U.S. patent application number 13/807036 was filed with the patent office on 2013-09-12 for burner for a gas combustor and a method of operating the burner thereof.
The applicant listed for this patent is Robert W. Dawson, Peter Kaufmann, Jaap Van Kampen. Invention is credited to Robert W. Dawson, Peter Kaufmann, Jaap Van Kampen.
Application Number | 20130232988 13/807036 |
Document ID | / |
Family ID | 44628540 |
Filed Date | 2013-09-12 |
United States Patent
Application |
20130232988 |
Kind Code |
A1 |
Dawson; Robert W. ; et
al. |
September 12, 2013 |
BURNER FOR A GAS COMBUSTOR AND A METHOD OF OPERATING THE BURNER
THEREOF
Abstract
A burner for a gas combustor and a method of operating the
burner are disclosed. The burner includes a front surface area
divided into a plurality of subareas and inlets arranged on the
front surface area such that each subarea is encircled by at least
four inlets and such that during operation of the burner, a gas
recirculation in the combustor is facilitated corresponding to each
subarea.
Inventors: |
Dawson; Robert W.; (Oviedo,
FL) ; Kaufmann; Peter; (Moers, DE) ; Van
Kampen; Jaap; (Roermond, NL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Dawson; Robert W.
Kaufmann; Peter
Van Kampen; Jaap |
Oviedo
Moers
Roermond |
FL |
US
DE
NL |
|
|
Family ID: |
44628540 |
Appl. No.: |
13/807036 |
Filed: |
July 13, 2011 |
PCT Filed: |
July 13, 2011 |
PCT NO: |
PCT/EP11/61909 |
371 Date: |
May 28, 2013 |
Current U.S.
Class: |
60/776 ;
60/746 |
Current CPC
Class: |
F23R 3/28 20130101; F23R
3/346 20130101; F23R 2900/00015 20130101; F23R 3/343 20130101; F23N
1/002 20130101; F23N 2237/02 20200101; F23C 9/006 20130101; F23C
2202/40 20130101; F23R 2900/03282 20130101; F23R 2900/00013
20130101 |
Class at
Publication: |
60/776 ;
60/746 |
International
Class: |
F23R 3/34 20060101
F23R003/34 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 14, 2010 |
US |
12835960 |
Claims
1. A burner for a gas combustor, comprising: a front surface area
divided into a plurality of subareas; and inlets, arranged on the
front surface area such that each subarea is encircled by at least
four inlets and such that during operation of the burner, a gas
recirculation in the combustor is facilitated corresponding to each
subarea.
2. The burner according to claim 1, further comprises a pilot inlet
in at least one of the subareas.
3. The burner according to claim 1, wherein the inlets encircling
the subarea are spaced equally.
4. The burner according to claim 1, wherein the front surface area
comprises of two subareas.
5. The burner according to claim 1, wherein the front surface area
comprises of three subareas.
6. The burner according to claim 1, wherein the shape of said
burner is circular.
7. The burner according to claim 1, wherein the shape of said
burner is elliptical.
8. The burner according to claim 1, wherein the subareas formed by
the arrangement of the inlets on the front surface area has
symmetrical configuration.
9. The burner according to claim 1, wherein the subareas formed by
the arrangement of the inlets on the front surface area has
asymmetrical configuration.
10. The burner according to claim 1, wherein adjacent subareas on
the front surface area are adapted to use at least one inlet in
common.
11. The burner according to claim 1, wherein the inlets arranged on
the front surface area are of at least two different diameters.
12. The burner according to claim 1, wherein said burner operates
on pre-mixed jet flames.
13. A method of operating a burner with a plurality of inlets on a
front surface area of the burner to provide combustible gas to a
combustor, comprising: dividing the front surface area into a
plurality of subareas; for at least one subarea, selecting at least
four inlets which are encircling the respective subarea; and
providing combustible gas only through the selected inlets such
that a hot gas recirculation in the combustor is facilitated
corresponding to each subarea.
14. The method according to claim 13, wherein the combustible gas
is provided through at least one inlet during startup of the
combustor.
15. The method according to claim 13, wherein the number of
subareas operated during an operation of the combustor is based on
the combustor load.
16. The method according to claim 13, wherein the combustible gas
supplied through the inlets is staged based on the combustor
load.
17. The method according to claim 13, wherein the subareas formed
by the arrangement of the inlets on the front surface area has
symmetrical configuration.
18. The method according to claim 13, wherein the subareas formed
by the arrangement of the inlets on the front surface area has
asymmetrical configuration.
19. The method according to claim 13, wherein adjacent subareas on
the front surface area of the burner are adapted to use at least
one inlet in common.
Description
FIELD OF INVENTION
[0001] The present invention relates to a gas combustor burner
particularly arrangement of inlets in the burner which supplies
combustible gas to the combustor and its operation for fuel
staging.
BACKGROUND OF INVENTION
[0002] Gas turbines are used to convert heat energy to mechanical
energy, for example in power plants. Gas turbines have combustion
chambers in which a fuel is burned with air. The combustion
chambers of gas turbine plants are supplied with liquid and/or
gaseous fuel using burner consisting of one or more nozzle or
inlets. The burner can also be used to carry air required for the
combustion. For the optimal operation of the gas compressors,
stable flames should be formed in the combustion chamber during
combustion. Common techniques for flame stabilization include the
formation of small eddies or recirculation zones in the combustion
chamber. The temperature in the recirculation zone needs to be
above a threshold especially at lower load conditions to sustain
combustion which will result in stable operation.
[0003] A flame will be inherently unstable if the energy release
from the combustion is insufficient to raise the temperature to a
level at which combustion is self sustaining under conditions of
heat loss including radiation to and from the flame and under hot
gas recirculation. The ability to keep a sustainable temperature to
maintain combustion at different loads especially at lower loads
and simultaneously achieve emission targets is a great challenge in
gas turbine operations.
SUMMARY OF INVENTION
[0004] In view of the foregoing, an embodiment herein includes a
burner for a gas combustor. The burner comprises a front surface
area divided into a plurality of subareas. Inlets are arranged on
the front surface area such that each subarea is encircled by at
least four inlets such that during operation of the burner, a gas
recirculation in the combustor is facilitated corresponding to each
subarea.
[0005] In view of the foregoing, another embodiment herein includes
a method of operating a burner with a plurality of inlets on the
front surface area of the burner to provide combustible gas to a
combustor. The method comprises dividing the front surface area
into a plurality of subareas, and for at least one subarea
selecting at least four inlets which are encircling the respective
subarea. The method further comprise providing combustible gas only
through the selected inlets such that a gas recirculation in the
combustor is facilitated corresponding to each subarea.
[0006] The underlying idea here is to provide gas recirculation
inside a combustor by providing and operating inlets in at least
one subarea which is smaller than that of front surface area of the
burner. By operating the inlets encircling the subarea a gas
recirculation or gas recirculations, if more than one subarea are
operated, is formed which can maintain the sustainable temperature
for the combustion. The number of subareas operated is based on the
load of the gas turbine which can also be directly mapped to the
combustor load. Operating the inlets in a subarea or subareas also
enables staging the supply of combustible gas to the combustor for
combustion. The combustion resulting in the creating of gas
recirculation which is hot thereby resulting in maintaining the
required temperature throughout the entire load range. By operating
a single smaller subarea at lower loads, the combustion associated
with that subarea can be sustained. This combustion creates hot
recirculation which also provides stability to flames in the
combustor provided for the combustion. As the load increases other
subareas can be made operational to supply the combustible gas to
the combustor. Practically, at least four inlets are required to
realize a gas recirculation in a subarea. The staging of the
combustible gas referred in the invention should also be
interpreted as the staging of the fuel since the inlets are
generally supplied continuous by air in industrial operations.
[0007] According to a preferred embodiment, the burner further
comprises a pilot inlet in at least one of the subareas. This pilot
inlet helps in supplying flames to provide adequate temperature to
start the combustion process.
[0008] In an alternative embodiment, the inlets encircling the
subarea are spaced equally. This enables to create a stable
recirculation using the combustible gases injected into the
combustor by the inlets in the subarea.
[0009] In another alternative embodiment, the front surface area
comprises of two or three or more subareas. Having plurality of
subareas enables more flexibility or control of the supply of the
fuels to the combustor for combustion. That means the supply of the
fuels to the combustor can be staged. The more the number of
subareas, more the number of staging that can be realized. During
staging, the amount of combustible gas supplied through the inlets
in one or more subareas are regulated or controlled based on the
load of gas turbine. Also simultaneous operation of multiple
subareas will result in plurality of gas recirculation, which
further provides more tuning flexibility regarding thermo acoustic
oscillations in the gas combustor. Practically two or three gas
recirculations are optimal even though more gas recirculations can
be realized for the operation.
[0010] In another alternative embodiment, the shape of said burner
is circular or elliptical. The shape of the burner enables to
arrange the inlets in multitude of possibilities to get a gas
recirculation.
[0011] In another alternative embodiment, the subareas formed by
the arrangement of the inlets on the front surface area have
symmetrical configuration. Symmetrical configuration of the
subareas and corresponding inlets arranged will enable to provide
more stability to the combustor, if operated simultaneously.
[0012] In another alternative embodiment, the subareas formed by
the arrangement of the inlets on the front surface area has
asymmetrical configuration. This enables the burner to have
subareas having different area configurations and also possibly
with different number of inlets encircling them which further helps
in staging the combustible gas by selecting the required subarea
based on the combustor load. For example if the load is very low,
the smallest subarea can be selected for the operation.
[0013] In another alternative embodiment adjacent subareas on the
front surface area of the burner are adapted to use at least one
inlet in common. This helps in effective utilization of the front
surface area of the burner to generate effective gas
recirculation.
[0014] In another alternative embodiment, the inlets arranged on
the front surface area, to supply the combustible gas to the
combustor, are of at least two different diameters. This will help
in the operation of the required subarea which further regulates
the flow of combustible gas based on the load requirement. For
example, at lower loads the inlets with smaller diameter can be
operated and at higher loads, when more combustible gas is required
the inlets with larger diameter could be used.
[0015] In another alternative embodiment, said burner operates on
pre-mixed jet flames. Combustion systems based on pre-mixed jet
flames offer special advantages over for example, swirl stabilized
systems from the thermo-acoustic point of view, owing to the
distributed heat release zones and the absence of swirl induced
vortices. By appropriately selecting the jet impulse, small scale
eddy structures can be created which dissipate the acoustically
induced fluctuations of heat release, thereby suppressing the
pressure pulsations which are typical for swirl stabilized
flames.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] The present invention is further described hereinafter with
reference to illustrated embodiments shown in the accompanying
drawings, in which:
[0017] FIG. 1 illustrates an elliptical burner where inlets are
arranged in the front surface area of the burner so as to form two
sub areas according to an embodiment of the invention,
[0018] FIG. 2 illustrates a circular burner where inlets are
arranged in the front surface area of the burner so as to form
multiple sub areas according to an embodiment of the invention with
a central pilot inlet,
[0019] FIG. 3 illustrates a circular burner where inlets are
arranged in the front surface area of the burner so as to form
multiple sub areas according to an embodiment of the invention with
a pilot inlet in one of the subareas,
[0020] FIG. 4 illustrates a combustion chamber, showing the gas
recirculation, when operating multiple subareas in a burner as
shown in FIG. 1, and
[0021] FIG. 5 illustrates a combustion chamber, showing the gas
recirculation, when operating two subareas using a burner as shown
in FIG. 3.
DETAILED DESCRIPTION OF INVENTION
[0022] It is known that undesired thermoacoustic oscillations
frequently occur in combustors of gas turbines. The term
"thermoacoustic oscillations" designates mutually self reinforcing
thermal and acoustic disruptions. In the process, high oscillation
amplitudes can occur, which can lead to undesired effects, such as
to high mechanical loading of the combustor and increased NOx
emissions as a result of inhomogeneous combustion. In order to
ensure a high output in relation to pulsations and emissions over a
wide operating range, further tuning of the fuel distribution and
active or passive control of the combustion oscillations may be
necessary.
[0023] FIG. 1 illustrates an elliptical burner 100, where inlets
are arranged in the front surface area 101 of the burner so as to
form two subareas 102 and 104 according to an embodiment of the
invention. The inlets 105 along with the common inlets 106 encircle
the subarea 102. Likewise, inlets 107 along with the common inlets
106 encircle the subarea 104. During operation of the burner, i.e.
during combustion, a gas recirculation in the combustor is
facilitated or produced corresponding to each subarea 102 and 104
if all the inlets of the burner are operated. It is to be noted
that in this embodiment no inlet is used as a pilot inlet to start
the combustion and the inlets encircling the subarea are
substantially spaced at equal distance between them. Piloting could
even be realized by a separate burner if required or even any other
heating means can be used to provide the required temperature for
the start of the combustion.
[0024] In FIG. 1, the inlets are placed in the front surface area
to form two almost identical or symmetrical subareas. The upper
subarea 102 and the lower subarea 104 have symmetrical
configurations. The number of subareas in the FIG. 1 is limited to
two, but practically the burner could be realized by three or more
subareas. For example at low load operation of the gas turbine, the
required combustion temperature could be maintaining by supplying
the combustible gas, i.e. the fuel and air mixture through the
inlets of any one of the subarea 102 or 104. The inlets in the
other subarea will be supplied only with air, resulting in a flame
in only one of the two subareas for which the combustible gas was
supplied. The flame will generate a hot gas recirculation. The air
flowing through the other subarea also results in a recirculation,
which will not be hot, but is referred as a cold recirculation here
after for the explanation and understanding.
[0025] Also it is possible to merge the subareas during operation.
At high load operation all the inlets of the burner are used to
supply combustible gas to the combustor. The operation of all
inlets in the burner results in two hot recirculations; one formed
by the inlets of the subarea 102 and another formed by the inlets
of the subarea 104.
[0026] FIG. 2 illustrates a circular burner 200, where inlets are
arranged in the front surface area 201 of the burner so as to form
multiple sub areas 202, 204 and 206 according to an embodiment of
the invention with a central pilot inlet 209. The centralised pilot
could be used for any one or all of the subareas 202, 204 and 206.
The placement of the inlets in the front surface of the burner as
shown in FIG. 2 provides an asymmetric configuration of the
subarea, since for example the number of the inlets which encircles
each subarea varies. Also it should be noted that the size, more
specifically the diameter of few of the inlets in the subarea 206
differs from that of the inlets in subarea 202 or 204. Also between
adjacent subareas there are inlets which are common. As shown in
FIG. 2, inlet 203 is common to subarea 202 and 204. Likewise, inlet
205 is common to subarea 202 and 206 and also inlet 207 is common
to subarea 204 and 206. As previously mentioned the pilot inlet 209
is common to all the subareas. When the load on the gas turbine is
low, the inlets in the subarea 202 or 204 is operated and when the
load increases the inlets in other subareas including the subarea
206 having larger diameter could be used to supply the combustible
gas. Based on the load, different combinations of operation of the
subareas are possible enabling the staging of the combustible gas
supply to the combustor thereby resulting in complete combustion
throughout the load range and less emissions. Flame stability is
also achieved using the hot gas recirculation formed in the
combustion in the combustor. The hot recirculation formed after the
combustion gives enough temperature to sustain the combustion in
the region of recirculation resulting in a stable flame.
[0027] FIG. 3 illustrates a circular burner 300 where inlets are
arranged in the front surface area 301 of the burner so as to form
multiple subareas 302, 304 and 306 according to an embodiment of
the invention with a pilot inlet 308 in one of the subarea 306. In
the specific arrangement, the pilot inlet can initiate the
combustion first and at low loads the subarea 306 could be
operated. As the load increases other subareas can be made
operational by controlling the respective inlets to form multiple
hot recirculations.
[0028] FIG. 4 illustrates a combustion chamber, showing the gas
recirculation, when using a burner as shown in FIG. 1. FIG. 4 shows
a combustion chamber 400, of a can-type combustor. The combustion
chamber has an internal space 402 enclosed by a wall 401, which is
generally cylindrical. On the inlet side 403, a burner 404 having
plurality of inlets placed on the front surface of the burner as
shown in FIG. 1 is placed. The burner is considered to be an
elliptical burner as shown in FIG. 1. By operating all the inlets
in both the subareas the gas recirculation inside the combustion
chamber 400 will be as shown in the FIG. 4, shown by the arrows.
The gas recirculation arrows 406 shows the recirculation in the
upper region of combustion chamber 400 formed by the inlets in the
subarea 102 of FIG. 1. The gas recirculation arrows 407 shows the
recirculation in the lower region of combustion chamber 400 formed
by the inlets in the subarea 104 of FIG. 1. These recirculations
provide the flame stabilization mechanism. By staging of the
combustible gas through the inlets, the number of hot recirculation
can be controlled. The number of hot recirculation required can
also be based on the operational load conditions, the required
stability and emission requirements.
[0029] FIG. 5 illustrates a combustion chamber 500, showing the gas
recirculation when using a burner as shown in FIG. 1. The
combustion chamber has an internal space 502 enclosed by a wall
501, which is generally cylindrical. On the inlet side 503, a
burner 504 having plurality of inlets are placed. The inlets placed
in the front surface of the burner are similar to that discussed
and shown in FIG. 1. By staging the fuel only through one sub area
for example, through all the inlets in the subarea 102 of FIG. 1,
the gas recirculation inside the combustion chamber 500 will look
like what is shown in FIG. 5. The gas recirculation arrows 508 show
the hot recirculation formed by the operation of inlets in the
subarea 102 and recirculation arrows 506 shown in dotted lines
indicate the cold recirculation formed by the flow of air through
the inlets in the subarea 104. By operating the inlets in a single
or inlets in multiple subareas based on the load, the fuel staging
can be achieved and thereby the number of hot recirculation inside
the combustor can be controlled for getting flame stability.
[0030] Although the invention has been described with reference to
specific embodiments, this description is not meant to be construed
in a limiting sense. Various modifications of the disclosed
embodiments, as well as alternate embodiments of the invention,
will become apparent to persons skilled in the art upon reference
to the description of the invention. It is therefore contemplated
that such modifications can be made without departing from the
embodiments of the present invention as defined.
* * * * *