U.S. patent application number 14/355467 was filed with the patent office on 2014-09-18 for combustion chamber for a gas turbine and burner arrangement.
This patent application is currently assigned to Seimens Aktiengesellschaft. The applicant listed for this patent is SIEMENS AKTIENGESELLSCHAFT. Invention is credited to Christian Beck, Olga Deiss, Werner Krebs, Bernhard Wegner.
Application Number | 20140260265 14/355467 |
Document ID | / |
Family ID | 47115871 |
Filed Date | 2014-09-18 |
United States Patent
Application |
20140260265 |
Kind Code |
A1 |
Beck; Christian ; et
al. |
September 18, 2014 |
COMBUSTION CHAMBER FOR A GAS TURBINE AND BURNER ARRANGEMENT
Abstract
A combustion chamber (10, 20) for a gas turbine (1) with at
least two combustion zones (23, 24) and at least one burner
arrangement (11, 28) for the combustion of a fuel/air mixture in
the combustion zones (23, 24). The burner arrangement (11, 28) has
at least one premixing passage (29) that opens into the combustion
zones (23, 24) to provide a fuel/air mixture, and an air supply
(32) and at least one fuel supply (33) encompassed in the burner
arrangement (11, 28) and open into the premixing passage (29). The
combustion chamber permits a particularly effective damping of
combustion chamber pressure fluctuations. To this end, the air
supply (32) is designed in a stepped manner such that the outlet
openings (34, 34a, 34b, 34c) of the stepped air supply that open
into the premixing passage can be assigned different delay times
(.tau..sub.1, .tau..sub.2, .tau..sub.3), which damps the
fluctuations.
Inventors: |
Beck; Christian; (Essen,
DE) ; Deiss; Olga; (Dusseldorf, DE) ; Krebs;
Werner; (Mulheim an der Ruhr, DE) ; Wegner;
Bernhard; (Berlin, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SIEMENS AKTIENGESELLSCHAFT |
Munchen |
|
DE |
|
|
Assignee: |
Seimens Aktiengesellschaft
Munchen
DE
|
Family ID: |
47115871 |
Appl. No.: |
14/355467 |
Filed: |
October 19, 2012 |
PCT Filed: |
October 19, 2012 |
PCT NO: |
PCT/EP2012/070783 |
371 Date: |
April 30, 2014 |
Current U.S.
Class: |
60/734 |
Current CPC
Class: |
F23R 2900/00014
20130101; F23R 3/28 20130101; F23R 3/286 20130101; F23R 3/346
20130101 |
Class at
Publication: |
60/734 |
International
Class: |
F23R 3/28 20060101
F23R003/28 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 31, 2011 |
EP |
11187285.9 |
Claims
1. A combustion chamber for a gas turbine comprising: at least one
combustion zone and at least one burner arrangement configured for
combustion of a fuel/air mixture in the combustion zone, the burner
arrangement comprising at least one premixing passage which opens
into the combustion zone and which provides a fuel/air mixture, at
least one fuel supply which opens into the premixing passage, and
an air supply which is of stepped form such that it comprises a
plurality of outlet openings, each outlet opening opens into the
premixing passage and is configured to provide air flowing through
the premixing passage to the combustion zone with a respective
different delay time than air provided by the other outlet openings
of the stepped air supply, wherein the delay time is defined as the
time required for a fluid element entering the premixing passage to
pass to the combustion zone, wherein, for a minimum delay time
.tau..sub.min and a maximum delay time .tau..sub.max of the stepped
air supply with regard to a combustion chamber pressure fluctuation
having a frequency f, which fluctuation is to be suppressed, the
following applies: .tau..sub.max-.tau..sub.min>1/f, and the
outlet openings of the stepped air supply, which open into the
premixing passage are arranged such that the density fluctuations,
caused by at least one predominant combustion chamber pressure
fluctuation of frequency f', in the fluid supplied through the
outlet openings are superposed on one another in the premixing
passage owing to the different delay times assigned to the outlet
openings, in such a way that the density fluctuations substantially
cancel one another out.
2. The combustion chamber as claimed in claim 1, further
comprising, the fuel supply which opens into the premixing passage
which is configured to be charged with gaseous fuel also is of
stepped form.
3. The combustion chamber as claimed in claim 1, further
comprising: the at least one combustion zone comprises a first
combustion zone followed downstream by a second combustion zone;
the burner arrangement is arranged in the region of a second axial
stage of the combustion zone and includes at least one premixing
passage that opens into the second combustion zone (24), and a
second burner arrangement in the first combustion zone.
4. The combustion chamber as claimed in claim 3, further
comprising: the burner arrangement comprises a fuel distributor
ring arranged around an outside of a combustion chamber housing
around the combustion zone and the burner arrangement comprises
multiple premixing passages, each being open at one end thereof
into the second combustion zone in the combustion chamber housing
and each corresponding to at least one fuel supply that branches
off from the fuel distributor ring into the premixing passage,
wherein a plurality of the outlet openings of a stepped air supply
are distributed along at least one of the premixing passages.
5. A gas turbine comprising at least one of the combustion
chambers, as claimed in claim 1.
6. (canceled)
7. The combustion chamber as claimed in claim 1, further comprising
the outlet openings being located distributed along the premixing
passage, thereby to cause the minimum and maximum delay times by
the location of the openings.
Description
[0001] The invention relates to a combustion chamber for a gas
turbine having at least one combustion zone and at least one burner
arrangement for the combustion of a fuel/air mixture, wherein the
burner arrangement comprises at least one premixing passage which
opens into the combustion zone and which serves for the provision
of a fuel/air mixture, and an air supply encompassed by the burner
arrangement and at least one fuel supply open into the premixing
passage.
[0002] The invention also relates to a gas turbine having a
combustion chamber of said type and to a burner arrangement.
[0003] Known gas turbines comprise a compressor and a turbine in
addition to a combustion chamber as mentioned in the introduction.
The compressor compresses the air supplied to the gas turbine,
wherein a part of said air serves for the combustion of fuel in the
combustion chamber and a part is used for cooling the gas turbine
and/or the combustion gases. The hot gases provided in the
combustion chamber as a result of the combustion process are
introduced from the combustion chamber into the turbine, wherein
said gases expand and cool therein and, performing work, set
turbine blades in rotation in the process. By means of said
rotational energy, the gas turbine drives a work machine. The work
machine may for example be a generator.
[0004] The fuel/air mixture provided by the at least one burner
arrangement is premixed in the at least one premixing passage for
then being ignited after flowing into the combustion zone. The
premixing of the fuel with the air reduces the pollutant emissions
generated during the combustion in relation to the hitherto
conventional direct injection of the fuel into the combustion zone.
A disadvantage of the premixing of the fuel is however that said
arrangement is significantly more susceptible to the occurrence of
combustion chamber pressure fluctuations. If pressure fluctuations
occur in the combustion zone, concentration fluctuations in the
fuel/air mixture in the premixing passage also arise, which lead to
heat release fluctuations during the combustion. These
thermoacoustic instabilities in turn intensify the combustion
chamber pressure fluctuations, wherein, in the arrangement, there
are predominant frequencies for these escalating combustion chamber
pressure fluctuations. The concentration fluctuations in the
fuel/air mixture, that is to say variations in the fuel/air mixture
ratio over time, may also be referred to as air number
fluctuations. The air number fluctuations result from varying
acoustic resistances of the air supply and fuel supply. For damping
the combustion chamber pressure fluctuations, known gas turbines
have resonators arranged in the housing. Since the resonators
directly adjoin the combustion zone and furthermore interrupt a
heat shield arrangement in the housing and must therefore be
cooled, such a design of the combustion chamber is cumbersome. An
alternative design of a known combustion chamber provides, for the
suppression of such combustion chamber pressure fluctuations, that
the fuel nozzles that open into the premixing passage are arranged
so as to be distributed in the axial direction along the premixing
passage, such that mixing zones with different delay times are
formed in the premixing passage. Said stepped design of the fuel
supply makes it possible for the concentration fluctuations, caused
by the combustion chamber pressure fluctuation, in the fuel
injected through the fuel supply to be smoothed. The fuel nozzles
may also be referred to as outlet openings of the fuel supply.
[0005] It is an object of the invention to specify a combustion
chamber of the type mentioned in the introduction, a gas turbine
having a combustion chamber of said type, and also a burner
arrangement encompassed by a combustion chamber of said type, which
permits particularly effective damping of combustion chamber
pressure fluctuations.
[0006] The object is achieved according to the invention, in the
case of a combustion chamber of the type mentioned in the
introduction, in that the air supply is of stepped form such that
outlet openings, which open into the premixing passage, of the
stepped air supply can be assigned different delay times.
[0007] By means of the known fuel supply with fuel nozzles arranged
so as to be distributed in the axial direction along the premixing
passage, it is indeed possible to compensate for fluctuations,
caused by combustion chamber pressure fluctuations, in the fuel
flow rate admixed to the air stream along the premixing passage.
However, owing to the different acoustic resistances of the air and
of the fuel, said known stepped configuration is not suitable for
injecting the fuel into the air stream in such a way that a
constant ratio of fuel and air and a constant fuel flow rate per
unit of time exits the premixing passage and enters the combustion
zone. Therefore, according to the invention, for the suppression of
combustion chamber pressure fluctuations and thus also of heat
release fluctuations, it is proposed that the air supply that opens
into the premixing passage be of stepped form, and thus the density
fluctuations, caused by combustion chamber pressure fluctuations,
in the air stream passing through the premixing passage be
smoothed. Owing to the high compressibility of air in relation to,
for example, a liquid fuel, and the relatively low pressure in the
air supply line in relation to the pressure in the fuel supply
line, this is particularly effective for the suppression of
combustion chamber pressure fluctuations.
[0008] According to the invention, the stepped air supply comprises
outlet openings that open into the premixing passage, which outlet
openings can be assigned different delay times. The stepped air
supply may furthermore comprise further outlet openings which may
be assigned redundant delay times. The delay time may also be
referred to as a convective time delay. Said time delay is defined
as the time required for a fluid element entering the premixing
passage to pass to the combustion zone. The outlet openings may
also be referred to as exit openings.
[0009] The burner arrangement may for example comprise a pilot
burner with a premixing passage with pilot burner lance arranged
centrally therein, wherein the pilot burner lance is connected to a
fuel supply and comprises fuel nozzles. An air supply opens into
the premixing passage of the pilot burner. Around the pilot burner
there may be arranged a multiplicity of main mixers encompassed by
the burner arrangement. Each of the main mixers may have a
premixing passage encompassed by a cylindrical housing, into which
premixing passage an air supply opens, and axially in which
premixing passage there is arranged a lance which is connected to a
fuel supply and which has fuel nozzles. The lance may for example
be supported on the housing via swirl vanes. According to the
invention, in the case of the burner arrangement specified by way
of example, at least one of the premixing passages comprises a
stepped air supply. It is for example possible for the air supply
of each of the main mixers to be of stepped form by virtue of the
swirl vanes forming air outlet openings which open into the
premixing passage and which can be assigned different delay times.
Said delay times may preferably be selected such that, at least in
the frequency range of a predominant combustion chamber pressure
fluctuation, density fluctuations caused by the latter in the
supplied air cancel one another out, or attenuate one another,
owing to the different delay times of the air outlet openings.
[0010] One advantageous refinement of the invention may provide
that, in addition to the air supply of stepped form, a fuel supply
which opens into the premixing passage and which can be charged
with gaseous fuel is likewise of stepped form.
[0011] Since the gaseous fuel likewise exhibits high
compressibility in relation to air, the additional stepped
configuration of the fuel supply that can be charged with gaseous
fuel makes it possible for fluctuations, caused by combustion
chamber pressure fluctuations, in concentration and density of the
fuel/air mixture flowing out of the premixing passage into the
combustion zone to be dampened with even greater effectiveness. If
the premixing passage comprises more than one fuel supply that can
be charged with gaseous fuel, it is possible for one or more of
said fuel supplies that can be charged with gaseous fuel to be of
stepped form.
[0012] It may advantageously also be provided that the outlet
openings of the stepped supply can be assigned delay times,
wherein, for a minimum delay time .tau..sub.min and a maximum delay
time .tau..sub.max with regard to a combustion chamber pressure
fluctuation, of frequency f, which is to be suppressed, the
following applies: .tau..sub.max-.tau..sub.min>1/f.
[0013] By means of said condition, it is ensured that, at least in
the frequency range of the combustion chamber pressure fluctuation
to be suppressed, density fluctuations, caused by the latter, in
the fluid supplied through the stepped supply are attenuated in an
effective manner. The stepped supply is the stepped air supply. If
yet further supplies that open into the premixing passage are of
stepped form, the condition may also apply to said supplies. The
minimum and maximum delay times specified in the condition relate
respectively to the shortest and the longest of the delay times
assigned to the outlet openings of a supply.
[0014] It may also be considered advantageous for the outlet
openings, which open into the premixing passage, of the stepped
supply to be arranged such that density fluctuations, caused by at
least one predominant combustion chamber pressure fluctuation of
frequency f', in the fluid supplied through the outlet openings are
superposed on one another in the premixing passage owing to the
different delay times assigned to the outlet openings, in such a
way that said density fluctuations substantially cancel one another
out.
[0015] In one advantageous refinement of the invention, it may be
provided that the burner arrangement is arranged in the region of a
second axial stage, with at least one premixing passage that opens
into the combustion zone, wherein the combustion zone follows
downstream of a first combustion zone with a first burner
arrangement.
[0016] By means of a second axial stage, the heat release can be
distributed further over the entire available combustion chamber,
such that the susceptibility of the combustion system to
thermoacoustic instabilities is further reduced. Furthermore, a
stepped air supply to at least one premixing passage of the burner
arrangement of the second axial stage can be realized particularly
easily in terms of apparatus.
[0017] A preferred refinement of the invention may provide that the
burner arrangement comprises a fuel distributor ring arranged
around the outside of a combustion chamber housing and comprises
multiple premixing passages, wherein the premixing passages open at
one end thereof into the combustion zone in the combustion chamber
housing and correspond to at least one fuel supply that branches
off from the fuel distributor ring, wherein outlet openings of a
stepped air supply are arranged so as to be distributed at least
along one of the premixing passages.
[0018] Said stepped air supply to at least one premixing passage of
the burner arrangement of the second axial stage can be realized
particularly easily in terms of apparatus. The premixing passages
may for example be of hose-like form, wherein, for the present
invention, it is very generally the case that the position of the
air outlet openings along the premixing passages, or the delay
times corresponding thereto, may be adaptable to the frequency of
the combustion chamber pressure fluctuations to be suppressed. For
example, the hose-like premixing passage may be composed of elastic
material, wherein the length of said premixing passage--and thus
also the delay times corresponding to the outlet openings--can be
adapted to a frequency to be suppressed.
[0019] It is a further object of the invention to specify a gas
turbine having at least one combustion chamber as mentioned in the
introduction, which permits particularly effective damping of
combustion chamber pressure fluctuations.
[0020] For this purpose, the gas turbine has at least one
combustion chamber which is designed as claimed in one of claims 1
to 4.
[0021] It is a further object of the invention to specify a burner
arrangement which is encompassed by the combustion chamber
mentioned in the introduction and which permits particularly
effective damping of combustion chamber pressure fluctuations.
[0022] For this purpose, the burner arrangement is a constituent
part of the combustion chamber as claimed in one of claims 1 to
4.
[0023] Further expedient refinements and advantages of the
invention are described in the description of exemplary embodiments
of the invention with reference to the figure of the drawing,
wherein the same reference signs are used for equivalent
components.
[0024] In the drawing:
[0025] FIG. 1 shows a schematic sectional view of a gas turbine
according to the prior art,
[0026] FIG. 2 shows, in a schematic sectional view, a detail of a
combustion chamber with a second axial stage according to an
exemplary embodiment of the invention, and
[0027] FIG. 3 shows, in a schematic sectional view, a detail view
of the exemplary embodiment illustrated in FIG. 2 in the region of
the stepped air supply.
[0028] FIG. 1 shows a schematic sectional view of a gas turbine 1
according to the prior art. The gas turbine 1 has, in the interior,
a rotor 3 which is mounted so as to be rotatable about an axis of
rotation 2 and which has a shaft 4 also referred to as turbine
rotor. Arranged in succession along the rotor 3 are an intake
housing 6, a compressor 8, a combustion system 9, a turbine 14 and
an exhaust-gas housing 15, the combustion system having a number of
combustion chambers 10 which each comprise a burner arrangement 11
and a combustion chamber housing 12.
[0029] The combustion system 9 communicates with a hot-gas duct,
which is for example of annular form. There, multiple turbine
stages positioned in series form the turbine 14. Each turbine stage
is formed from vane rings. In the hot duct, as viewed in the flow
direction of a working medium, a row formed from guide vanes 17 is
followed by a row formed from rotor vanes 18. The guide vanes 17
are in this case fastened to an inner housing of a stator 19,
whereas the rotor vanes 18 of a row are for example attached by
means of a turbine disk to the rotor 3. A generator (not
illustrated), for example, is coupled to the rotor 3.
[0030] During the operation of the gas turbine, air is drawn in
through the intake housing 6, and compressed, by the compressor 8.
The compressed air provided at the turbine-side end of the
compressor 8 is conducted to the combustion system 9 and mixed
there with a fuel in the region of the burner arrangement 11.
[0031] The mixture is then burned with the aid of the burner
arrangement 11, such that a working gas stream is formed in the
combustion system 9. From there, the working gas stream flows along
the hot-gas duct past the guide vanes 17 and the rotor vanes 18. At
the rotor vanes 18, the working gas stream expands with a
transmission of impetus, such that the rotor vanes 18 drive the
rotor 3, and the latter drives the generator (not illustrated)
coupled thereto.
[0032] FIG. 2 shows a detail of a combustion chamber 20 of a gas
turbine according to an exemplary embodiment of the invention. The
combustion chamber 20 has a combustion chamber housing 21 which is
formed rotationally symmetrically about an axis 22. In the
combustion chamber housing 21 there is situated a first combustion
zone 23 and a second combustion zone 24, wherein the second
combustion zone 24 follows downstream of the first combustion zone
23 in relation to a main flow direction 26. The combustion chamber
20 comprises a first burner arrangement (not illustrated) and a
second burner arrangement 28 for the combustion of a fuel/air
mixture in the second combustion zone 24. The second burner
arrangement 28 comprises a premixing passage 29 which opens into
the second combustion zone 24 and which serves for the provision of
a fuel/air mixture, wherein an air supply 32, which is encompassed
by the second burner arrangement 28, and a fuel supply 33 open into
the premixing passage 29, wherein the air supply 32 is of stepped
form such that the outlet openings 34, which open into the
premixing passage 29, of the stepped air supply 32 can be assigned
different delay times.
[0033] The second burner arrangement 28 is thus arranged in the
region of a second axial stage. The second burner arrangement 28
comprises a fuel distributor ring 36 arranged around the outside of
the combustion chamber housing 21 and comprises multiple premixing
passages 29, wherein the premixing passages 29 open at one end 37
thereof into the second combustion zone 24 in the combustion
chamber housing 21 and correspond in each case to a fuel supply 33
that branches off from the fuel distributor ring 36, wherein outlet
openings 34 of a stepped air supply 32 are arranged so as to be
distributed along at least one of the premixing passages 29.
[0034] In one advantageous refinement of the illustrated exemplary
embodiment of the invention, each of the premixing passages 29 of
the second burner arrangement 28 may have a stepped air supply
32.
[0035] The fuel injected through the fuel supply 33 into the
premixing passage 29 mixes with the air entering the premixing
passage 29 through the outlet openings 34, such that a fuel/air
mixture flows along the premixing passage in the flow direction 39.
An air volume exiting an outlet opening 34 will mix with the fuel
and, here, proceeding from the position of the outlet opening 34,
will require a time period in order to pass into the combustion
zone 24. Said time period is referred to as delay time and is
defined as the time required for a fluid element entering the
premixing passage to pass to the combustion zone. The outlet
openings 34 arranged along the premixing passage 29 correspond,
owing to their differing arrangement in the premixing passage 29,
to different delay times. Each of the outlet openings 34 in the
premixing passage 29 can thus be assigned different delay
times.
[0036] FIG. 3 shows a detail view of the combustion chamber
according to the invention illustrated in FIG. 2, according to an
exemplary embodiment, in the region of the second burner
arrangement of a second axial stage. The illustration shows a
section of the combustion chamber housing 21 which surrounds a
first combustion zone 23 (partially illustrated) and a second
combustion zone 24 (partially illustrated) that adjoins said first
combustion zone downstream, wherein a premixing passage 29 which is
encompassed by the second burner arrangement and which serves for
the provision of a fuel/air mixture opens into the second
combustion zone 24. Into the premixing passage 29 which is of
hose-like form there opens a fuel supply 33, which serves for the
injection of fuel 35 into the premixing passage 29, and an air
supply 32 which is of stepped form. The air supply 32 which is of
stepped form comprises outlet openings 34a, 34b, 34c which open
into the premixing passage 29 and which serve for the supply of air
40, wherein the outlet openings 34a, 34b, 34c can be assigned
different delay times .tau..sub.1, .tau..sub.2, .tau..sub.3. For
example, an air volume exiting the outlet opening 34a will mix with
the fuel 35 which has been injected through the fuel supply 33 and
which is flowing past, and here, proceeding from the position of
the outlet opening 34a, will require a time period .tau..sub.1 to
pass into the second combustion zone 24. For the damping or
suppression of a combustion chamber pressure fluctuation of
frequency f, the position of the outlet openings 34a, 34b and 34c
may advantageously be selected such that
.tau..sub.1-.tau..sub.3>1/f. The density fluctuations of the air
caused by the combustion chamber pressure fluctuation of frequency
f in the outlet openings can, owing to the different delay times
.tau..sub.1, .tau..sub.2, .tau..sub.3, be superposed during the
ignition of the fuel/air mixture in the second combustion zone 24
such that said density fluctuations substantially cancel one
another out. The arrangement of the outlet openings 34a, 34b, 34c
along the premixing passage 29 may be selected correspondingly for
this purpose. The combustion chamber pressure fluctuation of
frequency f may be a combustion chamber pressure fluctuation that
can be predominantly excited owing to the configuration of the
combustion chamber. This may also be referred to as predominant
combustion chamber pressure fluctuation. One refinement of the
illustrated exemplary embodiment may also provide that the fuel
supply 33 is likewise of stepped form (not illustrated here).
* * * * *