U.S. patent application number 14/934277 was filed with the patent office on 2016-06-02 for helmholtz damper and gas turbine with such a helmholtz damper.
The applicant listed for this patent is ALSTOM Technology Ltd. Invention is credited to Mirko Ruben BOTHIEN, Jost IMFELD, Andre THEUER.
Application Number | 20160153661 14/934277 |
Document ID | / |
Family ID | 51999337 |
Filed Date | 2016-06-02 |
United States Patent
Application |
20160153661 |
Kind Code |
A1 |
BOTHIEN; Mirko Ruben ; et
al. |
June 2, 2016 |
HELMHOLTZ DAMPER AND GAS TURBINE WITH SUCH A HELMHOLTZ DAMPER
Abstract
A Helmholtz damper, especially for damping pulsations in a
combustor of a gas turbine, including a damper volume, which can be
connected to a damped space by means of a neck tube. The Helmholtz
damper further includes a piston, which is moveable within the
damper volume and divides the damper volume into a variable first
part (V1) on one side of said piston. The variable first part (V1)
is connected to the neck tube, and a correspondingly variable
second part (V2) on the other side of said piston. The control
mechanism is substantially simplified in a more compact design by
the piston being driven by a pressure drop (.DELTA.p) between the
first and second part (V1, V2) of the damper volume.
Inventors: |
BOTHIEN; Mirko Ruben;
(Zurich, CH) ; THEUER; Andre; (Baden, CH) ;
IMFELD; Jost; (Scherz, CH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ALSTOM Technology Ltd |
Baden |
|
CH |
|
|
Family ID: |
51999337 |
Appl. No.: |
14/934277 |
Filed: |
November 6, 2015 |
Current U.S.
Class: |
60/725 |
Current CPC
Class: |
F23R 3/16 20130101; F23R
2900/00014 20130101; F23R 2900/00013 20130101; F23R 3/002
20130101 |
International
Class: |
F23R 3/16 20060101
F23R003/16 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 1, 2014 |
EP |
14195660.7 |
Claims
1. A Helmholtz damper, especially for damping pulsations in a
combustor of a gas turbine, comprising a damper volume, which can
be connected to a damped space by means of a neck tube, and further
comprising a piston, which is moveable within said damper volume
and divides said damper volume into a variable first part (V1) on
one side of said piston, which variable first part (V1) is
connected to said neck tube, and a correspondingly variable second
part (V2) on the other side of said piston, wherein said piston is
driven by a pressure drop (.DELTA.p) between said first and second
part (V1, V2) of said damper volume.
2. The Helmholtz damper as claimed in claim 1, wherein the piston
is held in an idle position, where the first part (V1) of said
damper volume is a maximum, by means of a spring, and that said
pressure drop (.DELTA.p) drives said piston against the force of
said spring.
3. The Helmholtz damper as claimed in claim 2, wherein said spring
is arranged within said first part (V1) of said damper volume.
4. The Helmholtz damper as claimed in claim 2, wherein said spring
is arranged outside of said damper volume and acts on said piston
via a piston rod, which extends from said piston to the outside of
said damper volume.
5. The Helmholtz damper as claimed in claim 2, wherein said spring
is a helical spring.
6. The Helmholtz damper as claimed in claim 1, wherein said second
part (V2) of said damper volume is in fluidic connection with the
outside of said damper volume.
7. The Helmholtz damper as claimed in claim 6, wherein said damper
volume is enclosed by a housing, and that said fluidic connection
is established by at least one opening in said housing.
8. A gas turbine comprising a compressor, at least one combustor
and a turbine, whereby said at least one combustor is enclosed by a
combustor casing, the outside of which is exposed to the compressor
outlet pressure (pk2) of said compressor, whereby at least one
Helmholtz damper is provided at and connected to one combustor in
order to damp pulsations within said combustor, wherein said at
least one Helmholtz damper is a Helmholtz damper as claimed in
claim 1, and that a pressure drop between said compressor outlet
pressure (pk2) and the pressure within said combustor is used to
drive said piston of said at least one Helmholtz damper.
9. The gas turbine as claimed in claim 8, wherein said at least one
Helmholtz damper is attached to said combustor casing by adaptation
means.
10. The gas turbine as claimed in claim 9, wherein said at least
one Helmholtz damper is connected to said combustor through a hole
in said combustor casing, and that said adaptation means comprises
an insert, which fits into said hole and receives a neck tube of
said at least one Helmholtz damper such that said neck tube passes
through said insert to open out into said combustor.
11. The gas turbine as claimed in claim 10, further comprising a
neck tube adapter is provided to seal said neck tube against said
insert.
12. The gas turbine as claimed in claim 10, wherein said neck tube
is releasably connected to the damper volume of said at least one
Helmholtz damper.
13. The gas turbine as claimed in claim 8, wherein said combustor
is of an annular configuration, and that a plurality of Helmholtz
dampers are circumferentially arranged around said combustor.
14. The gas turbine as claimed in claim 8, wherein said at least
one combustor is of the can type, and that the Helmholtz damper is
circumferentially arranged around the can combustor.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to EP Application No.
14194660.7 filed Dec. 1, 2014, the contents of which are hereby
incorporated in its entirety.
TECHNICAL FIELD
[0002] The present invention relates to the field of combustion
technology. It refers to a Helmholtz damper according to the
preamble of claim 1.
[0003] It further refers to a gas turbine with such a Helmholtz
damper.
BACKGROUND
[0004] FIG. 1 shows in a perspective view an exemplary stationary
or industrial gas turbine of the GT13 E2 type. The gas turbine 10
comprises in a casing 13 a rotor 12, which rotates around a machine
axis and defines within the casing 13 an annular hot gas channel
extending in axial direction through the machine. A compressor 14
with several stages of running blades compresses air, which enters
the machine through an air inlet 11. The compressed air with a
compressor outlet pressure pk2 fills a plenum and enters a
combustor 15, where it is mixed with a fuel supplied by a plurality
of burners 16. In this case, the burners 16 are configured as
so-called AEV (or Advanced Environmental Vortex) burners, which are
described for example in document WO 2009/109454.
[0005] FIG. 2 shows the main parameters of a generic Helmholtz
damper configuration. The Helmholtz damper 20 of FIG. 2 comprises a
damper volume 21 with a volume V, which is in fluidic connection
with a damped space (combustor) 19 via a neck tube 22 of length
L.sub.N and inner diameter D.sub.N; u denotes the bias mean flow.
The resonance frequency f of this damper can be approximately
calculated by the formula:
f .apprxeq. c 2 .pi. A N V ( L N + dL N ) ##EQU00001##
with the speed of sound c, and the area A.sub.N and length L.sub.N
of neck tube 22.
[0006] This means, that
f ~ 1 V . ##EQU00002##
[0007] When Helmholtz damper 20 is attached to the combustor 15 of
gas turbine 10 of FIG. 1, it is surrounded by the plenum of the gas
turbine, which is filled with compressed air of compressor outlet
pressure pk2. Cooling air is introduced into damper volume 21
through an orifice 23, which experiences a pressure drop .DELTA.p
due to the difference between the (higher) compressor outlet
pressure pk2 and the (lower) pressure within the combustion chamber
of the combustor.
[0008] Further, it is known that the frequency of the pulsations
within the combustor depends on the operation mode of the gas
turbine. Especially, there is a change in pulsation frequency
f.sub.P, when the gas turbine changes from part load operation to
base load operation, and vice versa. For a gas turbine of the type
shown in FIG. 1 there can be a change of up to 20% of pulsation
frequency f.sub.P between part load and base load, with the
pulsation frequency increasing with growing load.
[0009] To maintain the maximum damping properties of Helmholtz
dampers used with such gas turbine, the resonance frequency of the
dampers should stay tuned to the pulsation frequency even if the
load conditions of the gas turbine change. According to the formula
given above, the damper volume V should be changed in accordance
with a change in the load conditions.
[0010] In the prior art, there are solutions described on closed
loop volume adjustments in Helmholtz dampers by moving pistons.
This, however, is not a solution for an actual engine due to high
costs of control device (loop), stepping motor, and manufacturing
tolerance of piston.
[0011] Another existing solution is to simply place more dampers
that are tuned to different frequencies.
[0012] Some of the known solutions are cited below:
[0013] Document EP 2 397 761 A1 discloses a Helmholtz damper and a
method for regulating the resonance frequency of a Helmholtz
damper. In particular, it refers to Helmholtz dampers to be
connected to lean premixed, low emission combustion systems of gas
turbines, whereby said Helmholtz damper comprises an enclosure from
which a neck extends, and a pipe is inserted into and fits the
neck. Especially, an actuator is connected to the pipe to adjust
its portion inserted into the neck.
[0014] Document EP 2 397 760 A1 discloses a damper arrangement that
has a first Helmholtz damper connected in series to a second
Helmholtz damper. The resonance frequency of the first Helmholtz
damper and the resonance frequency of the second Helmholtz damper
are shifted from one another in an amount producing a synergic
damping effect.
[0015] Document DE 100 26 121 A1 describes an apparatus for damping
acoustic vibrations in a combustor as well as a corresponding
combustor arrangement with the apparatus. The apparatus comprises a
Helmholtz resonator that can be connected via a connecting channel
with a combustor. The Helmholtz resonator contains a hollow body
the volume of which can be changed by adding or draining a fluid
via a supply line, or is located adjacent to such a hollow body in
such a way that the resonance volume of the Helmholtz resonator is
changed when the volume of the hollow body is changed. This
apparatus makes it possible to adjust the resonance frequency of a
Helmholtz resonator arranged inside a pressure container in
accordance with the respective current operating point of the
combustor to be damped, without having to pass movable components
through the pressure container.
[0016] Document U.S. Pat. No. 8,661,822 B2 discloses a system with
a turbine engine, comprising: a compressor; a turbine; a combustor
disposed downstream from the compressor and upstream from the
turbine; a fluid injection system configured to inject one or more
fluids into the combustor; a variable geometry resonator coupled to
the fluid injection system; and a controller configured to tune the
variable geometry resonator in response to feedback.
[0017] However, the problem with all these solutions is that they
increase costs on the one hand and often are not possible at all to
apply due to limited space to put dampers inside an engine.
SUMMARY
[0018] It is an object of the present invention to provide a
Helmholtz damper, which is simple in construction, requires minimum
space and has a self-adjusting capability.
[0019] It is another object of the invention to provide a Helmholtz
damper with a design that allows an adjustment of the damper volume
in a way that is applicable to the combustor environment inside an
engine and fulfils requirements of robustness and costs.
[0020] It is a further object of the invention to provide a gas
turbine with such a Helmholtz damper.
[0021] These and other objects are obtained by a Helmholtz damper
according to Claim 1 and a gas turbine according to Claim 8.
[0022] The Helmholtz damper according to the invention, which is
especially suitable for damping pulsations in a combustor of a gas
turbine, comprises a damper volume, which can be connected to a
damped space by means of a neck tube, and further comprises a
piston, which is moveable within said damper volume and divides
said damper volume into a variable first part on one side of said
piston, which variable first part is connected to said neck tube,
and a correspondingly variable second part on the other side of
said piston. It is characterized in that said piston is driven by a
pressure drop between said first and second part of said damper
volume.
[0023] An embodiment of the Helmholtz damper according to the
invention is characterized in that the piston is held in an idle
position, where the first part of said damper volume is a maximum,
by means of a spring, and that said pressure drop drives said
piston against the force of said spring.
[0024] Specifically, said spring is arranged within said first part
of said damper volume.
[0025] Alternatively, said spring may be arranged outside of said
damper volume and acts on said piston via a piston rod, which
extends from said piston to the outside of said damper volume.
[0026] Specifically, said spring is a helical spring.
[0027] Another embodiment of the Helmholtz damper according to the
invention is characterized in that said second part of said damper
volume is in fluidic connection with the outside of said damper
volume.
[0028] Specifically, said damper volume is enclosed by a housing,
and said fluidic connection is established by at least one opening
in said housing.
[0029] The gas turbine according to the invention comprises a
compressor, at least one combustor and a turbine, whereby said at
least one combustor is enclosed by a combustor casing, the outside
of which is exposed to the compressor outlet pressure of said
compressor, whereby at least one Helmholtz damper is provided at
and connected to one combustor in order to damp pulsations within
said combustor. It is characterized in that said at least one
Helmholtz damper is a Helmholtz damper according to the invention,
and that a pressure drop between said compressor outlet pressure
and the pressure within said combustor is used to drive said piston
of said at least one Helmholtz damper.
[0030] An embodiment of the gas turbine according to the invention
is characterized in that said at least one Helmholtz damper is
attached to the combustor casing by adaptation means.
[0031] Specifically, said at least one Helmholtz damper is
connected to said combustor through a hole in said combustor
casing, and said adaptation means comprises an insert, which fits
into said hole and receives a neck tube of said at least one
Helmholtz damper such that said neck tube passes through said
insert to open out into said combustor.
[0032] More specifically, a neck tube adapter is provided to seal
said neck tube against said insert.
[0033] Especially, said neck tube is releasably connected to the
damper volume of said at least one Helmholtz damper.
[0034] Another embodiment of the gas turbine according to the
invention is characterized in that said combustor is of an annular
configuration, and that a plurality of Helmholtz dampers are
circumferentially arranged around said combustor.
BRIEF DESCRIPTION OF THE DRAWINGS
[0035] The present invention is now to be explained more closely by
means of different embodiments and with reference to the attached
drawings.
[0036] FIG. 1 shows in a perspective view a stationary gas turbine
of the GT13 E2 type, which is suitable for being used with
Helmholtz dampers according to the invention;
[0037] FIG. 2 shows the main parameters of a basic Helmholtz damper
configuration;
[0038] FIG. 3 shows an example of the absolute pressure drop
.DELTA.p as a function of relative gas turbine load for an
exemplary gas turbine;
[0039] FIG. 4 shows an embodiment of the Helmholtz damper according
to the invention with the piston (a) in a starting position and (b)
in an active position driven by a certain pressure drop
.DELTA.p;
[0040] FIG. 5 shows a Helmholtz damper according to another
embodiment of the invention attached and coupled to the combustor
of a gas turbine of the type shown in FIG. 1; and
[0041] FIG. 6 shows (a) in detail the Helmholtz damper of FIG. 5
and (b) in even more detail the piston of said damper;
[0042] FIG. 7 shows a Helmholtz damper according to a further
embodiment of the invention attached and coupled to a can
combustor.
DETAILED DESCRIPTION
[0043] As has been said before, the pulsation frequency in gas
turbine combustors usually increases with relative load. A damper
that is optimized for part load operation consequently does not
exhibit its maximum damping performance at base load and vice
versa.
[0044] The idea of this invention is to make use of the relative
pressure drop .DELTA.p between compressor plenum and combustion
chamber that also increases with relative load RL.sub.GT. FIG. 3
shows the results of measurements of the absolute pressure drop
.DELTA.p as a function of relative gas turbine load for an
exemplary gas turbine.
[0045] The invention seeks to explore this fact in such a way that
the volume V of the damper is reduced so that its resonance
frequency is continuously adjusted in order to provide highest
damping at the required frequency. This is possible due to the fact
that the outside of the damper volume is exposed the compressor
outlet pressure pk2, whereas the pressure inside the damper is very
close to that of the combustion chamber.
[0046] FIG. 4 shows an embodiment of the Helmholtz damper according
to the invention. In FIG. 4(a) shows the damper in a starting
position with its damper volume being a maximum. FIG. 4(b) shows
the damper in an active position, wherein the damper volume has
been automatically reduced due to an increased pressure drop
.DELTA.p between inside and outside of the damper.
[0047] The Helmholtz damper 24 according to FIG. 4 comprises damper
volume 25, which is enclosed by a housing 25a. The damper volume 25
is divided by means of a piston 27 which is moveable within said
damper volume 25, into a variable first part V1 on one side of the
piston 27, and a correspondingly variable second part V2 on the
other side of said piston 27. The variable first part V1 is
connected to a neck tube 26 of said Helmholtz damper 24. The
variable second part V2 is connected to the outside of Helmholtz
damper 24 by means of openings 31 provided in housing 25a. In this
way, combustor pressure p.sub.C acts through neck tube 26 on one
side of piston 27 with area A2, while compressor outlet pressure
pk2 acts through openings 31 on the other side of piston 27 with
area A1, such that a pressure drop .DELTA.p=pk2-p.sub.C exists
across piston 27. An orifice 32 may be provided through piston 27
to allow the access of some cooling air.
[0048] When Helmholtz damper 24 is in its starting position (FIG.
4(a)), the volume is defined by diameter D or area A1 and height
H1. When piston 27 has been moved a distance .DELTA.H due to an
associated pressure drop .DELTA.p (FIG. 4(b)), the damper volume
(V1) has been decreased to A2.times.H2. The driving force of
pressure drop .DELTA.p on piston 27 is balanced by the spring force
of a helical spring 30, which is in this case arranged outside the
damper volume and is compressed, when piston 27 leaves its starting
position. The spring 30 is arranged between the top of housing 25a
and a bearing plate 29 at the end of a piston rod 28, which extends
from piston 27 to the outside of damper volume 25 and serves to
couple the balancing spring force to piston 27.
[0049] A more compact design of a Helmholtz damper according to the
invention, which is more suitable for being applied to a gas
turbine combustor 33, is shown in FIGS. 5 and 6.
[0050] Helmholtz damper 38 of FIGS. 5 and 6 is attached to
combustor casing 34 at a place, where the hot gas 39 is guided to
combustor outlet 35. Helmholtz damper 38 comprises a damper volume
40 enclosed by a housing 40a, and divided by a piston 44. Housing
40a is on its upper side in fluidic connection with the environment
(plenum pressure pk2) by means of a wide opening 46. At its lower
side, it is closed by a bowl-like base element 41. A separate neck
tube 43, which extends from the combustion chamber into the
interior of damper volume 40, connects the damper volume with the
combustor. Neck tube 43 is fixed in a neck tube adapter 42, which
is held between base element 41 and an insert 37 that is used to
mount the damper arrangement in a hole 36 in the combustor casing
34. The neck tube 43 may be of any cross-sectional shape.
[0051] Piston 44, which has an orifice 47 for cooling purposes, is
designed as a free piston. A balancing helical spring 45 is
arranged within the damper volume 40. This configuration with a
free piston and an internal balancing spring is on one hand very
compact, requiring only minimal space, and on the other hand is
protected against impacts from outside.
[0052] The embodiment of FIG. 7 schematically illustrates a
Helmholtz damper 48 attached to a can combustor 49. Arrow 39
represents the hot gas flow. The damper 48 is circumferentially
arranged around the can combustor 49, forming an annular damper
volume 40, surrounding the combustion chamber or hot gas path
respectively. At least one neck tube 43 of any cross-sectional
design connects the space 19, to be damped, with the variable first
part V1 of the damper volume 40. At least one opening 46 connects
the variable second volume V2 with an environment outside of the
Helmholtz damper 48. The variable first part V1 of the damper
volume 40 and the variable second part V2 of the damper volume 40
are separated by the piston 44. The piston 44 is arranged and
designed to perform a movement parallel to the axis of the
combustor 49, thereby interacting with the balancing spring 45 of
the helical type, arranged within the damper volume 40 along the
lateral surface area of the damper housing 40a.
* * * * *