U.S. patent application number 14/911766 was filed with the patent office on 2016-07-07 for burner for a gas turbine and method for reducing thermoacoustic oscillations in a gas turbine.
This patent application is currently assigned to Siemens Aktiengesellschaft. The applicant listed for this patent is SIEMENS AKTIENGESELLSCHAFT. Invention is credited to Berthold Kostlin, Bernd Prade.
Application Number | 20160195271 14/911766 |
Document ID | / |
Family ID | 49226063 |
Filed Date | 2016-07-07 |
United States Patent
Application |
20160195271 |
Kind Code |
A1 |
Kostlin; Berthold ; et
al. |
July 7, 2016 |
BURNER FOR A GAS TURBINE AND METHOD FOR REDUCING THERMOACOUSTIC
OSCILLATIONS IN A GAS TURBINE
Abstract
A burner for a gas turbine, has an air passage supplied with
compressed air and a fuel passage supplied with fuel gas, each
passage has a main outlet opening leading into the combustion
chamber of the gas turbine, the air and fuel passages connected
fluidically together via a connection duct arranged upstream of the
main outlet openings. The burner is configured such that, when air
passage is supplied with compressed air and fuel passage is
supplied with fuel gas, a portion of the fuel gas flowing in the
fuel passage flows via at least one connection duct into the air
passage and, for combustion thereof, is introduced through the main
outlet opening of the air passage into the interior of the
combustion chamber and a remaining portion of the fuel gas is
introduced through the main outlet opening of the fuel passage into
the interior of the combustion chamber.
Inventors: |
Kostlin; Berthold;
(Duisburg, DE) ; Prade; Bernd; (Mulheim,
DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SIEMENS AKTIENGESELLSCHAFT |
Munchen |
|
DE |
|
|
Assignee: |
Siemens Aktiengesellschaft
Munich
DE
|
Family ID: |
49226063 |
Appl. No.: |
14/911766 |
Filed: |
September 23, 2014 |
PCT Filed: |
September 23, 2014 |
PCT NO: |
PCT/EP2014/070168 |
371 Date: |
February 12, 2016 |
Current U.S.
Class: |
60/772 ; 60/725;
60/737 |
Current CPC
Class: |
F23R 3/346 20130101;
F23D 14/70 20130101; F23D 2900/00008 20130101; F23R 2900/00002
20130101; F23R 2900/00013 20130101; F23C 2900/06043 20130101; F23M
20/005 20150115; F23R 3/286 20130101 |
International
Class: |
F23M 20/00 20060101
F23M020/00; F23R 3/28 20060101 F23R003/28 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 23, 2013 |
EP |
13185537.1 |
Claims
1.-22. (canceled)
23. A burner for a gas turbine, comprising: at least one air
passage to which compressed air is supplied and at least one fuel
passage to which at least one fuel gas is supplied, the two
passages each comprising a main outlet opening leading into the
combustion chamber of the gas turbine, the air passage and the fuel
passage being connected fluidically together via at least one
connection duct arranged upstream of the main outlet openings,
wherein the burner is configured such that, in at least one first
operating state of the burner, when air passage is supplied with
compressed air and fuel passage is supplied with fuel gas, a
portion of the fuel gas flowing in the fuel passage flows via at
least one connection duct into the air passage and, for combustion
thereof, is introduced through the main outlet opening of the air
passage into the interior of the combustion chamber and a remaining
portion of the fuel gas is introduced through the main outlet
opening of the fuel passage into the interior of the combustion
chamber, and at least one adjusting element arranged in the region
of the connection ducts, such that the fraction and/or the radial
inflow profile and/or the division over the connection ducts of the
fuel gas branched off from the fuel passage into the air passage is
adjusted and/or adjustable by the at least one adjusting element,
such that fluctuations in heat release are fed back to a lesser
extent into the pressure fluctuations in the combustion
chamber.
24. The burner as claimed in claim 23, wherein the burner is
configured such that the common dwell time profile, brought about
by the branching off, of the remaining portion and of the
branched-off portion of the fuel stream is adapted to the
thermoacoustic behavior of the combustion chamber, such that
fluctuations in heat release are fed back to a lesser extent into
the pressure fluctuations in the combustion chamber.
25. The burner as claimed in claim 23, wherein the burner is
arranged substantially rotationally symmetrically about a
longitudinal axis, such that a main direction of flow of the fluid
flowing in the passages of the burner points in the direction of
the longitudinal axis or has at least one component in the
direction of the longitudinal axis, and the air passage and the
fuel passage are arranged coaxially to one another at least in
places.
26. The burner as claimed in claim 23, wherein the main outlet
openings of the air passage and fuel passage are arranged such that
the coaxially surrounding passage is arranged around the other main
outlet opening relative to a projection plane extending
perpendicular to the longitudinal axis.
27. The burner as claimed in claim 23, wherein the air passage and
the fuel passage adjoin one another at least in places along a wall
which substantially takes the form of a cylindrical casing and/or
of a truncated cone-shaped casing, wherein the connection ducts
take the form of holes in the wall.
28. The burner as claimed in claim 23, further comprising: a flow
guide arranged in the fuel gas passage downstream of at least one
fuel passage-side inlet opening of a connection duct, wherein the
flow guide increases the static pressure in the region of the inlet
openings of the connection duct when the fuel passage is supplied
with fuel gas.
29. The burner as claimed in claim 28, wherein the flow guide
comprises a substantially annular metal plate, wherein the metal
plate is arranged circumferentially on an inside of a wall
delimiting the fuel passage.
30. The burner as claimed in claim 29, wherein the metal plate
extends into the interior of the fuel passage at an angle contrary
to a main direction of flow in the fuel passage.
31. The burner as claimed in claim 29, wherein the metal plate in
each case has a cut-out between the regions located downstream of
the inlet openings of the connection ducts.
32. The burner as claimed in claim 28, wherein the adjusting
element comprises a number of flow guides, which take the form of
triangular or trapezoidal metal plates.
33. The burner as claimed in claim 28, wherein the flow guide
comprises at least one cupped element with an entry opening, which
is arranged with the entry opening pointing towards the inlet
opening of a connection duct downstream of the inlet opening on an
inside of a wall delimiting the fuel passage.
34. The burner as claimed in claim 33, wherein the cupped element
substantially takes the form of a hollow quarter-sphere.
35. The burner as claimed in claim 23, wherein at least one
adjusting element is of tubular configuration, wherein the tubular
adjusting element is in each case arranged at least in part in one
of the connection ducts.
36. A combustion chamber, comprising: at least one burner, wherein
the burner is configured as in claim 23.
37. A gas turbine, comprising: at least one combustion chamber,
wherein the combustion chamber is configured as in claim 36.
38. A method for reducing thermoacoustic oscillations in a gas
turbine comprising at least one burner, the method comprising:
adapting a dwell time profile of a fuel stream flowing in a first
fuel passage of the burner to the thermoacoustic behavior of the
combustion chamber, wherein, to adapt the dwell time profile, a
remaining portion of the fuel stream is introduced into the
combustion chamber through at least one main outlet opening of the
first passage and a branched-off portion of the fuel stream is
introduced, downstream of introduction thereof into the fuel
passage and upstream of the main outlet opening, into at least one
second passage via at least one connection duct branching off from
the first passage, wherein the branched-off portion of the fuel
stream is introduced into the combustion chamber separately from
the remaining fuel stream, such that the sub-streams, after exit
thereof from the burner, are combusted in the combustion chamber
with different dwell times or dwell time profiles, adjusting the
fraction and/or the inflow profile and/or the division over the at
least one connection duct of the branched-of portion of the fuel
stream prior to start-up of the burner and/or during operation of
the burner, wherein adjustment of the fraction and/or the
penetration depth and/or the division over the at least one
connection duct proceeds by adapting at least one flow guide
arranged in the fuel passage and/or one adjusting element arranged
in the region of the connection ducts, such that fluctuations in
heat release are fed back to a lesser extent into the pressure
fluctuations in the combustion chamber.
39. The method as claimed in claim 38, further comprising:
introducing the remaining fuel stream and the branched-off portion
of the fuel stream substantially coaxially to one another into the
combustion chamber.
40. The method as claimed in claim 38, wherein adaptation of the at
least one flow guide and/or of the at least one adjusting element
proceeds by exchange of the flow guide and/or the adjusting element
and/or adaptation of the shape and/or position thereof.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is the US National Stage of International
Application No. PCT/EP2014/070168 filed Sep. 23, 2014, and claims
the benefit thereof. The International Application claims the
benefit of European Application No. EP13185537 filed Sep. 23, 2013.
All of the applications are incorporated by reference herein in
their entirety.
FIELD OF INVENTION
[0002] The invention relates to a burner for a gas turbine which is
intended in particular for the combustion of low calorie fuel gas.
The invention also relates to a method for reducing thermoacoustic
oscillations in a gas turbine, wherein the burner is suitable for
carrying out the method.
BACKGROUND OF INVENTION
[0003] In a combustion chamber interaction may arise between
acoustic oscillations (pressure fluctuations) and fluctuations in
heat release, which may amplify one another. Such thermoacoustic
oscillations, which arise in particular in the combustion chamber
of a gas turbine, may lead to considerable damage to the components
during operation of the gas turbine and force shutdown of the
installation.
[0004] In a method for reducing thermoacoustic oscillations in a
gas turbine comprising at least one burner, a dwell time profile of
a fuel stream flowing in a first fuel passage of the burner is
adapted to reduce the thermoacoustic oscillations.
[0005] To provide a fuel gas to be combusted in the combustion
chamber of the gas turbine, the burner of the type in question
comprises at least the above-stated first fuel passage to which
fuel gas may be supplied and, to provide the air required for
combustion, an air passage to which compressed air may be supplied.
The two passages each comprise a main outlet opening leading into
the combustion chamber of the gas turbine. The fuel passage may
take the form of a premixing passage or a diffusion passage. To
this end, the fuel passage is connected to at least one feed for
the fuel gas. The fuel passage is preferably configured to provide
synthesis gas--in particular in the form of an annular space
passage. The burner may comprise further passages, for example in
order to introduce a plurality of different fuels into the
combustion chamber with the burner for combustion. The individual
passages may also be connected to a plurality of feed systems, in
order to supply different fuels or flushing fluids to the passages,
depending on the operating state of the burner.
[0006] So that such burners may also without risk adopt operating
states in which fuel feed to the above-stated fuel passage is shut
off (so as to supply another passage with another fuel), it is
known from the prior art to provide such burners with flushing air
ducts, so as to avoid flareback into the fuel passage. In known
burners, compressed air from the air passage is introduced into the
fuel passage through these flushing air ducts when fuel feed has
been shut off. In these known burners, fuel gases penetrating via
the main outlet opening into the passage are flushed out of the
passage by the compressed air. This prevents flareback into the
burner.
[0007] A burner of the type in question comprises at least one
connection duct which is arranged upstream of the main outlet
openings and connects the air passage and the fuel passage together
fluidically.
[0008] Burners are known from the prior art which, to widen a dwell
time profile of a fuel gas stream flowing in a first fuel passage,
comprise a number of fuel nozzles which lead into the first fuel
passage and are arranged offset relative to one another in the
direction of flow.
SUMMARY OF INVENTION
[0009] The object of the present invention is to provide a burner
and a method of the above-stated type which allow an alternative
way of reducing thermoacoustic oscillations in a combustion chamber
of a gas turbine.
[0010] The object is achieved according to the invention for a
burner of the above-stated type in that the burner is configured
such that in at least one first operating state of the burner, when
compressed air is supplied to the air passage and fuel gas is
supplied to the fuel passage, a portion of the fuel gas flowing in
the fuel passage flows into the air passage via at least one
connection duct. The branched-off portion of the fuel stream may be
introduced for combustion thereof into the interior of the
combustion chamber through the main outlet opening of the air
passage. A portion remaining in the fuel passage of the fuel gas
may be introduced into the interior of the combustion chamber
through the main outlet opening of the fuel passage. The amount and
radial fuel distribution of the branched-off portion of the fuel
stream is such that fluctuations in heat release are fed back to a
lesser extent into the pressure fluctuations in the combustion
chamber.
[0011] The invention is based on the recognition that the radial
distribution of the fuel, in particular in the case of a synthesis
gas/air mixture, plays a crucial role in the acoustic stability of
the burner. The burner according to the invention allows better
acoustic stability, so widening the operating range of the burner
with regard to load and fuel quality.
[0012] In the burner according to the invention, the radial
fuel/air distribution of a fuel stream flowing in a fuel passage
may be adapted without fundamental aerodynamic design parameters of
the fuel passage, such as swirl number, pressure drop and main
dimensions of the passages, having to be modified significantly.
The invention also makes it possible to adapt the burner to the
thermoacoustic behavior of the combustion chamber for different
fuel compositions without adaptation of the entire fuel passage
being necessary for this purpose.
[0013] The burner according to the invention is such that, in at
least one first operating state of the burner, when compressed air
is supplied to the air passage and fuel gas is supplied to the fuel
passage, the static pressure prevailing at the connection ducts
serving in branching off the fuel is greater on the fuel passage
side than on the air passage side.
[0014] According to the invention, the burner is configured such
that the fuel stream is divided once it is flowing in the fuel
passage. Thus, according to the invention, no division takes place
in the region of the fuel feed system; rather, the
division/branching off takes place after introduction of the fuel
into the fuel passage but upstream of the main outlet opening.
[0015] According to the invention, the burner is configured such
that, through the division/branching off of the fuel stream flowing
in the first fuel passage, fluctuations in heat release are fed
back to a lesser extent into the pressure fluctuations in the
combustion chamber.
[0016] By dividing and branching off the fuel stream flowing in the
first fuel passage, the flame front in front of the burner is
modified. This may be adjusted by means of the amount and radial
distribution of the branched-off portion of the fuel stream such
that fluctuations in heat release are fed back to a lesser extent
into the pressure fluctuations in the combustion chamber. To
achieve an appropriate modification of the flame front, the radial
fuel distribution of the branched-off portion of the fuel stream
extends substantially beyond the thickness of a shear layer arising
between the exiting streams into the air passage.
[0017] The invention thus does not relate to manipulation of the
thickness of the shear layer between the compressed air stream
exiting from the air passage and the fuel stream exiting from the
main outlet opening of the fuel passage. Instead, to ensure that
fluctuations in heat release are fed back to a lesser extent into
the pressure fluctuations in the combustion chamber, the invention
takes another course, in that the amount and radial fuel
distribution of a branched-off portion of the fuel gas flowing in
the fuel passage is such that, through modification of the flame
front (which accompanies modification of the dwell time profile of
the fuel stream), fluctuations in heat release are fed back to a
lesser extent into the pressure fluctuations in the combustion
chamber.
[0018] To bring about the desired branching off of the portion of
the fuel stream, the position of the connection ducts and their
diameter may be selected accordingly in the two passages. However,
to produce suitable pressure conditions at the connection ducts,
the invention is in particular based on the burner comprising flow
guide means in the fuel passage and/or adjusting elements in the
region of the connection ducts, which suitably determine the static
pressure in the inlet region of the connection ducts. The flow
guide means and/or adjusting elements may be modified for example
in position or shape or be exchanged to adapt the
division/branching off of the fuel stream. In this way, the
position of the connection ducts in the passages is freely and
widely selectable. The connection ducts are in this case arranged
downstream of the air feed lines and/or fuel gas feed line used in
the first operating state and upstream of the two main outlet
openings of the two passages, so that fuel gas may be branched off
into the air stream.
[0019] The main outlet opening may for example take the form of an
annular opening at the outlet orifice of the passage. According to
a further exemplary embodiment, the main outlet opening may consist
of a plurality of holes in a metal plate (covering the outlet
orifice of the burner passage). The main outlet opening is arranged
at the combustion chamber end of the passage.
[0020] The connection ducts are arranged along a wall delimiting
the fuel passage, for example in a circumferential sequence, such
that their inlet openings are arranged in a circumferential row in
the fuel passage and the ducts extend through the wall as far as
the air passage. The pressure conditions in the burner may be
configured such that the connection ducts also counteract flareback
into the burner when the supply of fuel into the first fuel passage
has been shut off.
[0021] Advantageous configurations of the invention are indicated
in the following description and the subclaims, the features of
which may be applied individually and in any desired
combination.
[0022] Provision may advantageously be made for the burner to be
configured such that the common dwell time profile, brought about
by the branching off, of the remaining portion and the branched-off
portion of the fuel stream is adapted to the thermoacoustic
behavior of the combustion chamber, such that fluctuations in heat
release are fed back to a lesser extent into the pressure
fluctuations in the combustion chamber.
[0023] By dividing and branching off the fuel stream flowing in the
first fuel passage, the flame front in front of the burner is
modified. A modified common dwell time profile of the branched-off
and remaining portions of the fuel stream may thus be established.
The dwell time is here the interval of time which the fuel needs
from outlet from the burner to the flame front. Since the fuel in
the fuel stream has different dwell times (depending on exit
location at the burner outlet and depending on the position of the
flame in front of the exit location), a dwell time profile of the
fuel stream is established for the respective operating state.
Undesired feedback of fluctuations in heat release into pressure
fluctuations in the combustion chamber may be reduced by means of
the division and branching off of the fuel stream, since the common
dwell time profile may be modified depending on amount and radial
fuel profile of the branched-off portion of the fuel stream. If for
example the fraction of the profile is reduced the dwell time of
which corresponds substantially to the frequency of a particular
fuel chamber pressure fluctuation, this reduces feedback of
fluctuations in heat release into pressure fluctuations in the
combustion chamber.
[0024] The configuration according to the invention of the burner
is thus such that, at least in the first operating state, a dwell
time profile of the fuel stream having a damping or non-amplifying
effect on the thermoacoustic behavior of the fuel chamber is
brought about.
[0025] The phrase "thermoacoustic oscillation behavior" means that
gas turbine combustion chambers tend, depending on power range, in
particular at specific frequencies/frequency bands, to amplify
thermoacoustic oscillations (characteristic ripple behavior). These
frequencies may also be referred to as particular combustion
chamber pressure fluctuations. If the dwell time profile of a
burner is appropriately adjusted, in particular widened, this may
counteract amplification of the oscillations in the range of at
least one such characteristic ripple frequency/frequency band. In
this respect, the dwell time profile may be adapted to or
harmonized with the thermoacoustic behavior of the combustion
chamber and counteract amplification of thermoacoustic oscillations
in the combustion chamber. The dwell time profile may be influenced
for example by means of the fraction and/or penetration depth
(radial profile) and/or division over the individual connection
ducts of the branched-off fuel stream. In relation to the first
fuel passage, the burner comprises appropriately configured
branching-off which, at least in the first operating state, brings
about a fuel stream dwell time profile which has a damping effect
on the thermoacoustic behavior of the combustion chamber.
[0026] In one advantageous configuration of the invention, the
first fuel passage may be designed at least for supply with low
calorie fuel gas.
[0027] A low calorie fuel should (in contrast to a standard fuel)
be understood in particular to mean a fuel with a calorific value
of less than 20 MJ/kg, in particular of less than 10 MJ/kg. This
could for example be a very low calorie natural gas or a "synthesis
gas". Synthesis gas conventionally comprises main fractions of CO
and H.sub.2 and optionally secondary fractions such as N.sub.2 and
CO.sub.2 together with water vapor. Standard fuel is conventionally
a normal and/or high calorie fuel, the calorific value of which is
far higher than 30 MJ/kg. Normal natural gas for example has as a
rule a calorific value of between 40 and 50 MJ/kg. The combustible
component of standard fuels for gas turbines consists substantially
of hydrocarbons. In contrast, the combustible components of
synthesis gas are substantially CO and H.sub.2. Due to the low
calorific value, high volumetric flow rates of fuel gas must
consequently be supplied to the combustion chamber by the burner.
The consequence of this is that, for the combustion of low calorie
combustion fuels, such as for example synthesis gas, one or more
separate fuel passages must be provided. Because of the high
reactivity of synthesis gases compared to conventional combustion
fuels such as natural gas and oil, there is a distinctly higher
risk of flareback.
[0028] The present invention may be applied particularly
advantageously to this fuel passage for low calorie fuels.
[0029] The fuel passage may be configured for diffusion operation
or for premixing operation to introduce the low calorie fuel gas
into the combustion chamber. In premixing operation, the low
calorie fuel gas, which may in particular be synthesis gas, is
premixed with air to yield a low calorie fuel/air mixture and
reaction of the low calorie fuel/air mixture in the fuel passage is
avoided, such that the fuel/air mixture is reacted to yield a hot
gas only in the combustion chamber. The invention is in particular
based on a synthesis gas passage for diffusion operation in which
by means of swirlers swirl is imparted to the fuel stream by vanes.
The synthesis gas passage in particular takes the form of an
annular space passage and may taper conically downstream.
[0030] The burner may be arranged substantially rotationally
symmetrically about a longitudinal axis, such that a main direction
of flow of the fluid flowing in the passages of the burner points
substantially in the direction of the longitudinal axis (in
particular in the passages arranged radially closer to the
longitudinal axis) or has at least one component in the direction
of the longitudinal axis (in particular in the passages located
radially more to the outside, which upstream may extend initially
substantially diagonally to the longitudinal axis and downstream
follow a course which is approximately parallel to the longitudinal
axis). The air passage and the fuel passage may be arranged
coaxially to one another at least in places, in particular the air
passage may be arranged coaxially around the fuel passage.
[0031] Provision may advantageously also be made for the main
outlet openings of the air passage and fuel passage to be arranged
such that the coaxially surrounding passage is arranged around the
other main outlet opening relative to a projection plane extending
perpendicular to the longitudinal axis.
[0032] This generates flames arranged coaxially to one another from
a common fuel stream with adapted dwell time profile.
[0033] A particularly simple structure is obtained if the air
passage and the fuel passage adjoin one another at least in places
along a wall which substantially takes the form of a cylindrical
casing and/or of a truncated cone-shaped casing, wherein the
connection ducts take the form of holes in the wall.
[0034] According to a particularly advantageous configuration, at
least one adjusting element may be arranged in the region of the
connection ducts, such that the fraction and/or the radial inflow
profile and/or the division over the connection ducts of the fuel
gas branched off from the fuel passage into the air passage is
adjusted and/or adjustable by means of the at least one adjusting
element.
[0035] The adjusting element may influence the static pressure in
the region of the inlet opening of at least one connection duct,
such that a suitable position of the inlet opening is not
exclusively determined by the pressure conditions established in
the fuel passage in the first operating state. In addition, the
adjusting element may be more readily adapted to a desired dwell
time profile (for example by exchange or by modification of the
shape thereof) than the position or size of the at least one
connection duct.
[0036] According to a particularly advantageous configuration of
the adjusting element, a flow guide means is arranged in the fuel
gas passage downstream of at least one fuel passage-side inlet
opening of a connection duct, which flow guide means increases the
static pressure in the region of the inlet openings of the
connection duct when the fuel passage is supplied with fuel
gas.
[0037] It may also be considered advantageous for the flow guide
means to comprise a substantially annular metal plate, wherein the
metal plate is arranged circumferentially on an inside of a wall
delimiting the fuel passage. (The term "metal plate" relates to the
shape, but should not be understood to be limiting for the purposes
of the present invention in respect of the material selected).
[0038] This configuration of the flow guide means has a
particularly simple structure and thus low manufacturing costs.
[0039] To achieve a particularly marked increase in pressure, the
metal plate may extend into the interior of the fuel passage at an
angle contrary to a main direction of flow in the fuel passage. For
example, it may project beyond at least one sub-region of the inlet
openings of the connection ducts.
[0040] To have the least possible effect on the flow profile
between the inlet openings of the connection ducts, the
substantially annular metal plate may in each case have a cut-out
between the regions located downstream of the inlet openings of the
connection ducts, such that the metal plate comprises triangular or
trapezoidal crenellations for example downstream of the inlet
openings.
[0041] Provision may for example be made for the adjusting element
to comprise a number of flow guide means, which take the form of
triangular or trapezoidal metal plates. The triangular metal plates
may be arranged on the inside of the fuel passage similarly to the
above-mentioned substantially annular metal plate. The individual
metal plates certainly have the advantage that no regions of a flow
guide means which disadvantageously increase the pressure drop are
arranged downstream of the regions between the inlet openings.
[0042] An alternative, advantageous configuration of the flow guide
means may comprise at least one cupped element with entry opening,
which is arranged with the entry opening pointing towards the inlet
opening of a connection duct downstream of the inlet opening on an
inside of a wall delimiting the fuel passage.
[0043] The cupped element may advantageously substantially take the
form of a hollow quarter-sphere. This may project at least in part
beyond the inlet opening.
[0044] Provision may further advantageously be made for at least
one adjusting element to be of tubular configuration, wherein the
tubular adjusting element is in each case arranged in particular at
least in part in one of the connection ducts.
[0045] According to a first exemplary embodiment of the
configuration of the invention, the at least one tubular adjusting
element may be partially inserted in each case into a connection
duct and protrude into the air passage, such that the radial
position of the inflow of the branched-off sub-stream flowing
through the respective connection duct may be precisely positioned.
The amount by which the tubular adjusting element protrudes into
the air passage may also vary from tubular adjusting element to
tubular adjusting element depending on the desired radial inflow
profile. According to a further exemplary embodiment of the
configuration of the invention, the at least one tubular adjusting
element may be arranged for example in each case completely in one
connection duct. To adjust the radial inflow profile of the
branched-off fuel stream, the wall thicknesses of the at least one
tubular adjusting element may for example be selected accordingly.
According to a further exemplary embodiment of the invention, the
at least one tubular adjusting element may be fixed to the inside
of the air passage as an extension of a connection duct. According
to a further exemplary embodiment, the at least one tubular
adjusting element may, in addition or as an alternative to the
above-mentioned exemplary embodiments, protrude into the fuel
passage and for example comprise an inflow dish at the end thereof
protruding into the fuel passage. The inflow dish may for example
be configured similarly to the triangular metal plates or the
hollow quarter-spheres. The stated exemplary embodiments of the
tubular adjusting element may for example be combined together or
used individually. If a plurality of such tubular adjusting
elements are provided, these may, depending on the desired radial
inflow profile of the branched-off fuel stream, all be configured
the same or differ from one another, for example in accordance with
the stated exemplary embodiments and combinations thereof.
[0046] A further object of the invention is to provide a method of
the above-stated type which allows an alternative way of reducing
thermoacoustic oscillations in a combustion chamber of a gas
turbine.
[0047] The object is achieved according to the invention for a
method of the above-stated type in that, to adapt the dwell time
profile of a fuel stream flowing in a first fuel passage, a
remaining portion of the fuel stream is introduced into the
combustion chamber through at least one main outlet opening of the
first passage and a branched-off portion of the fuel stream is
introduced, downstream of introduction thereof into the fuel
passage and upstream of the main outlet opening, into at least one
second passage via at least one connection duct, wherein the
branched-off portion of the fuel stream is introduced into the
combustion chamber separately from the remaining fuel stream, such
that the sub-streams, after exit thereof from the burner, are
combusted in the combustion chamber with different dwell times or
dwell time profiles, wherein, to adapt the dwell time profile, the
fraction of the branched-off sub-stream and/or the inflow profile
thereof and/or the division thereof over the at least one
connection duct is adjusted such that fluctuations in heat release
are fed back to a lesser extent into the pressure fluctuations in
the combustion chamber.
[0048] With regard to the possible configurations and advantages of
the method, reference is made to the above explanations relating to
the burner according to the invention.
[0049] Provision may advantageously further be made for the
remaining fuel stream and the branched-off portion of the fuel
stream to be introduced substantially coaxially to one another into
the combustion chamber.
[0050] To adapt the thermoacoustic behavior of the combustion
chamber comprising the burner, the fraction and/or the inflow
profile and/or the division over the at least one connection duct
of the branched-off portion of the fuel stream may be adjusted
prior to start-up of the burner and/or during operation of the
burner.
[0051] Advantageously, adjustment of the fraction and/or the
penetration depth and/or the division over the at least one
connection duct proceeds by adapting at least one flow guide means
arranged in the fuel passage and/or one adjusting element arranged
in the region of the connection ducts.
[0052] According to one advantageous configuration of the
invention, adaptation of the at least one flow guide means and/or
adjusting element may proceed by exchange and/or adaptation of the
shape and/or position thereof.
[0053] A further object of the invention is to provide a combustion
chamber with at least one burner and a gas turbine with at least
one such combustion chamber, which allows an alternative way of
suppressing thermoacoustic oscillations in a combustion chamber of
a gas turbine.
[0054] The object is achieved according to the invention for a
combustion chamber of the above-stated type in that the burner is
configured as claimed.
[0055] The object is achieved according to the invention for a gas
turbine of the above-stated type in that the combustion chamber is
configured as claimed.
[0056] Further convenient configurations and advantages of the
invention constitute the subject matter of the description of
exemplary embodiments of the invention with reference to the
figures of the drawings, wherein the same reference numerals refer
to identically acting components.
BRIEF DESCRIPTION OF THE DRAWINGS
[0057] In the drawings
[0058] FIG. 1 is a schematic representation of a longitudinal
section through a gas turbine according to the prior art, and
[0059] FIG. 2 is a schematic representation of a longitudinal
section through a burner according to the invention according to a
first exemplary embodiment,
[0060] FIG. 3 is a schematic representation of a longitudinal
section through a burner according to the invention according to a
second exemplary embodiment, and
[0061] FIG. 4 is a schematic representation of a longitudinal
section through a burner according to the invention according to a
third exemplary embodiment.
DETAILED DESCRIPTION OF INVENTION
[0062] FIG. 1 shows a schematic sectional view of a gas turbine 1
according to the prior art. In its interior, the gas turbine 1
comprises a rotor 3 mounted so as to rotate about an axis of
rotation 2 and having a shaft 4, said rotor also being known as a
turbine wheel. The following succeed one another along the rotor 3:
an intake housing 6, a compressor 8, a combustion system 9 with a
number of combustion chambers 10, a turbine 14 and a waste gas
housing 15. The combustion chambers 10 each comprise a burner
arrangement 11 and a housing 12, which is lined with a heat shield
20 to provide protection from hot gases.
[0063] The combustion system 9 communicates with a for example
annular hot gas duct. A plurality of series-connected turbine
stages there form the turbine 14. Each turbine stage is formed of
rings of blades or vanes. When viewed in the direction of flow of a
working medium, a row formed of guide vanes 17 is followed by a row
of rotor blades 18 in the hot duct. The guide vanes 17 are here
fastened to an inner housing of a stator 19, whereas the rotor
blades 18 of a row are mounted for example by means of a turbine
disk on the rotor 3. A generator (not shown) is for example coupled
to the rotor 3.
[0064] During operation of the gas turbine, air is drawn in by the
compressor 8 through the intake housing 6 and compressed. The
compressed air provided at the turbine-side end of the compressor 8
is guided to the combustion system 9 and there is mixed with a fuel
in the region of the burner arrangement 11. The mixture is then
combusted in the combustion system 9 with the assistance of the
burner arrangement 11, forming a working gas stream. From there the
working gas stream flows along the hot gas duct past the guide
vanes 17 and the rotor blades 18. At the rotor blades 18 the
working gas stream expands in a pulse-transmitting manner, such
that the rotor blades 18 drive the rotor 3 and the latter drives
the generator (not shown) coupled thereto.
[0065] FIG. 2 is a schematic representation, in longitudinal
section, of a detail of a burner 24 according to the invention for
a gas turbine according to a first exemplary embodiment.
[0066] The burner 24 comprises an air passage 26 in the form of an
annular channel and to which compressed air can be supplied, a fuel
passage 28 configured to be supplied with synthesis gas and a
secondary feed unit 30, which may comprise a pilot burner (not
shown explicitly) and further passages (not shown explicitly) for
introducing a fluid. The burner has a substantially rotationally
symmetrical structure about a longitudinal axis 32. In this
respect, the air passage 26 coaxially encompasses the fuel passage
28 designed for synthesis gas, which in turn coaxially surrounds
the secondary feed unit 30. The secondary feed unit 30 and the two
passages 26 and 28 each respectively comprise a main outlet opening
36, 38, 40 leading into the combustion chamber 34.
[0067] The main outlet opening 36 is here arranged around the main
outlet opening 38 relative to the projection plane 50 extending
perpendicular to the longitudinal axis 32.
[0068] Compressed air entering the air passage 26, the main
direction of flow of which is indicated in the inlet region by an
arrow L'', is swirled by a swirler 42 arranged in the air passage.
The vanes of the swirler extend from an inner wall 44 delimiting
the passage to an outer wall 46 delimiting the passage, wherein the
vanes are arranged in a ring over the circumference of the wall.
The air stream exits the air passage 26 through the main outlet
opening 36. To introduce synthesis gas into the combustion chamber
34, a synthesis gas stream 48 (which may also be premixed with
compressed air prior to entry into the illustrated portion of the
fuel passage 28) is fed to the fuel passage 28 via a feed line
system. The feed line system is not shown in the figure, since it
is located outside the detail illustrated. To swirl the synthesis
gas stream 48, vanes 52 of a swirler are likewise arranged in the
fuel passage 28. Downstream of the vanes 52 the fuel passage 28 and
the air passage 26 are connected fluidically together via
connection ducts 54. In the exemplary embodiment illustrated, the
connection ducts 54 are arranged in a region in which the air
passage 26 and the fuel passage 28 adjoin one another along a wall
56 which substantially takes the form of a cylindrical casing,
wherein the connection ducts 54 are formed as holes in the wall 54
which takes the form of a cylindrical casing.
[0069] The burner 24 is configured such that, in at least one first
operating state of the burner, when air passage 26 is supplied with
compressed air and fuel passage 28 is supplied with fuel gas a
portion of the fuel gas flowing in the fuel passage flows via the
connection ducts 54 into the air passage 26 and, for combustion
thereof, may be introduced through the main outlet opening 36 of
the air passage into the interior of the combustion chamber 34.
[0070] Branching off proceeds such that the common dwell time
profile of the fuel stream prevents or reduces in at least one
frequency band any amplification of thermoacoustic oscillations
which occur in characteristic frequency bands in the respective
combustion chamber 34 of the gas turbine as a function of the power
range. Thus, fluctuations in heat release are fed back to a lesser
extent into the pressure fluctuations in the combustion
chamber.
[0071] The dwell time profile is adapted by means of an adjusting
element 60 to the thermoacoustic behavior of the combustion chamber
34. In the first exemplary embodiment, the adjusting element 60
consists of a flow guide means 62, which is arranged in the fuel
passage 28 downstream of the fuel passage-side inlet openings 64 of
the connection ducts 54 and, on supply of fuel gas to the fuel
passage 28, increases the static pressure in the region of the
inlet openings 64 of the connection ducts 54. The flow guide means
62 takes the form of a substantially annular metal plate 66. This
is arranged circumferentially on the inside 68 of the wall 56
delimiting the fuel passage 28 and extends into the interior of the
fuel passage 28 at an angle contrary to a main direction of flow 70
in the fuel passage. The metal plate 66 here projects, maintaining
a spacing, over at least a sub-region of the inlet openings 64.
Depending on proximity, height, angle of attack and shape of the
metal plate 66, the fraction and/or radial inflow profile and/or
division over the individual connection ducts of the fuel gas
branched off from the fuel passage 28 into the air passage 26 may
be adjusted by means of the at least one adjusting element 60.
[0072] A disadvantageous increase in the pressure drop in the
passage due to the flow guide means may be advantageously reduced
for example by cut-outs (not shown) in the metal plate 66, which
are each arranged between the regions located downstream of the
inlet openings of the connection ducts.
[0073] Segmentation of the metal plate is an even more advantageous
way of preventing a disadvantageous increase in the pressure drop.
The adjusting element 60 may consist of a number of metal plates
each arranged downstream of the inlet openings 64. These may for
example, as illustrated in FIG. 3, take the form of triangular
metal plates 74, which are curved over the inlet openings. For
clarity's sake, only one such metal plate 74 is shown in FIG.
3.
[0074] According to a further exemplary embodiment, which is
illustrated in FIG. 4, the adjusting element 60 may consist of a
row of cupped elements 84, which each comprise an entry opening 86
and are arranged, with this pointing towards the inlet opening 64
of a connection duct 54, downstream of the inlet opening 64 on an
inside 68 of a wall 56 delimiting the fuel passage 28 and in
particular project at least in part beyond the inlet opening 64. In
the exemplary embodiment illustrated in FIG. 4, the cupped element
84 substantially takes the form of a hollow quarter-sphere. FIG. 4
likewise shows for clarity's sake just one such hollow
quarter-sphere.
[0075] The burners 24 according to the invention illustrated in
FIGS. 2 to 4 are suitable for carrying out the method according to
the invention. With reference to FIG. 3, to adapt the dwell time
profile of a fuel gas stream 78 flowing in a fuel passage 28, a
remaining portion 80 of the fuel stream is introduced through at
least one main outlet opening 38 of the fuel passage 28 into the
combustion chamber 34. A branched-off portion 82 of the fuel stream
is introduced, downstream of introduction thereof into the fuel
passage and upstream of the main outlet openings 36 and 38, via the
connection ducts 54 into the air passage 26. The branched-off
portion 82 of the fuel stream is introduced into the combustion
chamber 34 separately from the remaining fuel stream 80, such that
the sub-streams are combusted in the combustion chamber 34 with
different dwell times or dwell time profiles after exiting from the
burner 24, wherein the burner 24 is configured such that the common
dwell time profile of the fuel streams 82 and 80 is adapted via the
fraction of the branched-off sub-stream 82 and/or the inflow
profile thereof and/or division thereof over the at least one
connection duct 54 to the thermoacoustic behavior of the combustion
chamber 34, such that fluctuations in heat release are fed back to
a lesser extent into the pressure fluctuations in the combustion
chamber.
* * * * *