U.S. patent application number 14/522994 was filed with the patent office on 2015-04-30 for damping device for a combustor of a gas turbine.
The applicant listed for this patent is ALSTOM Technology Ltd. Invention is credited to Mirko Ruben Bothien, Devis TONON.
Application Number | 20150113991 14/522994 |
Document ID | / |
Family ID | 49485608 |
Filed Date | 2015-04-30 |
United States Patent
Application |
20150113991 |
Kind Code |
A1 |
TONON; Devis ; et
al. |
April 30, 2015 |
DAMPING DEVICE FOR A COMBUSTOR OF A GAS TURBINE
Abstract
The present invention relates to a damping device for a
combustor of a gas turbine for suppressing combustion
instabilities. More specifically, the invention relates to a design
of a broadband damping device for a low emission combustor having
at least one resonator for damping pressure fluctuations in the
combustion chamber. It is an object of the invention to provide a
damping device with a quarter wave damper having broadband
characteristics. The damping device for a combustor of a gas
turbine according to the invention comprises a casing defining a
resonator volume, a hole at a front face of the casing for allowing
fluid communication between the resonator volume and the combustion
chamber, the casing having parameters such that it acts as a
quarter wave damper, is characterized in that the resonator volume
is limited by a rear face and at least one lateral surface of the
casing, whereby at least one lateral surface is equipped with one
or more cavities inside and the rear face is equipped with at least
one feed hole for feeding a purging fluid into the resonator
volume. The preferably groove-shaped side cavities initiate energy
dissipating vertical flows.
Inventors: |
TONON; Devis; (Turgi,
CH) ; Bothien; Mirko Ruben; (Zurich, CH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ALSTOM Technology Ltd |
Baden |
|
CH |
|
|
Family ID: |
49485608 |
Appl. No.: |
14/522994 |
Filed: |
October 24, 2014 |
Current U.S.
Class: |
60/725 |
Current CPC
Class: |
F23R 3/002 20130101;
F23M 20/005 20150115; F23R 3/02 20130101; F23R 2900/00014 20130101;
F01N 1/023 20130101 |
Class at
Publication: |
60/725 |
International
Class: |
F23M 23/20 20060101
F23M023/20; F23R 3/00 20060101 F23R003/00 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 25, 2013 |
EP |
13190333.8 |
Claims
1. A damping device for a combustor of a gas turbine for
suppressing combustion instabilities in a combustion chamber,
comprising a liner extending from an upstream end downwardly around
the combustion chamber, at least one acoustic damper provided along
the liner and/or a supply line for fuel or air to the combustion
chamber, the acoustic damper comprising a casing defining a
resonator volume, a hole at a front face of the casing for allowing
fluid communication between the resonator volume and the combustion
chamber, the casing having parameters such that it acts as a
quarter wave damper, wherein the resonator volume is limited by a
rear face and at least one lateral surface of the casing, whereby
at least one lateral surface is equipped with one or more cavities
and the rear face is equipped with at least one feed hole for
feeding a purging fluid into the resonator volume.
2. The damping device according to claim 1, wherein at least one of
the cavities is groove-shaped.
3. The damping device according to claim 2, wherein at least one
cavity runs circumferentially around the lateral surface.
4. The damping device according to claim 3, wherein two or more
rows of circumferentially running cavities are arranged
consecutively in a longitudinal direction of the casing.
5. The damping device according to claim 2, wherein the casing is
equipped with at least one corrugated lateral surface.
6. The damping device according to claim 1, wherein the casing is a
tube.
7. The damping device according to claim 1, wherein the casing has
a circular or elliptic cross section.
8. The damping device according to claim 1, wherein the casing has
a polygonal, particularly rectangular cross section.
9. The damping device according to claim 8, further comprising at
least a first lateral surface equipped with one or more side
cavities, whereas at least a second lateral surface is even.
10. The damping device according to claim 1, further comprising a
longitudinal axis of the damper casing possesses an orientation
orthogonally or essentially orthogonally to the outer surface of
the combustor liner.
11. The damping device according to claim 1, wherein the
longitudinal axis of the damper casing possesses an inclined
orientation to the outer surface of the combustor liner.
12. The damping device according to claim 1, wherein the
longitudinal axis of the damper casing is arranged parallel to the
outer surface of the liner.
13. The damping device according to claim 1, wherein the quarter
wave damper is coupled to an air supply line.
14. The damping device according to claim 1, wherein the quarter
wave damper is coupled to a can combustor.
15. The damping device according to claim 1, wherein the quarter
wave damper is coupled to an annular combustion chamber.
16. A combustor for a gas turbine, disposed downstream from a
compressor and upstream from a turbine, said combustor comprising
at least one burner at an upstream end, configured to inject a fuel
and/or air or a fuel/air mixture into a combustion chamber, a liner
extending from the upstream end downwardly around the combustion
chamber, wherein the combustor additionally comprises at least one
quarter wave damper according to claim 1 for suppressing combustion
instabilities in the combustion chamber.
17. The combustor according to claim 16, further comprising at
least two quarter wave dampers disposed circumferentially around
the combustor liner.
18. The combustor according to claim 16, further comprising at
least two quarter wave dampers disposed in different longitudinal
positions of the combustor.
19. The combustor according to claim 16, wherein at least one of
the quarter wave dampers is folded around the combustor liner.
20. The combustor according to claim 19, wherein at least one of
the dampers is folded in circumferential direction with respect to
the combustor liner.
21. The combustor according to claim 19, wherein at least one of
the dampers is folded in longitudinal direction with respect to the
combustor liner.
22. The combustor according to claim 16, wherein the combustor is a
can combustor of a stationary gas turbine.
23. The combustor according to claim 16, wherein the combustor is
an annular combustion chamber of a stationary gas turbine.
24. The combustor according to claim 16, further comprising a
number of quarter wave dampers of different geometry is coupled to
the liner.
25. The combustor according to claim 24, further comprising quarter
wave dampers of different lengths are coupled to the liner.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to European application
13190333.8 filed Oct. 25, 2013, the contents of which are hereby
incorporated in its entirety.
TECHNICAL FIELD
[0002] The present invention relates to a damping device for a
combustor of a gas turbine. More specifically, the invention
relates to a design of a broadband damping device for a low
emission combustor having at least one resonator for damping
pressure fluctuations in the combustion chamber.
BACKGROUND
[0003] Gas turbines are known to comprise at least one combustor,
wherein a fuel and air are combusted to generate high pressure hot
combustion gases that are expanded in a turbine performing work. In
general, the combustion may occur either in a number of combustors
circumferentially positioned around a longitudinal axis of the gas
turbine or in an annular combustion chamber with a number of
burners at its upstream end.
[0004] During operation of the combustor significant pressure
oscillations at various frequencies may occur. If one of these
frequencies corresponds to an eigen frequency of a component or a
system structural damages to the components of the gas turbine
plant may result limiting its operating regime.
[0005] For the attenuation of combustion dynamics, gas turbine
combustors are usually provided with damping devices, in particular
Helmholtz resonators, to damp pressure oscillations.
[0006] Helmholtz resonators are widely used in this technical
field. Their use is disclosed in many prior art publications.
Usually a plurality of resonators is coupled to the combustor at
its upstream end and/or downstream at its liner in flow
communication with the interior of the combustor.
[0007] A drawback of conventional Helmholtz resonators is the
required space. Helmholtz dampers require a relatively high volume,
but the available space in the region surrounding the combustor is
often limited. A consequence are design constraints to install such
damping devices. Another significant design consideration is the
component weight, Helmholtz resonators are relatively heavy.
[0008] EP 2402658 discloses a combustor with lean combustion and
low emissions for a gas turbine that requires a small mounting
space for an acoustic damper that can achieve size reduction. In
order to achieve this aim, according to a first aspect the
combustor comprises an acoustic damper that includes an acoustic
damper resonance space communicating with the inner combustion
chamber. The acoustic damper is provided along a combustor housing
extending in a direction intersecting an axial direction of the
combustor. Because the damper is provided along the housing so as
to extend in a direction intersecting the axial direction of the
combustor, the acoustic damping device is disposed widely in the
circumferential direction, without concentrating in a particular
section of the combustor in its circumferential direction. As a
result, the damping device is prevented from protruding toward the
outer circumference of the housing, and the space needed outside
the combustor can be reduced.
[0009] A different approach for damping pressure oscillations
caused by combustion dynamics is the application of quarter wave
dampers. A quarter wave damper includes a resonator tube of a
defined length L. A quarter wave damper is tuned to a quarter of
the wavelength of an acoustical oscillation. The resonant frequency
of a quarter wave damper is
f=c.sub.0/4L,
wherein c.sub.0 is the speed of sound in the resonator tube and L
is the length of the resonator tube.
[0010] Consequently a quarter wavelength damper may absorb a
frequency corresponding to a wavelength four times the tube length
L.
[0011] FIG. 1 shows in a rough schematic manner the main features
of a quarter wave damper 2 connected to a combustor or a supply
line for fuel or air to a combustion chamber. The damper 2 includes
a casing 3, usually designed as a tube, fixed to the combustor
liner 4 or the fuel or air supply line, the tube 3 having a length
5 and defining a resonator volume 6. Via an opening 7 at its front
face the resonator volume 6 is in flow communication with the
combustion chamber 8 in which the pressure oscillations, to be
damped, may occur. The damper parameter that mainly defines the
damped frequency is the tube length 5. Consequently, these
geometrical features have to be determined in accordance with the
combustion dynamics of the combustor.
[0012] An essential feature of the quarter wave dampers according
to the state of the art is that they provide high damping
performances, but only in a narrow frequency band that lies around
the resonance frequency of the damper. This behavior is a
fundamental disadvantage for a use in gas turbine combustors.
[0013] The frequency of pressure oscillations may slightly change
from gas turbine to gas turbine and, in addition, also for the same
gas turbine it may slightly change as a function of variations of
the operating conditions (for example part load, base load,
transition). If narrow band dampers are adopted, each of these
frequency shifts will result in a rise of pulsations.
SUMMARY
[0014] Therefore, it is the technical aim of the present invention
to avoid the above-mentioned disadvantages by providing a damping
device with a quarter wave damper having broadband characteristics
and by providing a combustor equipped with such a damping
device.
[0015] According to a first aspect of this invention this aim is
achieved by a damping device according to claim 1.
[0016] According to a second aspect of this invention this aim is
achieved by a combustor according to claim 16.
[0017] Preferred embodiments of these inventive aspects are subject
of the respective dependent claims.
[0018] More specifically, it is the basic idea of this invention to
provide a quarter wave damper with a modified new design, the
quarter wave damper comprising a casing, particularly a tubular
casing, defining a resonator volume, a hole at a front face of this
casing for allowing fluid communication between the resonator
volume and the combustion chamber, a rear face with at least one
feed hole for feeding a purging fluid into the resonator volume and
at least one lateral surface, whereby this lateral surface is
equipped with one or more side cavities inside.
[0019] The feeding hole at the rear face and the hole at the front
face define a flow path across the resonator volume inside the
quarter wave damper.
[0020] According to a preferred embodiment the at least one side
cavity is groove-shaped and runs circumferentially around the
lateral surface of the casing.
[0021] In particular, the lateral surface of the damper casing is
equipped with two or more circumferential cavities, arranged in a
number of rows along the casing between its rear end and its front
end.
[0022] This design is preferably applicable for quarter wave
dampers with a circular cross section.
[0023] According to an alternative embodiment, preferably
applicable to quarter wave dampers with a polygonal, especially
rectangular cross section, the provision of side cavities is
limited to one side. A first lateral surface of the e.g.
rectangular damper is equipped with a number of consecutively
arranged side cavities; whereas a second lateral surface, e.g. the
opposite surface, is even. Preferably the side cavities extend over
the whole width of the said first lateral surface.
[0024] During operation of the combustor a mass flow of a purging
fluid, preferably purging air, passes the resonator volume from the
feed opening at the rear face towards the front face and exits the
resonator volume through the opening there into the combustion
chamber. The side cavities in the lateral surface, arranged
orthogonally or at least essentially orthogonally to the mass flow
of the purging fluid, cause flow disturbances. Vortical flows are
initiated at each cavity. The formed shear layers roll up, thereby
interacting with existing and new shear layers and vortices in a
complex interaction. These energy dissipating processes absorb
acoustic power.
[0025] One parameter for controlling the damping quality of a
certain damper configuration is the flow velocity of the mass flow
of purging fluid through the resonator volume. The damping quality
of the damper during operation can be changed by varying the flow
velocity.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] Further characteristics and advantages of the invention will
be more apparent from the description of preferred embodiments of
the invention, illustrated by way of non-limiting examples in the
accompanying drawings, in which:
[0027] FIG. 1 is a rough schematic view showing the principle
features of a damping device, comprising a quarter wave damper
coupled to a combustor;
[0028] FIG. 2 shows in a similar view a damping device with a
quarter wave damper, modified according to the invention;
[0029] FIG. 2a shows a detail of FIG. 2;
[0030] FIGS. 3a and 3b show, in addition to FIG. 2, alternative
designs of a quarter wave damper according to the invention;
[0031] FIGS. 4a and 4b show two alternative embodiments of
arranging quarter wave dampers around a combustor.
DETAILED DESCRIPTION
[0032] FIG. 1 shows in a rough schematic manner the main features
of a quarter wave damper 2 coupled to the liner 4 of a combustor 1
or a supply line of the fluid injection system according to the
state of the art. The quarter wave damper 2 includes a casing 3,
usually designed as a tube, fixed to the combustor liner 4. The
tubular casing 3, having a longitudinal axis 15, a front face with
an opening 7, a rear end face 11 and a lateral surface 14, defines
a resonator volume 6. Via an opening 7 at its front face the
resonator volume 6 is in flow communication with the combustion
chamber 8 in which the pressure oscillations, to be damped, occur.
The distance between the front face with opening 7 and the rear end
face 11 defines the length 5 of the quarter wave damper 2. The
damper parameter that mainly defines the damped frequency is its
length 5. Consequently, these geometrical features have to be
determined in accordance with the combustion dynamics of the
combustor. As the name implies, the quarter wave damper 2 is tuned
to a quarter of the wavelength of the relevant acoustical
oscillations in the combustion chamber 8. The resonant frequency is
f=c.sub.0/4L, wherein c.sub.0 is the speed of sound in the
resonator volume 6 and L is the length 5 of its tubular casing
3.
[0033] It is known per se to couple a number of quarter wave
dampers 2 with different lengths 5 to a combustor 1, e.g. two
different lengths, to damp oscillations of different frequencies,
particularly to damp two dominant frequencies.
[0034] FIG. 2 shows in a similar view a damping device with a
modified quarter wave damper 2 in accordance with the invention.
The combustion chamber 8 is enclosed by the liner 4 of the
combustor 1. The modified quarter wave damper 2 is coupled to said
liner 4 in a manner, known per se. The quarter wave damper 2
comprises an essentially cylindrical casing 3 with an opening 7 at
its front face, a lateral surface 14 and a rear end 11. The opening
7 at the front face enables flow communication between the
combustion chamber 8 and the resonator volume 6 inside the casing
3. The lateral surface 14 of the casing 3 is equipped with at least
one cavity 9. This cavity 9 may run circumferentially around the
inner lateral surface 14. As shown in FIG. 2, a number of rows of
circumferentially running cavities 9 may be arranged along the
lateral surface between the front end and the rear end of the
casing 3.
[0035] In addition, the rear end 11 of the damper 2 is equipped
with an opening 10 for feeding a purging fluid, usually air, into
the resonator volume 6. During operation of the combustor 1 a mass
flow 12 of purging air is flowing through the resonator volume 6
from the opening 10 at the rear face 11 towards the front face and
exits the resonator volume 6 through the opening 7 into the
combustion chamber 8.
[0036] The groove-shaped cavities 9 in the lateral surface 14 cause
flow disturbances, as shown in FIG. 2a. When passing the edges of
the side cavities 9 vertical flows 13 are initiated at each cavity
9. The shear layers, formed in the velocity-gradient region, roll
up into a spiral, thereby interacting with existing and new shear
layers and vortices in a complex interaction. As a consequence
these energy dissipating processes absorb acoustic power.
[0037] The structural parameters of the damper and the flow
velocity are defined in order to damp at the desired frequency. It
applies the equation
U = f 0 W eff 0.39 ##EQU00001##
wherein U is the flow velocity through the damper, f.sub.0 is the
frequency to damp, W.sub.eff stands for the effective width of the
cavity 9 and the divisor 0.39 represents the optimal Strouhal
number.
[0038] FIGS. 3a and 3b show in an exemplary manner different
geometrical options of a modified quarter wave damper 2 according
to the invention.
[0039] FIG. 3a depicts a corrugated damper 2. At least one lateral
surface 14 of the casing 3 is provided with a corrugated design.
Preferably the cross section of a quarter wave damper 2 according
to this design is circular. In this case the casing 3 is made of a
corrugated tube from a suitable material.
[0040] Alternatively a rectangular cross section can be provided.
In that case two opposite lateral surfaces 14 are provided with a
corrugated design.
[0041] The corrugation is disposed orthogonally to the direction of
the mass flow 12 of purging air. When passing the individual
corrugations, a respective vortice flow is formed at each cavity
9.
[0042] FIG. 3b depicts an alternative embodiment, a side branched
quarter wave damper. The provision of side cavities 9 is limited to
one of the longitudinal sides. This design may preferably be used
for dampers 2 with a rectangular cross section. One lateral surface
14' of the rectangular damper is equipped with a number of
consecutively arranged side cavities 9, whereas the opposite
surface 14'' is even. Preferably, the side cavities 9 extend over
the whole width of the surface 14'.
[0043] The FIGS. 4a and 4b show in a rough schematic manner two
basic options regarding the application of a damping device
according to the invention to a can combustor of a gas turbine.
[0044] For the purpose of reducing the required space outside the
combustor 1 the quarter wave dampers 2 have to be prevented from
protruding toward the outer circumference of the combustor 1.
[0045] This is achieved by arranging the individual quarter wave
dampers 2 around the combustor in such a way that the longitudinal
axes 15 of the quarter wave dampers 3 are inclined or parallel to
the surface of the liner 4.
[0046] The two basic options comprise an arrangement around the
combustion chamber in circumferential direction or in longitudinal
direction. A number of quarter wave dampers 2 is folded around the
combustor 1 of the gas turbine. This means, the longitudinal axis
15 of the applied dampers 2 is arranged parallel or essentially
parallel to the outer surface of the liner 4.
[0047] According to the first option (FIG. 4a) the longitudinal
axis 15 of the dampers 2 is in line with the circumferential
direction of the combustor 1. A number of dampers 2 is coupled to
the liner 4 in different axial positions of the combustor 1.
[0048] According to the second option (FIG. 4b) the longitudinal
axis of the dampers 2 is in line with the longitudinal axis of the
combustor 1. A number of dampers 2 is coupled to the liner around
the circumference of the combustor at essentially the same axial
position.
[0049] As indicated by the figures, both options offer the
possibility of applying quarter wave dampers 2 of different lengths
to damp more than one dominant frequency.
* * * * *