U.S. patent application number 15/747502 was filed with the patent office on 2018-08-02 for a premixed dual fuel burner with a tapering injection component for main liquid fuel.
This patent application is currently assigned to Siemens Aktiengesellschaft. The applicant listed for this patent is Siemens Aktiengesellschaft. Invention is credited to Nicklas Johansson, Thomas Lindgren, Magnus Persson.
Application Number | 20180216828 15/747502 |
Document ID | / |
Family ID | 53938197 |
Filed Date | 2018-08-02 |
United States Patent
Application |
20180216828 |
Kind Code |
A1 |
Johansson; Nicklas ; et
al. |
August 2, 2018 |
A PREMIXED DUAL FUEL BURNER WITH A TAPERING INJECTION COMPONENT FOR
MAIN LIQUID FUEL
Abstract
A premixed dual fuel burner includes a burner head, a burner
interior elongated along a main axis and having an upstream side
enclosed by a swirler and a downstream side enclosed by a premixing
section, and an injection component. The burner head and sides are
serially arranged. The swirler includes an inlet section for
introducing air and a main gas fuel. The injection component has a
tapering structure positioned along the main axis which extends
from the burner head into the burner interior. The injection
component tapers from a burner head side and an injection side
along the main axis. At the injection side a liquid fuel outlet
introduces a main liquid fuel into the burner interior. The
injection side is disposed in the burner interior. At least one of
the at least one liquid fuel outlet is at a side of the injection
side of the injection component.
Inventors: |
Johansson; Nicklas;
(Skarblacka, SE) ; Lindgren; Thomas; (Norrkoping,
SE) ; Persson; Magnus; (Svartinge, SE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Siemens Aktiengesellschaft |
Munich |
|
DE |
|
|
Assignee: |
Siemens Aktiengesellschaft
Munich
DE
|
Family ID: |
53938197 |
Appl. No.: |
15/747502 |
Filed: |
July 29, 2016 |
PCT Filed: |
July 29, 2016 |
PCT NO: |
PCT/EP2016/068139 |
371 Date: |
January 25, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F23C 2900/07001
20130101; F23R 3/286 20130101; F23C 1/08 20130101; F23R 3/14
20130101; F23C 2900/07002 20130101; F23C 2900/07021 20130101; F23D
11/40 20130101; F23R 3/36 20130101; F23D 11/402 20130101 |
International
Class: |
F23R 3/28 20060101
F23R003/28; F23R 3/14 20060101 F23R003/14; F23R 3/36 20060101
F23R003/36; F23D 11/40 20060101 F23D011/40 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 20, 2015 |
EP |
15181707.9 |
Claims
1. A premixed dual fuel burner for a combustion chamber of a
turbomachine, the premixed dual fuel burner comprising: a burner
head having a burner head end, a burner interior elongated along a
main axis and having an upstream side and a downstream side,
wherein the upstream side is disposed between the burner head and
the downstream side and wherein the upstream side is fluidly
connected to the downstream side, a swirler enclosing the upstream
side of the burner interior and comprising an inlet section
configured to introduce air and a main gas fuel into the burner
interior, a premixing section enclosing the downstream side of the
burner interior, wherein the swirler is arranged between the burner
head and the premixing section, and wherein the premixing section
comprises a burner outlet configured to be arranged with the
combustion chamber such that the downstream side is fluidly
connected to the combustion chamber, and an injection component
having a tapering structure positioned along the main axis and
extending from the burner head into the burner interior, the
injection component having a burner head side and an injection side
and wherein the injection component tapers from the burner head
side to the injection side along the main axis, wherein the
injection component comprises at least one liquid fuel outlet at
the injection side and the injection component is configured to
introduce a main liquid fuel into the burner interior through the
at least one liquid fuel outlet and wherein the injection side of
the injection component is disposed in the burner interior, and
wherein at least one of the at least one liquid fuel outlet is at a
side of the injection side of the injection component.
2. The premixed dual fuel burner according to claim 1, wherein the
tapering structure of the injection component is a conical
structure.
3. The premixed dual fuel burner according to claim 1, wherein the
tapering structure of the injection component is arranged coaxially
to the main axis.
4. The premixed dual fuel burner according to claim 1, wherein a
first distance along the main axis between the at least one liquid
fuel outlet and the burner head end is between 20% and 80% of a
second distance along the main axis between the burner outlet of
the premixing section and the burner head end.
5. The premixed dual fuel burner according to claim 1, wherein the
injection component is configured to be longitudinally adjustable
such that a position of the at least one liquid fuel outlet of the
injection component is changeable from a first location along the
main axis to a second location along the main axis.
6. The premixed dual fuel burner according to claim 1, wherein the
at least one liquid fuel outlet is positioned in the upstream side
of the burner interior.
7. The premixed dual fuel burner according to claim 1, wherein the
at least one liquid fuel outlet is positioned in the downstream
side of the burner interior.
8. The premixed dual fuel burner according to claim 1, wherein the
injection component comprises a second additional outlet configured
to introduce the main liquid fuel into the burner interior and
wherein the second additional outlet is at an end of the injection
side, particularly at a tip, of the injection component.
9. The premixed dual fuel burner according to claim 1, wherein the
inlet section of the swirler comprises at least one air inlet and
at least one main fuel gas inlet.
10. The premixed dual fuel burner according to claim 9, wherein at
least one of the at least one air inlet and the at least one main
fuel gas inlet is arranged tangentially along the swirler with
respect to the main axis.
11. The premixed dual fuel burner according to claim 1, wherein the
swirler has a conical frustum shape having a top side and a bottom
side and wherein a cross-section of the conical frustum increases
from the top side towards the bottom side and wherein the top side
is connected to the burner head and the bottom side is connected to
the pre-mixing section.
12. The premixed dual fuel burner according to claim 1, wherein a
part of the premixing section surrounding the burner outlet of the
premixing section comprises an external pilot configured to
introduce a pilot fuel into the combustion chamber.
13. The premixed dual fuel burner according to claim 1, wherein a
radial width of the injection component reduces over an axial
distance D by only or less than D/10.
14. The premixed dual fuel burner according to claim 1, wherein a
radial width of the injection component reduces over an axial
distance D by only or less than D/15.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is the US National Stage of International
Application No. PCT/EP2016/068139 filed Jul. 29, 2016, and claims
the benefit thereof. The International Application claims the
benefit of European Application No. EP15181707 filed Aug. 20, 2015.
All of the applications are incorporated by reference herein in
their entirety.
FIELD OF INVENTION
[0002] The present invention relates to turbomachine components and
more particularly to a burner for a dual fuel based combustion
chamber for a turbomachine.
BACKGROUND OF INVENTION
[0003] In modern day turbomachines, dual fuel i.e. a liquid fuel
and a gaseous fuel, are used advantageously as main fuels in many
applications for example in Lean Premix combustions, Dry Low
NO.sub.X combustions, and so and so forth. In present day
turbomachines that employ dual fuel combustion techniques, a burner
assembly in a combustion section includes a burner head connected
to a swirl generator or swirler that in turn is connected to a
mixer or premixing pathway or section. The burner assembly is
connected to or assembled with a combustion chamber. In combustion
section of the turbomachines that use the dual fuel techniques, the
main fuels, distinct from pilot fuel supplies, are mostly both
gaseous and liquid.
[0004] The basic technique in such dual fuel combustions is to
premix the main fuel with air from a compressor of the turbomachine
before igniting the combustion mixture, i.e. mixture of the air
from the compressor and the main fuel, in the combustion chamber.
Usually the air from the compressor is mixed with the main gaseous
fuel, either inside the swirler or just before introduction into
the swirler, and then swirled by the swirler to create a swirling
flow of the air and the main gaseous fuel. This swirling flow of
the pressurized air from the compressor and the main gaseous fuel
then enters from the swirler into the premixing section. At the
premixing section the pressurized air from the compressor and the
main gaseous fuel are allowed to mix well before exiting into the
combustion chamber or the combustion space where the combustion
mixture undergoes combustion.
[0005] In dual fuel combustors, or combustion sections, the main
liquid fuel is discharged by a nozzle positioned at the burner
head. The main liquid fuel after exiting the nozzle, advantageously
in atomized form, enters the swirler and then continues into the
premixing section and finally into the combustion chamber where the
main liquid fuel participates in the combustion reaction.
[0006] Also known are burners with a central fuel lance to provide
for gaseous and/or liquid fuel. One configuration of a cylindrical
central fuel lance is known from the patent publication US
2010/0273117 A1.
[0007] Further, U.S. Pat. No. 5,791,894 A shows a conical inner
body within a premix burner, to generate a swirl about an axis by
swirling of a medium around the inner body. The inner body may
comprise optionally also a bore to provide liquid fuel and/or air
to a front region of the combustion space.
[0008] However, there are some disadvantages in the scheme of
presently known dual fuel burners and as described above. Firstly,
discharging of the main liquid fuel at the burner head interferes
with the swirl generation performed by the swirler by increasing
the aerodynamic disturbances inside the swirler. Furthermore, the
aerodynamic disturbances also adversely affect an axial flow of the
combustion mixture and/or its components, i.e. flow of the
combustion mixture and/or its constituents from a burner head side
of the burner towards the combustion chamber. Secondly, since the
main liquid fuel is discharged before the swirler or just at the
beginning of the swirler, in some cases parts of the main liquid
fuel get deposited on surfaces of inside walls of the swirler
and/or the premixing section. This deposition of the main liquid
fuel residues leads to clogging of the interiors of the swirler and
especially the interiors of the premixing section. The clogging
results in loss of efficiency and in most cases the turbomachine
operation is required to be stopped to clean the main liquid fuel
residues deposited on surfaces of inside walls of the swirler
and/or the premixing section.
[0009] Furthermore, as a result of the clogging and the aerodynamic
disturbances, as mentioned above, a flow of combustion mixture
and/or components of the combustion mixture is jeopardized which
leads into increased possibility of formation of recirculation
zones within burner interiors such as the premixing section. The
formation of the recirculation zones within the burner interiors is
undesirable, as it may result into overheating of the burner
components for example the premixing section and/or the swirler. A
continued problem of overheating over an extended period of time
may result into damaging of the parts of the burner components i.e.
the premixing section, the swirler, etc. Moreover, as a result of
the formation of the undesired recirculation zones within the
premixing section, efficiency of the turbomachines in operation is
reduced.
SUMMARY OF INVENTION
[0010] An object of the present technique is to obviate the above
mentioned disadvantages and to ensure that recirculation zones for
the combustion are formed at a desired spatial position in the
combustion chamber or the combustion space. It is undesirable to
allow formation of the recirculation zone within the premixing
section of the burner. Achieving this object increases the
combustion efficiency and thus the efficiency of the overall
turbomachine, elongates operational life of the components of the
burner and associated structures that may otherwise get over heated
due to formation or extension of recirculation zones at undesirable
spatial positions within the burner interiors, and stabilizes the
combustion reaction due to control on the recirculation zone
formation and its spatial position in the combustion chamber.
[0011] The above objects are achieved by a premixed dual fuel
burner of the present technique. Advantageous embodiments of the
present technique are provided in dependent claims. Features of the
independent claim may be combined with features of dependent
claims, and features of dependent claims can be combined
together.
[0012] According to the present technique, a premixed dual fuel
burner for a combustion chamber of a turbomachine is presented. The
premixed dual fuel burner, hereinafter referred to as the burner,
includes a burner head, a burner interior, a swirler, a premixing
section and an injection component. The swirler is arranged in
series between the burner head and the premixing section. The
burner head includes a burner head end. The burner interior is
elongated along a main axis of the burner and is formed of an
upstream side and a downstream side. The upstream side is disposed
between the burner head and the downstream side. The upstream side
is fluidly connected to the downstream side, i.e. the upstream side
and the downstream side are continuous and together form the burner
interior. A part of the burner interior enclosed by the swirler is
the upstream side of the burner interior and the other part of the
burner interior enclosed by the premixing section is the downstream
side of the burner interior. The swirler includes an inlet section.
The inlet section is configured to introduce air and a main gas
fuel into the burner interior. The premixing section has a burner
outlet through which the premixing side is configured to be
arranged or fixed or assembled with the combustion chamber such
that the downstream side is fluidly connected to the combustion
chamber.
[0013] The injection component has a tapering structure positioned
along the main axis. The tapering structure of the injection
component extends from the burner head into the burner interior.
The injection component has a burner head side and an injection
side. The injection component tapers from the burner head side to
the injection side along the main axis. The injection component
includes at least one liquid fuel outlet at the injection side. The
injection component is configured to introduce a main liquid fuel
into the burner interior through the at least one liquid fuel
outlet. The main liquid fuel introduced in the burner interior by
the injection component via the liquid fuel outlet is directed
towards the combustion chamber. The injection side of the injection
component is disposed in the burner interior.
[0014] Besides, at least one of the at least one liquid fuel outlet
is at a side i.e. a side face of the tapering--of the injection
side of the injection component. Thus, the liquid fuel outlet is
angled in respect of an axial direction of the burner.
[0015] The injection component is particularly a fuel lance.
[0016] The tapering structure of the injection component minimizes
aerodynamic disturbances in the burner interior, and thus ensuring
efficient functioning of the swirler in generating swirl which in
turn aids in achieving a desired spatial position of a central
recirculation zone, advantageously the central recirculation zone
or the main recirculation zone is formed and limited completely
within the combustion chamber, and thus minimizing possibilities of
a flashback into the burner interior. Furthermore, the tapering
structure of the injection component facilitates an axial velocity,
i.e. along the main axis, of the combustion mixture i.e. the main
fuel gas and the air mixture exiting from the swirler into the
premixing section and continuing further into the combustion
chamber. The facilitation of the axial velocity results from
directed flow of the combustion mixture and/or its constituents
along the tapering structure. The tapering form of the injection
component acts as a guide to the flow of main gas fuel and air
facilitating the axial flow direction. This also helps in achieving
the desired spatial position of the recirculation zone, which is
advantageously positioned in the combustion chamber and outside the
premixing section. The positioning of the recirculation zone
outside the premixing zone and within the combustion chamber
minimizes possibilities of a flashback into the burner interior for
example into the premixing section interior.
[0017] Furthermore, by introducing the main liquid fuel via the
liquid fuel outlet on the injection component extending into the
burner interior and by directing the main liquid fuel towards the
combustion chamber, it is ensured that deposition of residues of
the main liquid fuel is minimized in inner walls of the swirler
and/or the premixing section, and thus clogging of the burner
cavity enclosed by the swirler and/or the premixing section is at
least partially prevented which in turn leads to proper swirl
action by the swirler and/or proper fuel premixing action by the
premixing section and which subsequently also helps in formation of
the recirculation zone at the desired spatial position and in
increasing efficiency of the turbomachine.
[0018] In an embodiment of the burner, the tapering structure of
the injection component is a conical structure. The conical
structure has advantageously a regular geometrical shape i.e. the
conical structure is symmetrical about a longitudinal axis of the
conical structure. The tapering of the structure is smooth and
gradual. The regular conical structure helps in further reduction
of the aerodynamic disturbances in the burner interior. Moreover,
the conical shape being a regular shape is easy to manufacture and
assemble.
[0019] In another embodiment of the burner, the tapering structure
of the injection component is arranged coaxially to the main axis.
The longitudinal axis of the conical structure overlaps with the
main axis. This adds symmetry to the burner interior and this
facilitates the further reduction of the aerodynamic disturbances
in the burner interior.
[0020] In another embodiment of the burner, a first distance is
between 20% and 80% of a second distance. The first distance is a
distance measured along the main axis between the at least one
liquid fuel outlet and the burner head end. The second distance is
a distance measured along the main axis between the burner outlet
of the premixing section and the burner head end, in other words a
length of the burner interior along the main axis. Thus, the main
liquid fuel is transported, confined within the injection
component, at least partially through parts of the burner interior
that are enclosed by the swirler and/or the premixing section and
is delivered into the burner interior at a desired position within
the burner interior depending on a ratio of the first and the
second distances. By maintaining a proper ratio of the first and
the second distances, the main liquid fuel is ejected or injected
out into the burner interior at a desirable position in the burner
interior thus at least partially decreasing the risk of spraying
the liquid fuel on surfaces of the inner walls of the swirler
and/or the premixing section.
[0021] In another embodiment of the burner, the injection component
is configured to be longitudinally adjustable along the main axis
such that a position of the at least one liquid fuel outlet of the
injection component is changeable from a first location along the
main axis to a second location along the main axis. Thus a
desirable position in the burner interior to eject or inject out
the main liquid fuel can be adjusted during an operation of the
turbomachine and/or may be set as desired between two operations of
the turbomachine.
[0022] In another embodiment of the burner, the at least one liquid
fuel outlet is positioned in the upstream side of the burner
interior. This provides an embodiment in which, if so desired for a
particular mode of operation of the turbomachine, the main liquid
fuel can be injected out of the liquid fuel outlet before the
premixing section.
[0023] In another embodiment of the burner, the at least one liquid
fuel outlet is positioned in the downstream side of the burner
interior. This provides an embodiment in which, if so desired for a
particular mode of operation of the turbomachine, the main liquid
fuel can be injected out of the liquid fuel outlet into the burner
interior enclosed by the premixing section. Furthermore, this
embodiment ensures that spraying of the liquid fuel on surfaces of
the inner wall of the swirler and at least a part of the surfaces
of the inner wall of the premixing section are minimized.
[0024] In another embodiment of the burner, one of the at least one
liquid fuel outlet is at an end of the injection side of the
injection component, particularly at a tip of the injection
component. The end is the most axial position of the injection
component. This ensures that a spray or a fluid stream of the main
liquid fuel is directed along the main axis towards the combustion
chamber. According to the invention a further one also called
"first additional outlet"--of the at least one liquid fuel outlet
is at a side of the injection side of the injection component. The
first additional outlet is configured to introduce the main liquid
fuel into the burner interior. The first additional outlet is at a
side of the injection side of the injection component. This
provides an additional direction in which an additional spray or an
additional fluid stream of the main liquid fuel is directed towards
the combustion chamber. This additional direction is at an acute
angle to the main axis and is directed towards the combustion
chamber.
[0025] According to the invention, the at least one liquid fuel
outlet is at a side of the injection side of the injection
component. This ensures that a spray or a fluid stream of the main
liquid fuel is directed towards the combustion chamber along an
angle to the main axis. This direction is at an acute angle to the
main axis and is directed towards the combustion chamber. In a
related embodiment, the injection component includes a second
additional outlet configured to introduce the main liquid fuel into
the burner interior. The second additional outlet is at an end of
the injection side of the injection component. This provides an
additional direction, i.e. along the main axis, in which an
additional spray or an additional fluid stream of the main liquid
fuel is directed towards the combustion chamber.
[0026] In another embodiment of the burner, the inlet section of
the swirler includes at least one air inlet and at least one main
fuel gas inlet. Thus the main gas fuel and the air from a
compressor of the turbomachine may be introduced into the burner
interior separately at the swirler. In an alternate embodiment, the
main gas fuel and the air from the compressor may be introduced via
a common inlet.
[0027] In another embodiment of the burner, the at least one air
inlet and/or the at least one main fuel gas inlet is arranged
tangentially along the swirler with respect to the main axis. This
provides a commonly used embodiment of the swirler and thus the
burner of the present technique may be realized, operated and
manufactured with ease.
[0028] In another embodiment of the burner, the swirler has a
conical frustum shape having a top side and a bottom side. A
cross-section of the conical frustum increases from the top side
towards the bottom side. The top side is connected to the burner
head and the bottom side is connected to the pre-mixing section.
This provides another commonly used embodiment of the swirler and
thus the burner of the present technique may be realized, operated
and manufactured with ease.
[0029] In an embodiment, the premixed dual fuel burner may have a
radial width taken in a radial direction in respect of an axis of
the burner--of the injection component that reduces over an axial
distance D by only or less than D/10, advantageously less than
D/15. In other embodiment the radial width may reduce by less than
D/20.
[0030] In another embodiment of the burner, the premixing section
has a part of the premixing section which surrounds the burner
outlet of the premixing section. The part of the premixing section
includes an external pilot. The external pilot is configured to
introduce a pilot fuel into the combustion chamber. This aids in
formation an external recirculation zone in the combustion chamber
and thus aiding in lean combustion. Furthermore the present
technique may be implemented in turbomachines that use Dry Low
NO.sub.x combustions.
BRIEF DESCRIPTION OF THE DRAWINGS
[0031] The present technique is further described hereinafter with
reference to illustrated embodiments shown in the accompanying
drawing, in which:
[0032] FIG. 1 schematically illustrates a cross-sectional view of
an exemplary embodiment of a premixed dual fuel burner including an
injection component,
[0033] FIG. 2 schematically illustrates a cross-sectional view of
the injection component of the embodiment depicted in FIG. 1,
[0034] FIG. 3 schematically illustrates a cross-sectional view of
another exemplary embodiment of the premixed dual fuel burner
including the injection component,
[0035] FIG. 4 schematically illustrates a cross-sectional view of
the injection component of the embodiment depicted in FIG. 3,
[0036] FIG. 5 schematically illustrates a cross-sectional view of
an exemplary embodiment of the premixed dual fuel burner depicting
the injection component at a first position,
[0037] FIG. 6 schematically illustrates a cross-sectional view of
an exemplary embodiment of the premixed dual fuel burner depicting
the injection component at a second position as compared to the
first position depicted in FIG. 5, and
[0038] FIG. 7 schematically illustrates a cross-sectional view of
an exemplary embodiment of the premixed dual fuel burner depicting
the injection component at another second position as compared to
the first position depicted in FIG. 5 and the second position
depicted in FIG. 6, in accordance with the present technique.
DETAILED DESCRIPTION OF INVENTION
[0039] Hereinafter, above-mentioned and other features of the
present technique are described in details. Various embodiments are
described with reference to the drawing, wherein like reference
numerals are used to refer to like elements throughout. In the
following description, for purpose of explanation, numerous
specific details are set forth in order to provide a thorough
understanding of one or more embodiments. It may be noted that the
illustrated embodiments are intended to explain, and not to limit
the invention. It may be evident that such embodiments may be
practiced without these specific details.
[0040] It may be noted that in the present disclosure, the terms
"first", "second", "another second" etc. are used herein only to
facilitate discussion, and carry no particular temporal or
chronological significance unless otherwise indicated.
[0041] Referring to FIG. 1, a cross-sectional view of an exemplary
embodiment of a premixed dual fuel burner 1, hereinafter referred
to as the burner 1 has been schematically represented. The burner 1
essentially uses at least two main fuels a main gas fuel and a main
liquid fuel in addition to and besides a pilot fuel and associated
pilot fuel supply lines and techniques.
[0042] The burner 1 includes a burner head 10, a burner interior
20, a swirler 30, a premixing section 40 and an injection component
50. The burner 1 is assembled in association with a combustion
chamber 99 in a turbomachine (not shown) which work with dual fuel
combustion reaction. The main fuel is combusted in the combustion
chamber 99 in form of a combustion mixture after being mixed with
an air from a compressor section (now shown) of the turbomachine.
The main gas fuel mixed with air and the main liquid fuel may be
combusted in the combustion chamber 99 separately or
simultaneously.
[0043] The burner head 10 includes a burner head end 12. The
swirler 30 is arranged in series between the burner head 10 and the
premixing section 40. The burner 1 has a main axis 9. The burner
head 10, the swirler 30 and the premixing section 40 are arranged
along the main axis 9. The swirler 30 is an elongated 3-dimensional
body. When visualized as not integrated as a part of the burner 1,
the swirler 30 is open at both ends and has a side wall enclosing a
volume or limiting a volume within the side wall and the open ends.
Similarly, the premixing section 40 is an elongated 3-dimensional
body. When visualized as not integrated as a part of the burner 1,
the premixing section 40 is open at both ends and has a side wall
enclosing a volume or limiting a volume within the side wall and
the open ends.
[0044] However, when integrated as parts of the burner 1, and when
arranged in series such that the swirler 30 is positioned between
the burner head 10 and the premixing section 40, as depicted in
FIG. 1, the volume enclosed by swirler 30 and the volume enclosed
by the premixing section 40 together form a volume referred to as
the burner interior 20. The swirler 30 may be connected to the
burner head 10 by direct physical contact, as depicted in FIG. 1,
or may be connected to the burner head 10 through an intermediate
piece (not shown) or a connecting region (not shown). Similarly, in
the burner 1, the swirler 30 may be connected to the premixing
section 40 by direct physical contact with the premixing section 40
or may be connected to the premixing section 40 through an
intermediate connecting piece (not shown). The burner interior 20
represents a total volume enclosed by the swirler 30 and the
premixing section 40 with burner head 10 at one end of the total
volume and the combustion chamber 99 at the other end of the total
volume, either with or without one or more such intermediate
connecting pieces.
[0045] The burner interior 20 is a volume or a hollow that is
elongated along the main axis 9. The burner interior 20 is formed
of an upstream side 22 and a downstream side 24. The upstream side
22 is disposed between the burner head 10 and the downstream side
24. As depicted in FIG. 1, the upstream side 22 and the downstream
side 24 may be understood as a continuous volume, or in other
words, the upstream side 22 is fluidly connected to the downstream
side 24, i.e. the upstream side 22 and the downstream side 24 are
continuous and together form the burner interior 20 in FIG. 1. A
part of the burner interior 20 enclosed by the swirler 30 is the
upstream side 22 of the burner interior 20 and the other part of
the burner interior 20 enclosed by the premixing section 40 is the
downstream side 24 of the burner interior 20.
[0046] As depicted in FIG. 1, in an exemplary embodiment of the
burner 1, the swirler 30 is directly connected to or affixed to or
assembled with the burner head end 12 of the burner head 10, and
the swirler 30 is also directly connected to or affixed to or
assembled with the premixing section 40. As shown in FIG. 1, the
swirler 30 may be conically designed for example having a conical
frustum shape. The conical frustum shape of the swirler 30 has a
top side 36 and a bottom side 38. A cross-sectional area of the
bottom side 38 is greater than a cross-sectional area of the top
side 36, or in other words, a cross-section of the conical frustum
increases from the top side 36 towards the bottom side 38 along the
main axis 9. The top side 36 is connected to the burner head end 12
of the burner head 10 and the bottom side 38 is connected to the
pre-mixing section 40.
[0047] The swirler 30 includes an inlet section 32. The inlet
section 32 is fluidly connected to the compressor (not shown) of
the turbomachine (not shown). The inlet section 32 receives
compressed air from the compressor and introduces the compressed
air into the burner interior 20, more precisely into the upstream
side 22 of the burner interior 20. Similarly, the inlet section 32
is fluidly connected to a fuel supply (not shown) of the
turbomachine. The inlet section 32 receives main gas fuel from the
fuel supply and introduces the main gas fuel into the burner
interior 20, more precisely into the upstream side 22 of the burner
interior 20.
[0048] In an exemplary embodiment of the burner 1 as depicted in
FIG. 1, the inlet section 32 of the swirler 30 includes at least
one air inlet 33 and at least one main fuel gas inlet 34. The
compressed air is introduced into the burner interior 20 via the
air inlet 33 and the main gas fuel is introduced into the burner
interior 20 via the main fuel gas inlet 34. The air inlet 33 may be
tangentially arranged along the swirler 30 with respect to the main
axis 9. Similarly, the main fuel gas inlet 34 may be tangentially
arranged along the swirler 30 with respect to the main axis 9. For
example, when the swirler 30 is conical frustum shaped, the air
inlet 33 and/or the main fuel gas inlet 34 may be formed as
longitudinally extending slots through a body wall (now shown) of
the conical frustum. In an exemplary embodiment of the burner 1,
the inlet section 32 includes a plurality of the air inlets 33 and
a plurality of the main fuel gas inlets 34 arranged around the
swirler 30 in a distributed way such that when the main gas fuel
and the compressed air enter the burner interior 20 though the air
inlets 33 and the main fuel gas inlets 34, a swirl is generated in
the compressed air and the main gas fuel. Principle of swirl
generation through longitudinal slots i.e. the air inlets 33 and
the main fuel gas inlets 34, on such a conical shaped swirler 30 is
known in the art of turbomachines and thus not explained in details
herein for sake of brevity.
[0049] The premixing section 40 is an elongated tubular body. The
premixing section 40 has a burner outlet 42 through which the
premixing section 40 is arranged or fixed or assembled with the
combustion chamber 99. As seen in FIG. 1, in the burner 1 the
burner outlet 42 of the premixing section 40 is an opening through
which the burner interior 20, more precisely the downstream side 24
of the burner interior 20 fluidly connects to the combustion
chamber 99. Thus the burner interior 20 is continuous with the
combustion chamber 99 through the burner outlet 42. The combustion
mixture and/or its constituents flow from the swirler 30 into the
premixing section 40 and then into the combustion chamber 99 though
the burner outlet 42. The premixing section 40, also referred to as
mixer 40, performs or allows the mixing of the compressed air and
the main gas fuel.
[0050] The injection component 50 has a tapering structure
positioned along the main axis 9. The tapering structure of the
injection component 50 extends from the burner head 12 into the
burner interior 20. The injection component has a burner head side
52 and an injection side 54. The injection component 50 tapers from
the burner head side 52 to the injection side 54 along the main
axis 9. The tapering means a cross-sectional area perpendicular to
the main axis 9 of the injection component 50 decreases when moving
from the head side 52 to the injection side 54 along the main axis
9. In one embodiment the decrease in the cross-sectional area is
gradual for example when the injection body 50 is designed like in
form of a regular conical structure, as also depicted in FIG.
2.
[0051] The injection component 50 may be hollow for guiding fuel.
Particularly, as the injection component 50 is tapered, the inner
hollow space may also be tapered accordingly. So the fuel passage
within the injection component 50 reduces in width along an axial
direction of the tapered section of the injection component 50.
[0052] As seen in FIG. 1 in combination with FIG. 2, the injection
component 50 includes at least one liquid fuel outlet 55 at the
injection side 54. A main liquid fuel is introduced into the burner
interior 20 through the at least one liquid fuel outlet 55. The
main liquid fuel may be fed to the liquid fuel outlet 55 via fuel
lines (not shown) formed inside the injection body 50. The fuel
lines within the injection component 50 may in turn be connected to
a liquid fuel supply (now shown) of the turbomachine. As depicted
in FIG. 1, the injection side 54 of the injection component 50 is
disposed in the burner interior 20 as a free standing manner i.e.
without any physical supports at the injection side 54. As seen in
FIG. 1, the injection body 50, in an exemplary embodiment of the
burner 1, is coaxially positioned with the main axis 9.
[0053] As shown in FIGS. 1 and 2, the at least one liquid fuel
outlet 55 is at a side 58 of the injection side 54 of the injection
component 50. In an exemplary embodiment of the burner 1, there are
more than one liquid fuel outlets 55 located on the injection side
54 of the injection component 50, for example FIG. 1 shows two
liquid fuel outlets 55, from each of the liquid fuel outlets 55 the
main liquid fuel is discharged in form of a fluid stream or in
atomized form with a direction towards the combustion chamber 99,
for example as depicted by arrows 71. Furthermore, as depicted in
FIG. 2, the injection component 50 may include a second additional
outlet 62 which may have different shape or size as compared to the
liquid fuel outlet 55. The second additional outlet 62 is also used
to introduce the main liquid fuel into the burner interior 20,
albeit the second additional outlet 62 is at a different position
on the injection side 54 for example an end 56 of the injection
side 54 of the injection component 50.
[0054] Referring now to FIGS. 3 and 4 that schematically illustrate
a cross-sectional view of another exemplary embodiment of the
burner 1. As shown in FIGS. 3 and 4, the at least one liquid fuel
outlet 55 is at an end 56 of the injection side 54 of the injection
component 50. In an exemplary embodiment of the burner 1, there may
be more than one liquid fuel outlets 55 located on the end 56 of
the injection side 54 of the injection component 50. FIG. 3 shows
one liquid fuel outlet 55 from which the main liquid fuel is
discharged in form of a fluid stream or in atomized form with a
direction towards the combustion chamber 99, for example as
depicted by arrow 71. Furthermore, as depicted in FIG. 4, the
injection component 50 may include a first additional outlet 61
which may have different shape or size as compared to the liquid
fuel outlet 55. FIG. 4 depicts two such first additional outlets
61. The additional outlet 61 is also used to introduce the main
liquid fuel into the burner interior 20, albeit the first
additional outlet 61 is at a different position on the injection
side 54 for example a side 58 of the injection side 54 of the
injection component 50.
[0055] As can be seen in FIGS. 1 and 3, in both embodiments of the
burner 1, due to the tapering structure of the injection component
50 which aids in the axial flow of the air from the compressor
and/or combustion mixture along the main axis 9 and due to
injection of the main liquid fuel via the liquid fuel outlet 55 in
a suitable position within the downstream side 24 of the burner
interior 20, formation of a central recirculation zone 4 in the
combustion chamber 99 is achieved, and undesired formation of any
recirculation zone extending into the burner interior 20 is
obviated.
[0056] Furthermore, as seen in FIGS. 1 and 3, in the burner 1, the
premixing section 40 has a part 44 of the premixing section 40 that
surrounds the burner outlet 42 of the premixing section 40. The
part 44 includes an external pilot 45, as depicted in FIG. 1. From
the external pilot 45, a pilot fuel is introduced into the
combustion chamber 99. FIGS. 1 and 3 show introduction of the pilot
fuel through the part 44 into the combustion chamber 99. A
direction of injection of the pilot fuel is depicted by arrow 72 in
FIGS. 1 and 3. It may be noted that though FIG. 1 shows just one
external pilot 45, it is well within the scope of the present
technique that a plurality of the external pilots 45 are present
distributed circumferentially around a body (not shown) of the
premixing section 40 around the burner outlet 42.
[0057] As depicted in FIGS. 1 and 3, in both embodiments of the
burner 1, due to the external pilot 45 and the ejection of the
pilot fuel from the external pilot 45 in the direction 72,
formation of an external recirculation zone 5 in the combustion
chamber 99 is achieved. In exemplary embodiment of the burner 1,
the external recirculation zone 5 surrounds the central
recirculation zone 4 annularly and helps to further stabilize the
central recirculation zone 4.
[0058] Now referring to FIGS. 5, 6 and 7, different positions of
the injection component 50 along the main axis 9 are depicted. As
seen in FIG. 5, in an embodiment of the burner 1, the liquid fuel
outlet 55 is positioned in the downstream side 24 of the burner
interior 20. Similarly, as seen in FIG. 6, in another embodiment of
the burner 1, the liquid fuel outlet 55 is positioned in the
downstream side 24 of the burner interior 20 albeit in a different
position with respect to the position of the liquid fuel outlet 55
of FIG. 5. Alternatively, as seen in FIG. 7, in an alternate
embodiment of the burner 1, the liquid fuel outlet 55 is positioned
in the upstream side 22 of the burner interior 20.
[0059] As depicted in FIGS. 1, 3 and 5, a first distance 91 is a
distance along the main axis 9 between the at least one liquid fuel
outlet 55 and the burner head end 12, and a second distance 92 is a
distance along the main axis 9 between the burner outlet 42 of the
premixing section 40 and the burner head end 12. In embodiments of
the burner 1, where there are more than one liquid fuel outlets 55,
the first length 91 is calculated as a mathematical average of all
the distances of each individual liquid fuel outlets 55 from the
burner head end 12. In other embodiments of the burner 1, as
depicted in way of exemplary embodiments of FIGS. 5, 6 and 7
mainly, a ratio of the first distance 91 and the second distance 92
may vary, for example the first distance 91 may be between 20% and
80% of the second distance 92 along the main axis 9.
[0060] Furthermore, in one embodiment of the burner 1, the
injection component 50 is longitudinally adjustable or moveable
along the central axis 9, such that a position of the at least one
liquid fuel outlet 55 of the injection component 50 gets changed
from a first location 93, as depicted in FIG. 5 along the main axis
9 to a second location 94 along the main axis 9, as depicted in
FIG. 6. Thus the injection component 50 is retractable into the
burner interior 20 from the combustor chamber outlet 42 towards the
burner head 10 and/or is extendable into the burner interior 20
from burner head 10 towards the combustor chamber outlet 42.
[0061] Furthermore, as depicted from a combination of FIGS. 5, 6
and 7, it can been seen that the injection component 50 has
progressively retracted into the burner interior 20 from the
combustor chamber outlet 42 towards the burner head 10 gradually
from FIGS. 5 to 7. FIG. 7 shows another second location 94 depicted
in FIG. 7 as compared to the second location 94 of FIG. 6 and as
compared to the first location 93 of FIG. 5.
[0062] The shape of a fuel lance--i.e. the injection component
50--is tapered in a way, that the fuel lance is an elongated
component. Advantageously it may reduce its width taken in radial
direction along an axial distance D only by or less than D/10,
advantageously less than D/20.
[0063] While the present technique has been described in detail
with reference to certain embodiments, it should be appreciated
that the present technique is not limited to those precise
embodiments. Rather, in view of the present disclosure which
describes exemplary modes for practicing the invention, many
modifications and variations would present themselves, to those
skilled in the art without departing from the scope and spirit of
this invention. The scope of the invention is, therefore, indicated
by the following claims rather than by the foregoing description.
All changes, modifications, and variations coming within the
meaning and range of equivalency of the claims are to be considered
within their scope.
* * * * *