U.S. patent application number 12/814707 was filed with the patent office on 2010-12-16 for burner arrangement for a combustion system for combusting liquid fuels and method for operating such a burner arrangement.
Invention is credited to Andreas Bottcher, Tobias Krieger, Ulrich Worz.
Application Number | 20100316966 12/814707 |
Document ID | / |
Family ID | 41262140 |
Filed Date | 2010-12-16 |
United States Patent
Application |
20100316966 |
Kind Code |
A1 |
Bottcher; Andreas ; et
al. |
December 16, 2010 |
Burner arrangement for a combustion system for combusting liquid
fuels and method for operating such a burner arrangement
Abstract
A burner arrangement for a combustion system for combusting
liquid fuels including a burner hub, at least one air supply
channel and at least one fuel supply channel for each fuel type is
provided. The at least one fuel supply channel is embodied at least
partially in the burner hub, with a flow divider arranged in at
least one fuel supply channel, which is distanced from the wall of
the fuel supply channel so that an interspace associated with the
flow path of the fuel flowing through the fuel supply channel is
formed between the wall of the fuel supply channel and the flow
divider. A method for operating such a burner arrangement is also
provided.
Inventors: |
Bottcher; Andreas;
(Ratingen, DE) ; Krieger; Tobias; (Duisburg,
DE) ; Worz; Ulrich; (Orlando, FL) |
Correspondence
Address: |
SIEMENS CORPORATION;INTELLECTUAL PROPERTY DEPARTMENT
170 WOOD AVENUE SOUTH
ISELIN
NJ
08830
US
|
Family ID: |
41262140 |
Appl. No.: |
12/814707 |
Filed: |
June 14, 2010 |
Current U.S.
Class: |
431/12 ;
431/181 |
Current CPC
Class: |
F23R 3/343 20130101;
F23R 3/286 20130101 |
Class at
Publication: |
431/12 ;
431/181 |
International
Class: |
F23N 1/00 20060101
F23N001/00; F23C 7/00 20060101 F23C007/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 16, 2009 |
EP |
09162827.1 |
Claims
1.-10. (canceled)
11. A burner arrangement for a combustion system for combusting
liquid fuels, comprising: a burner hub; an air supply channel; and
a fuel supply channel for each type of fuel, wherein the fuel
supply channel is at least partially embodied in the burner hub,
wherein a flow divider is arranged in the fuel supply channel, and
wherein the flow divider is distanced from a wall of the fuel
supply channel so that an interspace associated with a flow path of
a fuel flowing through the fuel supply channel is formed between
the wall and the flow divider.
12. The burner arrangement as claimed in claim 11, wherein the flow
divider is formed by a sleeve introduced into the fuel supply
channel.
13. The burner arrangement as claimed in claim 11, wherein the flow
divider protrudes at least partially into the annular channel.
14. The burner arrangement as claimed in claim 11, wherein the flow
divider comprises a flow means including a flow-through opening,
and a disk including a corresponding flow-through opening.
15. The burner arrangement as claimed in claim 14, wherein the flow
means is a pipe.
16. The burner arrangement as claimed in claim 15, wherein a
central bore in a center of the flow divider is provided as the
flow-through opening.
17. The burner arrangement as claimed in claim 14, wherein the disk
is provided on a first end of the flow-through means, viewed in the
flow direction.
18. The burner arrangement as claimed in claim 17, wherein the disk
is clamped to the wall in a form-fit manner.
19. The burner arrangement as claimed in claim 17, wherein the disk
rests on a positioning projection.
20. The burner arrangement as claimed in claim 14, wherein the disk
includes a larger first diameter than a second diameter of the
flow-through means.
21. The burner arrangement as claimed in claim 14, wherein the flow
divider in the disk includes a bore.
22. The burner arrangement as claimed in claim 21, wherein the disk
includes a plurality of bores, which are essentially equally
distributed over the periphery.
23. A method for operating a burner arrangement, comprising:
routing fuel during operation through the fuel supply channel,
wherein a main part of a fuel flows through a flow through-opening
of the flow divider and a minimal part of the fuel flows through an
interspace of the flow divider, wherein the burner arrangement
comprises: a burner hub, an air supply channel, and a fuel supply
channel for each type of fuel, wherein the fuel supply channel is
at least partially embodied in the burner hub, wherein a flow
divider is arranged in the fuel supply channel, and wherein the
flow divider is distanced from a wall of the fuel supply channel so
that an interspace associated with a flow path of a fuel flowing
through the fuel supply channel is formed between the wall and the
flow divider.
24. The method as claimed in claim 23, wherein the flow divider is
formed by a sleeve introduced into the fuel supply channel.
25. The method as claimed in claim 23, wherein the flow divider
protrudes at least partially into the annular channel.
26. The method as claimed in claim 23, wherein the flow divider
comprises a flow means including a flow-through opening, and a disk
including a corresponding flow-through opening.
27. The method as claimed in claim 26, wherein the flow means is a
pipe.
28. The method as claimed in claim 27, wherein a central bore in a
center of the flow divider is provided as the flow-through
opening.
29. The method as claimed in claim 26, wherein the disk is provided
on a first end of the flow-through means, viewed in the flow
direction.
30. The method as claimed in claim 26, wherein the disk includes a
larger first diameter than a second diameter of the flow-through
means.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority of European Patent Office
application No. 09162827.1 EP filed Jun. 16, 2009, which is
incorporated by reference herein in its entirety.
FIELD OF INVENTION
[0002] The invention relates to a burner arrangement for a
combustion system for combusting liquid fuels and method for
operating such a burner arrangement with the features cited in the
preambles of the respective independent claims.
BACKGROUND OF INVENTION
[0003] With respect to universal efforts to reduce the pollutant
emissions of combustion systems, particularly in gas turbines,
burners were developed over the last few years which have
particularly minimal nitrogen oxide (NOx) emissions. Considerable
importance is attached here to such burners not only being operable
with one fuel, but instead as far as possible with various fuels,
for instance oil, domestic gas and/or coal gas or in combination,
in order to increase the supply reliability and flexibility of the
operation. Such burners are described for instance in EP 0 276 696
B1.
[0004] One problem with the design of burners for all possible
different operating conditions and operating materials consists in
the volume of the individual operating materials needed during
operation being different in each instance so that it becomes
difficult for all operating materials to use the same supply system
and the same injection openings. It is therefore known in the prior
art to use different supply systems for liquid and gaseous
mediums.
[0005] A further problem nevertheless also arises if gaseous fuels
are then optionally also to be used with completely different
specific fuel values, for instance natural gas and coal gas. The
different relative volume ratios when using these two fuels and the
different chemical processes during their combustion require a
modification or extension of the known systems.
[0006] It is known for inert substances, in particular water or
water vapor, to be injected in order to reduce the pollutant
emissions in certain operating states, as a result of which the
combustion temperature is reduced and the Nox pollutant emissions
are consequently lowered. WO 89/08803 A1 also discloses that with
the use of heavy oils as fuel, for example, admixtures should also
be mixed with the injected substances in order to prevent damage to
components of a subsequent gas turbine.
[0007] EP 0 276 696 B1 discloses a hybrid burner for premixing
operation with gas and/or oil, like is used in particular for gas
turbine systems. The burner consists of a central pilot burner
system, which can be operated with gas and/or oil as a so-called
diffusion burner or a separate premix burner. Provision is also
made for the possibility of feeding inert substances. The pilot
burner system is surrounded by a main burner system, which has an
air supply annular channel system with a helical blading located
therein having a plurality of blades for the premixing operation
with gas. Inlet nozzles for oil are also present in the region of
the helical blading in the main burner system, thereby enabling the
main air flow to be premixed with oil.
[0008] DE 42 12 810 B4 and EP 0 580 683 B1 emanating therefrom
describe the prior art closest to the present invention. It is
assumed here that when combusting combustion gas with a low fuel
value, no special measures are needed to reduce the pollutant
emission, since when combusting such gases, no excessively high
flame temperatures occur and the formation of Nox therefore remains
practically insignificant. It is therefore sufficient to create a
further simple supply system, with attention having to be paid to
ensuring that this system does not disadvantageously influence the
other systems and does not reduce the operational reliability
during operation of the other systems. It is therefore important
for the further annular channel to open for the other fuels on the
inflow side above the outlet nozzles. In this way, no ignitable
mixture can reach the further annular channel if the burner is
supplied with a different type of fuel through the outlet
nozzles.
[0009] One challenge with these burners emerges as a result of the
mechanical stresses in the walls of the metallic housing, the
so-called hub, which occur due to an uneven thermal distribution,
in which hub the supply annular channels of the gas and oil energy
carriers, are arranged relatively close to one another. An annular
gas compartment supplies the main burner in respect of the flow
direction of the inflowing air on the input side upstream of the
so-called helical blades, which convey a mixed helix to the air
flow with the combustion gas or through the helical blades. An oil
supply is also available as the gas supply, which is generally
arranged in the vicinity of the burner outlet. It includes an
annular oil compartment, and an oil supply channel leading to the
annular compartment, which is arranged in the hub wall located
between the annular gas compartment and the pilot burner.
[0010] As gas has a lower density than oil, it requires a larger
cross-section, as a result of which the dimensioning of the gas
supply is considerably larger than the oil supply. The part of the
burner hub with the gas supply therefore has a larger external
surface facing the air channel than the oil supply. The air supply
takes place with precompressed air, which has passed through a
compressor, as a result of which this supplied air has a
temperature, as a result of the compression, which already reaches
above 400.degree. C. The region of the burner hub with the gas
supply is consequently rapidly heated to a temperature in the
region of above 400.degree. C. and remains at this operating
temperature. The oil supply channel leading to the annular oil
compartment is by contrast distanced far from the hot air supply
channel so that the oil in the oil supply channel barely
experiences any heating and thus only has a temperature of
approximately 50.degree. C.
[0011] As, on the one hand, the burner hub experiences a strong
heating in the region of the annular gas compartment and, on the
other hand, the adjacent oil supply channel is considerably cooler,
the wall between the annular gas compartment and the oil supply
channel is subjected to a large temperature gradient both during
continual operation and also when flushing out the burner hub. If
the hub, i.e. the oil channel, is flushed with water, the gas
channels remain hot and the oil channel cools down significantly.
The channels are very close to one another as a result of the
limited space in the hub and high temperature/thermal gradients
result. As a result of the temperature gradient, thermal stresses
result, which significantly shorten the service life of such burner
hubs.
SUMMARY OF INVENTION
[0012] The object of the present invention is thus to reduce the
described thermally specific stresses in the burner hub during
operation and when flushing the hub of the burner arrangement.
[0013] This object is achieved by a burner arrangement as claimed
in the claims and/or a method for operating such a burner
arrangement as claimed in the claims. The dependent claims contain
advantageous embodiments of the invention.
[0014] An inventive burner arrangement for a combustion system for
combusting liquid fuels includes a burner hub, at least one air
supply channel and at least one fuel supply channel for each type
of fuel. The at least one fuel supply channel is embodied at least
partially in the burner hub, so that the material of the burner hub
forms a wall of the fuel supply channel. In accordance with the
invention, a flow divider is provided in at least one fuel supply
channel, said flow divider being distanced from the wall of the
fuel supply channel so that an interspace associated with the flow
path of the fuel flowing through the fuel supply channel is formed
between the wall of the fuel supply channel and the flow
divider.
[0015] In the inventive burner arrangement, the interspace forms a
region associated with the flow path, in which an adjustable
continual fuel flow flows. This fuel flow prevents deposits from
forming in the interspace and thus prevents a blockage of the
nozzles through which the fuel escapes. Furthermore, the flow in
this region decouples the hot structure from the cold structure and
thus represents a heat shield. As a result of the reduced thermal
transfer, the thermally specific stresses reduce compared with the
burner arrangements without a flow divider.
[0016] In the inventive burner arrangement, the flow divider
consists of a flow-through means, in particular a pipe with a
flow-through opening, and a disk with a corresponding flow-through
opening. A central bore in the center of the flow divider is
preferably provided as a flow-through opening. The majority of the
fuel flows through this central bore.
[0017] When viewed in the flow direction, the disk is also provided
at the first end on the flow-through means.
[0018] In a preferred embodiment, the disk has a larger diameter
than the diameter of the flow-through means. The disk can be
clamped here in the wall of the fuel supply channel. Positioning
means, e.g. a positioning projection, can however also be provided
on the wall of the fuel supply channel.
[0019] The flow divider in the disk preferably has at least one
bore. The disk also has several bores, which are essentially
distributed equally over the periphery. These bores route a small
part of the preferably cold fuel flow into the interspace, with the
hot carrier structure thus being thermally decoupled from the
inflowing cold fuel. The heat transfer in this region is thus
reduced.
[0020] According to a further aspect of the present invention, said
object is achieved by a method for operating such a burner
arrangement, with, during operation, fuel being routed through the
fuel supply channel, with the majority of the fuel flowing through
the flow-through opening of the flow divider and a small part of
the fuel flowing through the interspace of the flow divider,
thereby largely preventing deposits in the interspace.
[0021] A small part of the flow is thus routed through the
interspace and thus prevents the formation of deposits in the
interspace, in other words, above all on the wall of the carrier
structure of the combustion chamber hub. A blockage of the nozzles
is thus prevented.
[0022] Through the minimal flow, a function as a heat protection
shield is provided, since the hot carrier structure is thermally
decoupled from the inflowing cold fuel, in particular from cold
oil. The main flow for supplying the nozzles flows through the
flow-through opening of the flow divider, with this flow-through
opening preferably being provided as a large, central bore in the
center of the flow divider. High temperatures and stress gradients
therefore no longer form. A significant increase in the service
life is the desired result.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] Further features, properties and advantages of the invention
result from the following description of an exemplary embodiment
with reference to the appending figures, in which;
[0024] FIG. 1 shows a burner arrangement known from EP 0 580 683
B1,
[0025] FIG. 2 shows a partial cross-sectional view through a known
burner arrangement,
[0026] FIG. 3 shows a basic diagram of an inventive helical blade
with two integrated gas stages which can be controlled
independently of one another,
[0027] FIG. 4 shows a basic diagram of a burner chamber hub with
two integrated gas stages, which can be controlled independently of
one another and an oil channel,
[0028] FIG. 5 shows a burner chamber hub 18 with an inventive flow
divider 40,
[0029] FIG. 6 shows an inventive flow divider 40.
DETAILED DESCRIPTION OF INVENTION
[0030] FIG. 1 shows a burner arrangement 20 as claimed in the prior
art, which, if necessary in conjunction with several similar
arrangements, can be used in the combustion chamber of a gas
turbine system for instance.
[0031] It consists of an inner part, the pilot burner system and an
outer part, the main burner system, which is disposed
concentrically thereto. Both systems are suited to operation with
gaseous and/or liquid fuels in any combination. The pilot burner
system consists of a central oil supply 1 (medium G) and an inner
gas supply channel 2 (medium F) arranged concentrically around the
latter. This is in turn surrounded by an inner air supply channel 3
(medium E) which is arranged concentrically around the axis of the
burner.
[0032] A suitable ignition system can be arranged in or on this
channel, for which many embodiment possibilities are known and the
representation thereof was therefore omitted here. The central oil
supply 1 has an oil nozzle 5 at its end and the inner air supply
channel 3 has a helical blading 6 in its end region. A pilot burner
system 1, 2, 3, 5, 6 can be operated in a manner known per se, i.e.
predominantly as a diffusion burner. Its task is to keep the main
burner stable during combustion, since this is mostly operated with
a lean mixture which tends towards instabilities.
[0033] The main burner system has an outer air supply annular
channel system 4 which is arranged concentrically with respect to
the pilot burner system and runs obliquely thereto. This air supply
annular channel system 4 is also provided with a helical blading 7.
The helical blading 7 consists of hollow blades with outlet nozzles
11 in the flow cross-section of the air supply annular channel
system 4 (medium A). These are fed from a supply line 8 and an
annular channel 9 through openings 10 for the medium B. The burner
also has a supply line 12 for a medium C, preferably oil, which
opens into an annular channel 13, which has outlet nozzles 14 for
the medium C in the region or below the helical blading 7.
[0034] A spray jet 15 of the medium C is also shown. In accordance
with the invention, the burner also has a further coal gas supply
channel 16 for medium D. This opens into the outer air supply
annular channel system 4, just above the helical blading 7 with the
outlet nozzles 11, and on its internal side, so that in principle
both together form a diffusion burner.
[0035] FIG. 2 shows an enlarged partial cross-sectional view
through a known burner hub 18 as claimed in the prior art. The
burner arrangement is circular, so that the annular channel 9 and
13 can also be represented as circular.
[0036] The region of the main burner in FIG. 1 can also be realized
similarly. The helical blades 9 only have a supply channel with the
outlet nozzles 11, which are preferably provided to inject a
gaseous medium B. An outlet nozzle 14 for injecting preferably
liquid medium V is provided therebelow in the flow direction. A
plurality of outlet nozzles 14 is arranged along the circular
annular channel 13, so that the injection of the medium C can take
place equally in the similarly circular combustion chamber.
[0037] Contrary to FIG. 1, this representation nevertheless only
has one gas supply line and one oil supply line.
[0038] FIG. 3 shows a basic diagram of a helical blade 7 with two
integrated gas stages B and D which can be controlled independently
of one another.
[0039] The helical blade 7 has two supply channels 11 and 21 which
are independent of one another. The one supply channel with the
outlet nozzles 11 can be used to inject the medium D for instance
and the second supply channel 21 can be used to inject the medium B
by way of the outlet nozzles 24. Both mediums to be injected
through the supply channels of the helical blade 7 are preferably
gaseous, e.g. the one natural gas and the other coal gas. An inert
substance such as water vapor for instance can similarly be
injected by way of these outlet nozzles 11 and/or 21 as
required.
[0040] FIG. 4 shows a fuel hub 18 with the supply channel 16, the
annular channels 9 and 13 and openings 10, which lead the fuel into
the blade 7.
[0041] If the supply channel 12, subsequently referred to as oil
channel 12, is flushed with water, different temperature
distributions result. The two gas supplies remain hot and the oil
channel 12 cools down significantly. The adjusting high thermal
gradients between the flushed oil channel and the heated gas
passages reduce the service life of the fuel hub 18.
[0042] FIG. 5 shows an inventive fuel hub 18 with a flow divider
40. The flow divider 40 (FIG. 6) consists of a pipe 45 with a
flow-through opening 55 (subsequently referred to as pipe opening
55). A disk 42 is attached to the first end of the pipe 45 when
viewed in the flow direction. The disk 42 likewise has a pipe
opening 55, which corresponds to the pipe opening 55. The diameter
of the disk 42 is larger than the diameter of the pipe 45. As a
result, an interspace 38 font's in the flow direction between the
wall 21 and the pipe 45, so that the flow divider almost adopts the
form of a double pipe, namely the pipe 45 and the wall 21, which is
likewise embodied here in the manner of a pipe. The disk 42 can
essentially be attached e.g. clamped to the wall 21 in a faun-fit
manner. The embodiment of a positioning projection 35 is also
possible, on which the disk 42 rests. Bores 50 are attached in the
disk 42. These bores 50 are preferably evenly distributed over the
periphery. As a result of the bores in the flow divider 40 attached
above the disk 42, a fluid flow is divided. An adjustable small
part of the flow is routed through these smaller bores 50 into the
interspace 38. This fluid flow thus prevents the formation of
deposits in the interspace 38 and a blockage of the nozzles 14. The
minimal flow also functions as a heat protection pipe. In addition,
the reduced flow in this region decouples the hot structure from
the code and thus represents a heat shield. The hot carrier
structure is thus thermally decoupled from the inflowing fuel,
preferably cold oil. The main flow for supplying the nozzles 14
also flows through the pipe opening 55. This is preferably realized
as a central bore in the center of the flow divider 40. As a result
of the flow divider 42 and a minimal flow of the fuel in the
interspace 38, the thermal transfer a in the interspace is
essentially less than the thermal transfer .alpha..sub.previous
without the flow divider at the same point; therefore
.alpha.<<.alpha..sub.previous. The main flow for supplying
the nozzle 14 nevertheless also flows through the central bore, in
other words through the pipe opening 55. The thermal transfer
.alpha. essentially remains unchanged here, i.e.
.alpha..apprxeq..alpha..sub.previous.
[0043] As result of the minimal flow in the interspace 38, the flow
divider 40 therefore functions as a heat protection shield and the
hot carrier structure is thus decoupled from the inflowing cold
oil. High temperature and tensile gradients therefore no longer
form. The service life of the combustion chamber hub 19 is thus
significantly increased.
[0044] The inventive flow divider 40 thus divides the fluid flow
namely into a minimal flow, which flows through the interspace 38
and a quantitative main flow, which flows through the pipe opening
55. The flow divider 40 thus prevents deposits and a blockage of
nozzles when using liquid fuels. The reduced flow also decouples
the hot structure from the cold and thus represents a heat shield.
Furthermore, high thermal gradients and thermal stresses resulting
therefrom are prevented by way of a minimal cross-section. With the
use of the flow divider 40, the component 18 can thus fulfill the
high demands in terms of service life. The flow divider 40 is
simple to manufacture and easy to adapt in existing fuel chamber
hubs 18.
* * * * *