. patent application number 12/170513 was filed with the patent office on 2009-02-05 for method for operating a firing plant.
Invention is credited to Mauricio GARAY, Gianfranco GUIDATI, Stanka KOKANOVIC, Stephan TORCHALLA.
Application Number | 20090037029 12/170513 |
Document ID | / |
Family ID | 36144600 |
Filed Date | 2009-02-05 |
United States Patent
Application |
20090037029 |
Kind Code |
A1 |
GARAY; Mauricio ; et
al. |
February 5, 2009 |
METHOD FOR OPERATING A FIRING PLANT
Abstract
A method for operating a firing plant with at least one
combustion chamber and with at least one burner for producing hot
gas, especially a gas turbine, preferably of a power generating
plant, includes an operating characteristic for operating the
combustion chamber close to the lean extinction limit defined in
the form of a burner group staging ratio (BGV.sub.Rich). The
pressure pulsations (Puls.sub.Actual) which are measured in the
combustion chamber are processed by a filter device (2) and
converted into corresponding signals (Puls.sub.Actual,Filter(t)).
An exceeding/falling short of at least one pulsation limiting value
(Puls.sub.Limit) is monitored by a monitoring device (3) and adapts
a pulsation reference value (Puls.sub.Ref) in dependence upon the
monitoring. The processed pressure pulsations
(Puls.sub.Actual,Filter(t)) are then compared with the adapted
pulsation reference value (Puls.sub.Ref,adapt), and, from this, a
correction value .DELTA.BGV is determined, by which the burner
group staging ratio (BGV.sub.Rich) is corrected, and as a result
operation of the firing plant close to the lean extinction limit is
realized.
Inventors: |
GARAY; Mauricio; (Las Heras
Mendoza, AR) ; GUIDATI; Gianfranco; (Zuerich, CH)
; KOKANOVIC; Stanka; (Baden, CH) ; TORCHALLA;
Stephan; (Kastl, DE) |
Correspondence
Address: |
CERMAK KENEALY & VAIDYA LLP
515 E. BRADDOCK RD, SUITE B
ALEXANDRIA
VA
22314
US
|
Family ID: |
36144600 |
Appl. No.: |
12/170513 |
Filed: |
July 10, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
PCT/EP2006/068662 |
Nov 20, 2006 |
|
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|
12170513 |
|
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Current U.S.
Class: |
700/287 ; 60/772;
60/776; 700/41 |
Current CPC
Class: |
F23N 2223/48 20200101;
F23N 2237/02 20200101; F23N 1/002 20130101; F23R 3/34 20130101;
F02C 9/26 20130101; F23N 5/16 20130101; F23C 2900/06042
20130101 |
Class at
Publication: |
700/287 ; 60/772;
60/776; 700/41 |
International
Class: |
F02C 9/28 20060101
F02C009/28; G05B 11/01 20060101 G05B011/01; G05D 17/02 20060101
G05D017/02 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 11, 2006 |
CH |
00049/06 |
Claims
1. A method for operating a firing plant having at least one
combustion chamber and at least one burner, the firing plant for
producing hot gas, the method comprising: defining an operating
characteristic for operating the combustion chamber close to the
lean extinction limit, in the form of a burner group staging ratio
(BGV.sub.Rich); measuring, in the combustion chamber, pressure
pulsations (Puls.sub.Actual(t)); converting said measured pressure
pulsations (Puls.sub.Actual(t)) into corresponding signals;
monitoring exceeding or falling short of at least one pulsation
limiting value (Puls.sub.Limit); adapting a pulsation reference
value (Puls.sub.Ref) in dependence upon said monitoring to form an
adapted pulsation reference value (Puls.sub.Ref,adapt); processing
said corresponding signals by a filter device to produce processed
pressure pulsations (Puls.sub.Actual,Filter(t)); comparing the
processed pressure pulsations (Puls.sub.Actual,Filter(t)) to the
adapted pulsation reference value (Puls.sub.Ref,adapt); determining
a correction value (.DELTA.BGV) from said comparing; and correcting
the burner group staging ratio (BGV.sub.Rich) based on said
correction value (.DELTA.BGV).
2. The method as claimed in claim 1, wherein said determining the
correction value (.DELTA.BGV) further comprises determining in
dependence upon at least one amplification factor (K.sub.PI), upon
at least one time constant (T.sub.PI), or upon both; or the
pulsation reference value (Puls.sub.Ref), or the amplification
factor (K.sub.PI), or the time constant (T.sub.PI), or combinations
thereof, is dependent upon load; or different amplification factors
(K.sub.PI) and/or time constants (T.sub.PI) are taken into
consideration for constant load cases and for transient load cases;
or combinations thereof.
3. The method as claimed in claim 2, further comprising:
determining different amplification factors (K.sub.PI), or time
constants (T.sub.PI), or both, for constant load cases and for
transient load cases.
4. The method as claimed in claim 1, further comprising:
establishing a load-dependent pulsation reference value
(Puls.sub.Ref); and decreasing or increasing, by a predetermined
quantity, the load-dependent pulsation reference value
(Puls.sub.Ref) when a predetermined number of pulsation values lie
above or below the predetermined pulsation limiting value
(Puls.sub.Limit) within a predefined time period.
5. The method as claimed in claim 1, comprising performing said
method in a closed-loop control circuit.
6. The method as claimed in claim 1, wherein the firing plant
comprises a gas turbine.
7. The method as claimed in claim 6, wherein the gas turbine
comprises a turbine of a power generating plant.
8. A firing plant comprising: at least one combustion chamber; at
least one burner for producing hot gas; wherein a burner group
staging ratio (BGV.sub.Rich) is defined for operating the
combustion chamber close to the lean extinction limit; a measuring
device configured and arranged to measure pressure pulsations
(Puls.sub.Actual(t)) in the combustion chamber; a monitoring device
configured and arranged to monitor the level of at least one
pulsation limiting value (Puls.sub.Limit), to adapt a pulsation
reference value (Puls.sub.Ref) in dependence upon the level to form
an adapted pulsation reference value (Puls.sub.Ref,adapt), and to
generate at least one signal corresponding to the measured pressure
pulsations (Puls.sub.Ref(t)); a filter device configured and
arranged to process the at least one signal corresponding to the
measured pressure pulsations (Puls.sub.Ref(t)) and generate
processed pressure pulsations (Puls.sub.Actual,Filter(t)); and a
control unit configured and arranged to compare the processed
pressure pulsations (Puls.sub.Actual,Filter(t)) with the adapted
pulsation reference value (Puls.sub.Ref,adapt) and determine a
correction value (.DELTA.BGV) by which the burner group staging
ratio (BGV.sub.Rich) can be corrected.
9. The device as claimed in claim 8, wherein the filter device
comprises a first order filter.
10. The device as claimed in claim 8, wherein the monitoring device
is further configured and arranged change the pulsation reference
value (Puls.sub.Ref) by a predetermined quantity when, within a
defined time period, a predetermined number of pulsation values are
outside the at least one pulsation limiting value
(Puls.sub.Limit).
11. The device as claimed in claim 8, wherein the control unit
comprises a proportional/integral controller, a proportional
controller, or an integral controller.
12. A gas turbine comprising a firing plant as claimed in claim
8.
13. A power generating plant comprising a gas turbine according to
claim 12.
Description
[0001] This application is a Continuation of, and claims priority
under 35 U.S.C. .sctn. 120 to, International App. No.
PCT/EP2006/068662, filed 20 Nov. 2006, and claims priority
therethrough under 35 U.S.C. .sctn..sctn. 119, 365 to Swiss App.
No. 00049/06, filed 11 Jan. 2006, the entireties of which are
incorporated by reference herein.
BACKGROUND
[0002] 1. Field of Endeavor
[0003] The present invention relates to a method for operating a
firing plant with at least one combustion chamber and with at least
one burner for producing hot gas, especially a gas turbine,
preferably in a power generating plant. The invention also relates
to a firing plant with at least one combustion chamber and at least
one burner for producing hot gas.
[0004] 2. Brief Description of the Related Art
[0005] A firing plant, for example a gas turbine, customarily has
at least one combustion chamber with at least one burner.
Furthermore, a fuel supply system is always provided, by which the
burners are supplied with fuel. With regard to regulations which
are becoming ever stricter concerning limiting values which are to
be observed for pollutant emissions, it is sought to operate the
burners as close as possible to the lean extinction limit. As a
result of such a lean operation, especially the creation of harmful
NO.sub.x emissions can be reduced.
[0006] The influencing parameters which determine the extinction
limit vary in this case during operation of a gas turbine. Such
influencing parameters, for example, are boundary conditions such
as the ambient temperature, the relative air humidity, the air mass
flow which depends especially upon the operating state of the
upstream compressor, and the composition of the fuel which is
currently used, etc. The burners, with regard to their fuel feed,
are frequently divided into two or more groups so that an influence
can be exerted upon the equivalence ratio of the combustion
process. In this case, the fuel feed to the two or more burner
groups is customarily controlled in dependence upon the
aforementioned factors. Since, however, not all important
parameters, and especially not all changes to each time point, can
be adequately taken into consideration, a predefined fuel staging
ratio or burner group staging ratio is always selected with a
certain safety margin to the lean extinction limit.
[0007] This safety margin is to ensure that even during a change of
the individual boundary conditions, which act differently upon the
stability of the combustion process, a stable operation of the
individual burners is ensured. A stable operating state takes
highest priority, especially in the case of power generating plants
which are used for electric power generation, so that the safety
margin is greater than is absolutely necessary and consequently
higher NO.sub.x emissions are accepted.
SUMMARY
[0008] The present invention starts at this point. One of numerous
aspect of the present invention deals with an operating method of
the aforementioned type, which especially enables stable operation
of the combustion chamber which is as close as possible to the lean
extinction point.
[0009] Another aspect of the present invention includes controlling
the fuel feed to the burners of the combustion chamber in
dependence upon pressure pulsations which occur in the combustion
chamber, wherein the controlling is achieved by a comparison of the
pressure pulsations which occur and are conditioned in the
combustion chamber with predetermined and adapted pulsation
reference values. One exemplary embodiment uses the knowledge that
the pressure pulsations increase as the combustion process
approaches the lean extinction limit. First of all, therefore, an
operating characteristic for operating the combustion chamber close
to the lean extinction limit is defined or determined in the form
of a burner group staging ratio, and at the same time the pressure
pulsations which occur in the combustion chamber are measured and
then processed by a filter device. Furthermore, a pulsation
reference value, which is defined in dependence upon load, and also
at least one pulsation limiting value, are defined. A monitoring
device monitors pulsation exceeding/falling short of the pulsation
limiting value, or the pulsation limiting values, in the process
and adapts the pulsation reference value in dependence upon this
monitoring. The pressure pulsations which are measured and
processed in the combustion chamber are then compared with the
adapted pulsation reference value and, as a result, a correction
value is determined by which the operating characteristic which was
defined at the beginning, i.e., the fuel feed, is corrected.
[0010] The filter device in this case has the task of reducing
noise of the recorded pressure pulsation signal, as a result of
which the signal quality can be significantly increased. Such
improved signal quality has a positive effect upon the active
control process of the operating method according to the invention.
In this case the filter device can especially be designed so that
it amplifies relevant signal contents, whereas it attenuates or
eliminates disturbing signal contents. The increasing of the signal
quality in this case can be achieved by use of an amplification
factor K.sub.Filter and also of a time constant T.sub.Filter.
[0011] The method according to an embodiment exemplifying
principles of the invention has a closed-loop control circuit in
which the pulsation reference value is dynamically adapted. By the
method, therefore, the combustion chamber can be operated safely
and yet very close to the lean extinction limit, as a result of
which the NO.sub.x emissions can be significantly lowered. In this
case, a method according to the invention can fall back on the fact
that a modern combustion chamber is always equipped with a sensor
system for monitoring the pressure pulsations so that this sensor
system can be utilized and consequently no additional costs ensue
for instrumentation or realizing a method according to the
invention with regard to recording the pressure pulsations.
[0012] According to an especially advantageous exemplary
embodiment, a load-dependent pulsation reference value is
established which is decreased or increased by a predetermined
quantity provided that, within a defined time period, a determined
number of measured pressure pulsation values lie above/below the at
least one predetermined pressure pulsation limiting value. If,
therefore, a determined number of pulsation values above the
established pulsation limiting value occur within a predefined time
period, then the pulsation reference value is decreased by a
predefined quantity. The adapted pulsation reference values are
used in this case for a predefined time period until a renewed
adaptation of the pulsation reference value is carried out.
[0013] Further features and advantages of operating methods
according to the invention result from the drawings and from the
associated figure description with reference to the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] Preferred exemplary embodiments of the invention are
represented in the drawings and are explained in more detail in the
following description, wherein like designations refer to the same
or similar, or functionally the same, components.
[0015] In the drawing, schematically in each case,
[0016] FIG. 1 shows a much schematized view of a possible sequence
of the operating method according to the invention; and
[0017] FIG. 2 shows a diagram, in which the pattern of pressure
pulsations is plotted.
DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS
[0018] According to FIG. 1, a firing plant, which is not otherwise
shown, with at least one combustion chamber, which is also not
shown, and at least one burner for producing hot gas, has a
measuring device 1 for measuring pressure pulsations
Puls.sub.Actual(t) which converts the pressure pulsations into
preferably electrical signals and transmits the signals to a filter
device 2. The filter device 2 in this case processes the signals
which correspond to the measured pressure pulsations
Puls.sub.Actual(t), wherein preferably relevant signal components
are amplified and irrelevant signal components, such as noise, are
at least reduced. The filter device 2 can have a filter of the
first order for processing the aforementioned signals, which
amplifies the signals coming in from the measuring device 1 with an
amplification factor K.sub.Filter. A time constant T.sub.Filter can
also be established in the processing of the signal, which provides
the pressure pulsation signals Puls.sub.Actual(t) coming in from
the measuring device 1 with a time component. In order to be able
to take into consideration load changes of the firing plant, it is
intended to define two different amplification factors
K.sub.Filter, specifically one for constant load cases and another
for transient load cases. The pressure pulsation signals
Puls.sub.Actual,Filter(t), which are processed by the filter device
2, are transmitted to an evaluating/control unit 4 and in this, or
by this, are compared together with an adapted pulsation reference
value Puls.sub.Ref,adapt.
[0019] The adapted pulsation reference value Puls.sub.Ref,adapt in
this case is dependent upon load and is to bring about the firing
plant being able to be operated as lean as possible, as a result of
which a discharge of NO.sub.x emissions can be reduced.
Determination of the adapted pulsation reference value
Puls.sub.Ref,adapt in this case is carried out as follows:
[0020] First of all, a pulsation reference value Puls.sub.Ref is
defined or established in dependence upon the relative load. The
predefined pulsation reference value Puls.sub.Ref is now monitored
by a monitoring device 3 and at the same time a corrected pulsation
reference value Puls.sub.Ref,adapt is determined in dependence upon
the monitoring by the monitoring device 3. The adaptation of the
pulsation reference value Puls.sub.Ref in this case is carried out
by the monitoring device 3 comparing the measured and preferably
filtered pressure pulsations Puls.sub.Actual(t) or
Puls.sub.Actual,Filter(t) with the predefined pulsation reference
value Puls.sub.Ref, and in the case of exceeding or falling short
of at least one pulsation limiting value Puls.sub.Limit,
correspondingly increases or decreases, and consequently adapts,
the pulsation reference value Puls.sub.Ref. For correction or
adaptation of the established pulsation reference value
Puls.sub.Ref, within a defined time period, a determined number of
pressure pulsation values Puls.sub.Actual(t) must lie above or
below the at least predetermined pulsation limiting value
Puls.sub.Limit accordingly.
[0021] From the two input values, specifically the measured and
filtered pressure pulsations Puls.sub.Actual,Filter on the one hand
and the adapted pulsation reference value Puls.sub.Ref,adapt on the
other hand, the evaluating/control unit 4 now determines a
correction value .DELTA.BGV by which the defined burner group
staging ratio BGV.sub.Rich which was defined at the beginning,
i.e., the operating characteristic, is corrected. The determination
of the correction value .DELTA.BGV in this case is carried out by
comparison of the measured and filtered pressure pulsations
Puls.sub.Actual,Filter with the adapted pulsation reference value
Puls.sub.Ref,adapt. The evaluating/control unit 4 in this case for
example can be formed as a proportional/integral controller, or as
a purely proportional controller, or as a purely integral
controller, and can operate with an amplification factor K.sub.PI
and also with a time constant T.sub.TI which are also defined in
dependence upon the relative load, like the established reference
value Puls.sub.Ref. The original burner group staging ratio
BGV.sub.Rich is corrected by the correction value .DELTA.BGV so
that a burner group staging ratio BGV.sub.New, which is corrected
and better adapted to the new boundary conditions, is achieved.
[0022] According to FIG. 2, the measured pressure pulsations
Puls.sub.Actual are plotted over time t. In this case, an upper
pulsation limiting value Puls.sub.Limit1 and a lower pulsation
limiting value Puls.sub.Limit2 can be established, which, in the
case of exceeding or falling short of, brings about an adaptation
of the pulsation reference value Puls.sub.Ref by the monitoring
device 3, provided that a determined number of pulsation values
Puls.sub.Actual or Puls.sub.Actual,Filter within a defined time
period lie below the pulsation limiting value Puls.sub.Limit2 or
above the upper pulsation limiting value Puls.sub.Limit1. As a
result, a region between Puls.sub.Limit1 and Puls.sub.Limit2 is
therefore defined, in which no adaptation of the pulsation
reference value Puls.sub.Ref is carried out. It is also conceivable
that only one pulsation limiting value Puls.sub.Limit is defined,
which, in the case of exceeding, and also in the case of falling
short of this limiting value, brings about adaptation of the
pulsation reference value Puls.sub.Ref. A region in which no
adaptation of the pulsation reference value Puls.sub.Ref is carried
out is therefore not provided in the case of such an
embodiment.
[0023] A further variant, in which an adaptation of the pulsation
reference value Puls.sub.Ref is carried out, in case within a
shorter time period few pulsation values Puls.sub.Actual lie above
a higher pulsation limiting value, is also conceivable. For
adaptation, therefore, either a certain number of pulsation values
Puls.sub.Actual which, within a certain time interval, exceed the
upper pulsation limiting value Puls.sub.Limit1, are necessary, or a
lower number, in comparison to it, of pulsation values
Puls.sub.Actual which, within a shorter time period lie above a
pulsation limiting value, which is higher than the upper pulsation
limiting value Puls.sub.Limit1, are necessary. The same can apply
in a corresponding way to the lower pulsation limiting value
Puls.sub.Limit2.
[0024] Methods embodying principles of the present invention make
it possible to operate firing plants close to the lean extinction
limit and, as a result, to significantly lower the NO.sub.x
emissions. At the same time, however, the operating characteristic
of the burner group staging ratio (BGV.sub.Rich) is operated with a
certain safety margin to the lean extinction limit so that a stable
operation of the burners is ensured. This safety margin, however,
is significantly reduced by the described closed-loop control
concept.
TABLE-US-00001 List of designations 1 Measuring device 2 Filter
device 3 Monitoring device 4 Evaluating and control unit
BGV.sub.Rich Burner group staging ratio, operating characteristic
BGV.sub.New Burner group staging ratio after adaptation .DELTA.BGV
Burner group staging ratio, correction value K.sub.Filter
Amplification factor used by the filter device 2 K.sub.PI
Amplification factor used by the evaluating/control unit 4
T.sub.Filter Time constant used by the filter device 2 T.sub.PI
Time constant used by the evaluating/control unit 4 Puls.sub.Limit
Pulsation limiting value Puls.sub.Limit1 Upper pulsation limiting
value Puls.sub.Limit2 Lower pulsation limiting value
Puls.sub.Actual Pressure pulsations measured in the combustion
chamber Puls.sub.Ref Established pulsation reference value
Puls.sub.Actual, Filter Pressure pulsations measured and then
filtered in the combustion chamber Puls.sub.Ref, adapt Adapted or
corrected pulsation reference value
[0025] While the invention has been described in detail with
reference to exemplary embodiments thereof, it will be apparent to
one skilled in the art that various changes can be made, and
equivalents employed, without departing from the scope of the
invention. The foregoing description of the preferred embodiments
of the invention has been presented for purposes of illustration
and description. It is not intended to be exhaustive or to limit
the invention to the precise form disclosed, and modifications and
variations are possible in light of the above teachings or may be
acquired from practice of the invention. The embodiments were
chosen and described in order to explain the principles of the
invention and its practical application to enable one skilled in
the art to utilize the invention in various embodiments as are
suited to the particular use contemplated. It is intended that the
scope of the invention be defined by the claims appended hereto,
and their equivalents. The entirety of each of the aforementioned
documents is incorporated by reference herein.
* * * * *