A PREMIXED DUAL FUEL BURNER WITH A TAPERING INJECTION COMPONENT FOR MAIN LIQUID FUEL
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.
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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 INVENTIONThe present invention relates to turbomachine components and more particularly to a burner for a dual fuel based combustion chamber for a turbomachine.
BACKGROUND OF INVENTIONIn 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 NOX 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.
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.
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.
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.
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.
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.
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 INVENTIONAn 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.
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.
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.
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.
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.
The injection component is particularly a fuel lance.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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 NOx combustions.
The present technique is further described hereinafter with reference to illustrated embodiments shown in the accompanying drawing, in which:
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.
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.
Referring to
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.
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.
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
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
As depicted in
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.
In an exemplary embodiment of the burner 1 as depicted in
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
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
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.
As seen in
As shown in
Referring now to
As can be seen in
Furthermore, as seen in
As depicted in
Now referring to
As depicted in
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
Furthermore, as depicted from a combination of
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.
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.
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.
Type: Application
Filed: Jul 29, 2016
Publication Date: Aug 2, 2018
Applicant: Siemens Aktiengesellschaft (Munich)
Inventors: Nicklas Johansson (Skärblacka), Thomas Lindgren (Norrköping), Magnus Persson (Svärtinge)
Application Number: 15/747,502