Patent Application
20110113784
This application claims priority of European Patent Office application No. 09014417.1 EP Filed Nov. 18, 2009, which is incorporated by reference herein in its entirety.
The present invention relates to a swirler vane for providing fuel, particularly liquid fuel, to a swirling zone of a burner assembly, comprising at least one injection hole for injecting the fuel to the swirling zone of the burner and an injection feed hole connecting the at least one injection hole with a main fuel feed. The invention relates further to a swirler, comprising a plurality of swirler vanes, and to a burner assembly, in particular of a gas turbine engine.
Air pollution is a worldwide concern and many countries have enacted stricter laws for further limiting the emission of pollutants from gas turbine engines or offer fiscal or other benefits for environmentally sound installations.
Although the prior techniques for reducing the emissions of NOX from gas turbine engines are steps in the right direction, the need for additional improvements remains.
The main purpose of a burner assembly of a gas turbine engine is to mix fuel with air to obtain stable and efficient combustion with good flame stability and the smallest possible amount of NOX emissions. Therefore, the burner assembly design must ensure that proper amounts of fuel are introduced in the right locations within the burner fuel vaporization takes place.
To achieve low emissions the combustion efficiency for fuel has to be improved. This can be achieved, for example, by a good atomization and a good vaporization of liquid fuel, whereby better atomization allows more vaporization.
Usually the premixing of liquid fuel and air in a gas turbine engine takes place by injecting liquid fuel into an air stream in a swirling zone of the burner assembly which is located upstream from the combustion zone of the burner assembly. The swirling produces a mixing of liquid fuel and air before the mixture enters the combustion zone. The better the mixing of liquid fuel and air and the better the vaporization of the liquid fuel the less emissions can be achieved.
Swirlers may be provided to gain better mixing of fuel and air. Swirlers are comprised of swirler vanes defining swirl slots, arranged in such a way that air, into which fuel is injected, will start a rotational movement which results in a better fuel and air mixture. Liquid fuel provided by a main liquid fuel feed will be injected into the air stream through injection feed holes. The swirler vanes are guiding the air flow, enriched by the fuel, into a combustion zone. The liquid fuel is further atomised by the use of a nozzle positioned on the base of the injection hole or the swirl slot. One disadvantage of the nozzle is that it injects the fuel in a non optimised location due to the mechanical constraints of the system.
An object of the present invention is to provide an improved swirler vane, an improved swirler and an improved burner assembly, which enable a good fuel and air mixing—particularly the mixing of liquid fuel and air—and which reduce the emissions of the burner assembly of a gas turbine. Furthermore an improved serviceability of a swirler and a burner assembly is desired.
The objective is achieved by a swirler vane with the features according to the claims, by a swirler with the features according to the claims, and by a burner assembly with the features according to the claims. Advantages, features, details, aspects and effects of the invention arise from the dependent claims, the description and the figures. Features and details which are described in connection with the swirler vane count as well for the swirler and the burner assembly, and vice versa.
According to a first aspect of the present invention the objective is achieved by a swirler vane for providing fuel, particularly liquid fuel, to a swirling zone of a burner assembly, comprising at least one injection hole for injecting the fuel to the swirling zone of the burner assembly and an injection feed hole passages—particularly comprising a section in form of a gallery—connecting the at least one injection hole with a main fuel feed, whereby the swirler vane or a tip of the swirler vane, where the at least one injection hole is arranged, is being manufactured—i.e. built up—by laser deposition or comprises at least a surface being manufactured by laser deposition.
The swirler vane or a tip of the swirler vane is built up using laser deposition. One advantage of such a laser deposition grown swirler vane or such a tip of the swirler vane is that the heat treatment during the laser deposition relaxes stresses due to thermal expansion mismatch in the swirler vane, in particular between the swirler vane and the film, since growth occurs at high temperatures, around about 800° C. The design and shape of a swirler vane or a tip of a swirler vane can be influenced very exactly. The swirler itself can be made using conventional machining methods. In order to allow the fuel—particularly liquid fuel—to be injected at the tip of the swirler vane at least a portion of the tip is built up using laser deposition.
Laser deposition or pulsed laser deposition is a thin film deposition technique where a high power pulsed laser beam is focused inside a vacuum chamber to strike a target of a desired composition. Thereby material is vaporized from the target and deposited as a thin film on the swirler vane and the wall of the injection hole and/or the injection feed hole passages inside the swirler vane, respectively. Such a swirler vane or such a tip of a swirler vane is very heat resistant. The friction resistance of the injection hole and/or the injection feed hole is decreased by a laser depositioned surface. Therefore the fuel can be guided through the injection feed hole passages and/or the injection hole much more accurate. A swirler vane or the tip of a swirler vane which are built up using laser deposition can accurately control the fuel being injected. A swirler vane like that can improve the fuel and air mixing. The fuel can be injected very accurately into the swirler shear layer. Such a swirler vane can reduce the emissions of the burner assembly.
One swirler vane can have two or more injections holes, if desired.
Therefore, in a preferred embodiment of the swirler vane, the swirler vane is characterized in that the wall of the at least one injection hole is being manufactured—i.e. built up or formed—by laser deposition. Additional or alternative to that a swirler vane is preferred whereby at least a part of the injection feed hole passages, which end in the at least one injection hole, is being manufactured by laser deposition.
Preferred is further an embodiment of the swirler vane, whereby the swirler vane is shaped as a pie slice. For example, the swirler vanes can be of a pie slice type with substantially triangular footprints and rectangular side faces and a slightly curved outer surface. The tips of the swirler vane, where the at least one injection hole is arranged, are directed to the swirling zone of the burner assembly.
The shape of the at least one injection hole can vary. The injection hole can take whatever shape for good mixing, as it is formed using laser deposition. In a preferred embodiment of the swirler vane the at least one injection hole of the swirler vane has a rectangular, a circular, a polygonal, an oval or a triangular shape. The at least one injection hole of the swirler vane can be shaped like a slot. The injection hole or holes can be located on either the pressure or suction side or on both sides of the swirl slot in order to give optimised mixing.
Preferred is further an embodiment of the swirler vane, whereby the swirler vane is characterized in that a perforated plate, which comprises one or several holes, is being placed into the at least one injection hole. Such a perforated plate can be placed into the laser deposited injection hole to give a very fine control of the fuel—particularly of liquid fuel—being injected to the swirling zone of the burner assembly. In particular a pre calibrated micro laser drilled plate can be placed into the injection holes of each laser deposited swirler tip, to give fine control of the fuel being injected to the burner assembly.
According to a second aspect of the invention the objective is achieved by a swirler, in particular a swirler of a burner assembly of a gas turbine engine, comprising a plurality of swirler vanes according to the first aspect of the invention. A swirler with a plurality of swirler vanes, which are built for providing fuel, particularly liquid fuel, to a swirling zone of a burner assembly, comprising at least one injection hole for injecting the fuel to the swirling zone of the burner assembly and injection feed hole passages—particularly an injection feed hole gallery—connecting the at least one injection hole with a main fuel feed, particularly for liquid fuel, whereby the swirler vane or a tip of the swirler vane, where the at least one injection hole is arranged, is being manufactured by laser deposition or comprises at least a surface being manufactured by laser deposition, can improve the mixing of the fuel and air in the swirling zone, which is placed upstream the combustion zone of the burner assembly. The flow of the fuel through the injection holes and the injection feed holes passages can be increased and better controlled, respectively. The mixing of the fuel with air can be improved by injection of the fuel into the swirler shear layer. Such a swirler can reduce the emissions of the burner assembly of the gas turbine engine.
In a preferred embodiment of the swirler, the swirler is characterized in that the swirler vanes build a first part of overall swirler vanes, whereby a second part of the overall swirler vanes comprise at least one second injection hole for injecting gaseous fuel to the swirling zone of the burner assembly and second injection feed hole passages connecting the at least one second injection hole with a main gaseous fuel feed. Advantageously the first parts of the overall swirler vanes build an inner swirler and the second part of the overall swirler vanes build an outer swirler. The swirler can be split into two parts, namely an inner swirler and an outer swirler. The inner swirler is responsible for the liquid fuel supply from the main liquid fuel inlet to the swirling zone of the burner. The outer swirler is responsible for the air supply from the air inlet to the swirling zone of the burner assembly. The outer swirler is furthermore responsible for the gaseous fuel supply from the main gaseous fuel inlet to the swirling zone of the burner assembly. The swirler is built modular. In a mounted position the two swirler parts are fixed in such a way that the swirler vanes, which are part of the inner swirler, and the swirler vanes, which are part of the outer swirler, build overall vanes. These overall vanes are preferably shaped as a pie slice. The inner swirler may be formed in pie slice form itself and may form the tip of the overall pie sliced vanes, once assembled. Walls of the vanes of the inner swirler part and walls of vanes of the outer swirler part will be aligned when mounted to gain the overall pie slice form. The pie slice shape of the two part together then, during operation, provide the feed of the air and the fuel/air mixture to the combustor. This modularization of the swirler components results in an improved serviceability.
In other words, the invention is also directed to a swirler comprising a plurality of swirler vanes positioned radially around a central axis of the swirler and a plurality of mixing channels for mixing fuel and air, characterized in that the swirler being assembled from a first swirler piece and a separate second swirler piece, the first swirler piece comprises a first platform on which a plurality of first sections of the plurality of swirler vanes is attached and the second swirler piece comprises a second platform on which a plurality of second sections of the plurality of swirler vanes is attached. The swirler being assembled such as the plurality of first sections form a downstream section of walls of the mixing channels and the plurality of second sections form an upstream section of the walls of the mixing channels. Thus, the two separate pieces can be manufactured separately and provide a modular layout of the swirler. This is advantageous because only the first piece or only the second piece may be replaced during service. The first and the second piece will be assembled in such a way that the form mixing channels with walls in which the downstream section of the walls are a direct continuation of the upstream section of the walls, such as the downstream section of a specific wall lies in the same plane as the upstream section of the wall. Advantageously, as indicated before, the first piece will define an inner region of the swirler and the second piece will define an outer region of the swirler. Preferably, the first piece will be in shape of a circle with an outer radius R and the second piece will be in a torus-like shape, with an inner radius having the same radius R as the outer radius of the first piece.
The pilot burner and the adaptor plate, which fixed the swirler parts, can be retained compared to a known burner assembly of gas turbine engine. Only the swirler differs to the known burner assemblies of gas turbine engines. The two swirler elements, namely the inner and the outer swirler, can be made using conventional machining methods. In order to allow the fuel—particularly liquid fuel—to be injected at the tip of each swirler vane a portion of the tip is built up using laser deposition.
According to a third aspect of the invention the objective is achieved by a burner assembly, in particular of a gas turbine engine, comprising a swirler according to the second aspect of the invention. A burner assembly with a swirler comprising a plurality of swirler vanes according to the first aspect of the invention can improve the mixing of the fuel and the air in the swirling zone of a burner assembly. That means, a burner assembly with a swirler with a plurality of swirler vanes, which are built for providing fuel to a swirling zone of a burner, comprising at least one injection hole for injecting the fuel to the swirling zone of the burner assembly and injection feed hole passages connecting the at least one injection hole with a main fuel feed, whereby the swirler vane or a tip of the swirler vane, where the at least one injection hole is arranged, is being manufactured by laser deposition or comprises at least a surface being manufactured by laser deposition, can improve the mixing of the fuel and the air in the swirling zone, which is placed upstream the combustion zone of the burner assembly. The flow of the fuel through the injection holes and the injection feed hole galleries can be increased. Such a burner assembly can reduce the emissions of the gas turbine engine.
In a preferred embodiment the burner assembly is characterized in that the inner swirler is fixed to a main liquid fuel inlet, which comprises the main liquid fuel feed. The inner swirler can be fixed friction locked and/or material locked at the main liquid inlet of the burner assembly. The outer swirler can be fixed friction locked and/or material locked at the adapter plate of the burner assembly.
Even though in some incidents specifically liquid fuel is referred to, the inventive concept also applies, without limitation, to a feed with gaseous fuel or even both types of fuel.
Further features, properties and advantages of the present invention will become clear from the following description of embodiments of the invention in conjunction with the accompanying drawings, which shown schematically.
Elements with the same function and mode of operation are provided in the
In
Such a swirler improves the liquid fuel and air mixing by injection of liquid fuel into the swirler shear layer. As result of the improved liquid fuel and air mixing the emissions from a gas turbine, in which the burner assembly is arranged, can be reduced. Another advantage is the improved serviceability through the modularisation of the components, in particular the swirler 2.
The invention can split for example an existing swirler into two swirler parts 2a, 2b. That means the liquid fuel injections is part of the inner swirler 2a and the air injection is part of the outer swirler 2b. The pilot burner 1 and adaptor plate 9 can be retained in the existing swirler layout, the inner swirler 2a and the outer swirler can be interchanged with the existing swirler.
The two swirler elements 2a, 2b are made using conventional machining methods. In order to allow the liquid fuel to be injected at the tip 20a of the swirler vane 10a of the inner swirler 2a the tip 20a or a portion of the tip 20a is built up using laser deposition.
The injection holes 11 can take whatever shape for good mixing, as they are formed using laser deposition. They could be for example rectangular, circular, square or triangular with a single or multiple point of injection. They can be located on either the pressure or suction side, or at both sides, of the injection holes 11, in order to give optimised mixing.
Advantages gained by the invention are the improved fuel mixing, the interchangeable with existing burner assemblies, the reduction in engine emissions, the improved turndown capability and the accurate control of fuel being injected.
It has to be noted that the discussed embodiments are not restricted to a feed with liquid fuel. Gaseous fuels may alternatively or additionally be provided for the inventive burner assembly, swirler, or swirler vane.
| Number | Date | Country | Kind |
|---|---|---|---|
| 09014417.1 | Nov 2009 | EP | regional |
