EP1526332A2 - Fuel injection nozzle - Google Patents

Abstract

Fuel injection nozzle comprises a film support (1) containing several fuel openings (2) having a middle axis (5) arranged parallel to the main flow direction (6, 7). Preferred Features: The middle axis of the openings are arranged at an acute angle to the flow direction of the air close to the wall.

Description

The invention relates to a fuel injector according to the features of the preamble of the main claim.

More particularly, the invention relates to a fuel injector for a gas turbine combustor with a film former, on which a plurality of fuel openings formed are.

Mixture preparation of fuel and air in gas turbine combustion chambers takes place in very different ways and leaves basically with regard to their use for inpatient Gas turbines or aircraft gas turbines and thus in terms of different Differentiate requirements. To reduce pollutant emissions, mainly nitrogen oxide emissions, However, the fuel generally needs to be as much air as possible be premixed to a lean one characterized by excess air Set combustion state. This mixture is problematic as it stabilizes by burning May affect mechanisms.

Fig. 1 shows a schematic side sectional view of a Combustion chamber 10 with associated fuel injection. shown is a central feeder of fuel in the Burner axis 22 and a decentralized supply of fuel 23 almost perpendicular to the burner axis. By the arrows 11 and Figure 12 is a schematic view of the supply of air to a inner swirler 14 and an outer swirler 15 are shown. The fuel-air mixture 13 flows in a known manner in the combustion chamber 10 a.

The stabilization of the combustion takes place almost exclusively with air swirl, which is a recirculation of partially combusted gases allows. The fuel is often centrally through a nozzle introduced, which mounted on the center axis of the atomizer is. The fuel is often with considerable Overpressure injected into the air flow enough to Penetration to achieve and as much air with fuel to be able to premix. These pressure atomizers have to one the function to directly atomize fuel. For some Designs of an injector but should the fuel sprayed as completely as possible on a nebulizer lip become. The fuel gets through the air on a nebulizer lip accelerated and at the downstream end of this lip Torn into small drops and mixed with the air. A another way of putting the fuel on this nebulizer lip to raise, consists with a so-called film depositor, wherein Fuel is distributed as uniformly as possible in a film.

Another way of keeping the fuel as intense as possible to mix with a large part of the air, consists in one decentralized injection (Fig. 2) from the outer boundary a flow channel formed by a film feeder 1, which the majority of the air leads. This can be from a nebulizer lip or else from the outer nozzle contour. This injection is characterized in that, different as with a film-maker, the fuel is one defined Penetration into the main air flow should learn.

Both the fuel injection with central nozzle or Druckzerstäuber, as well as a application as a film on one Filmleger, are to be optimized so that as much as possible The air flowing through the atomizer homogeneous with fuel is mixed before combustion. Characteristic of the low-emission, low-NOx combustion is one lean super-mixed fuel preparation with air excess. The consequence is fuel nozzles, the large flow cross sections possess to premix the high proportion of air with fuel to be able to. Due to the size of these fuel nozzles and the limited fortune of fuel jets and - sprays, in a central injection the ever-growing Air ducts to penetrate and thus a homogeneous distribution to achieve the fuel-air mixture are novel Concepts of fuel injection and premixing required.

The homogeneous distribution and introduction of the fuel in large air flow channels require a decentralized injection from as many fuel holes as possible to the Flow walls of the air flow must be arranged. A high number has the consequence that these openings very are small, resulting in blockages or blockages by Can lead to fuel contamination. Because these burners often can be switched on at higher loads of the engine can a blockage also by decomposition products of the fuel be caused, if after previous medium or High load operation of burner operation through these fuel ports is turned off and in the fuel nozzle remaining fuel is heated and decomposed.

The fuel nozzles are often through one in the radial direction very uneven velocity and mass flow distribution characterized. Due to the swirl of the air, which needed to stabilize the subsequent combustion is, the local air mass flow in the area of the radial outer boundary wall largest. Is the fuel out a few openings introduced into the flow, on the one hand the homogeneity of the fuel in the air in the circumferential direction impaired, on the other hand, the fuel can be very penetrate deeply into the flow and thus unintentionally in Regions mix and vaporize where not sufficient Air is available. This can also be done with a decentralized Injection occur.

The invention is based on the object, a fuel injector to create the type mentioned, which at simple construction and reliable operation a uniform Mixing of fuel and air ensured.

According to the invention, the object is achieved by the feature combination of the main claim, the dependent claims show further advantageous embodiments of the invention.

According to the invention it is thus provided that the central axes the fuel holes by the film layer with respect to their radial alignment substantially parallel to the main flow direction the air are arranged. This essentially Parallel arrangement can also be up to a range of the absolute Diverge in parallelism through an acute angle is marked. Purely for structural reasons, it is not always possible, the fuel injection completely parallel perform. According to the invention, it is important that the fuel injection has a high axial component and the fuel thus not injected radially.

The fuel openings may be on a radially inner wall The filmmaker can be created, but you can also at a Leave the rear edge of the same.

The film-maker or the area of injection of the fuel is preferably arranged between two swirlers.

It is particularly advantageous if the fuel openings in addition are inclined in the twisting direction of the air, i. an additional Have circumferential component. This can be in the same direction or be formed in the counter-twist. Furthermore, it is according to the invention possible, the fuel ports single row, multi-row, to arrange flush with each other or staggered to each other.

According to the invention, the film-maker can also be designed like a lamella be to even better mixing of the air-fuel mixture to reach.

Fig. 1

eine schematische Darstellung eines Längsschnitts durch eine erfindungsgemäße Gasturbinenbrennkammer,

Fig. 2

eine Kraftstoffdüse mit dezentraler, nach innen gerichteter Kraftstoffeinspritzung nach dem Stand der Technik mit entsprechender Verdeutlichung des Details,

Fig. 3

eine erste erfindungsgemäße Ausgestaltungsform einer Kraftstoffdüse mit dezentraler Einspritzung mit strömungsgerichteter Kraftstoffeindüsung in analoger Darstellung zur Fig. 2,

Fig. 4

ein weiteres Ausführungsbeispiel einer Kraftstoffdüse mit dezentraler Einspritzung mit Kraftstoffeindüsung an der Hinterkante eines Filmlegers, ebenfalls in analoger Darstellung zu den Fig. 2 und 3,

Fig. 5

eine stirnseitige Schnittansicht in Richtung der Pfeile A, B und C der Fig. 2 bis 4, darstellend die Kraftstoffeinspritzung im Gleichdrall zur Luftströmung,

Fig. 6

eine Darstellung analog Fig. 5 mit Darstellung der Kraftstoffeinspritzung im Gegendrall zur Luftströmung,

Fig. 7

eine Teil-Seitenansicht, analog Fig. 4,

Fig. 8

den Verlauf der Axialgeschwindigkeit der Luft über einer lokalen Koordinate x, die den axialen Abstand von der Hinterkante der Kraftstoffeinspritzdüse angibt,

Fig. 9

eine verdeutlichende Darstellung, analog Fig. 7, zur Erläuterung der Fig. 10 und 11,

Fig. 10

eine Ansicht in Pfeilrichtung D von Fig. 9 zur Darstellung der äußeren und der inneren Luftverdrallung sowie der Verdrallung des Kraftstoffs im Gleichdrall,

Fig. 11

eine Darstellung, analog Fig. 10, bei einer Eindüsung des Kraftstoffs im Gegendrall zur Luftströmung,

Fig. 12

eine verdeutlichende Ansicht zur Darstellung der Abbildungen der Fig. 13 und 14,

Fig. 13

eine Ansicht in Richtung des Pfeils D gemäß Fig. 12 zur Darstellung einer einreihigen Anordnung von Kraftstoffbohrungen,

Fig. 14

eine analoge Darstellung zur Fig. 13 mit gestaffelter Anordnung der Kraftstoffbohrungen,

Fig. 15

eine weitere Ausgestaltungsvariante mit einer lamellenartigen Ausführung der Filmlegeroberfläche.

In the following the invention will be described by means of embodiments in conjunction with the drawing. Showing:

Fig. 1

FIG. 2 a schematic representation of a longitudinal section through a gas turbine combustion chamber according to the invention, FIG.

Fig. 2

a fuel nozzle with decentralized, inwardly directed fuel injection according to the prior art with corresponding clarification of the details,

Fig. 3

a first embodiment of a fuel nozzle according to the invention with decentralized injection with flow-oriented fuel injection in an analogous representation to Fig. 2,

Fig. 4

2 shows a further exemplary embodiment of a fuel nozzle with decentralized injection with fuel injection at the trailing edge of a film applicator, likewise analogous to FIGS. 2 and 3;

Fig. 5

4 is an end sectional view in the direction of the arrows A, B and C of FIGS. 2 to 4, illustrating the fuel injection in the same direction to the air flow,

Fig. 6

a representation analogous to FIG. 5 with representation of the fuel injection in the counter-rotation to the air flow,

Fig. 7

a partial side view, analogous to FIG. 4,

Fig. 8

the course of the axial velocity of the air over a local coordinate x, which indicates the axial distance from the rear edge of the fuel injection nozzle,

Fig. 9

an explanatory illustration, analogous to FIG. 7, for explaining FIGS. 10 and 11,

Fig. 10

a view in the direction of arrow D of Figure 9 showing the outer and the inner Luftverdrallung and the twisting of the fuel in the co-rotating,

Fig. 11

a representation, analogous to FIG. 10, with an injection of the fuel in the counter-rotation to the air flow,

Fig. 12

3 is an explanatory view illustrating the illustrations of FIGS. 13 and 14;

Fig. 13

a view in the direction of arrow D of FIG. 12 showing a single-row arrangement of fuel holes,

Fig. 14

an analogous representation of Figure 13 with staggered arrangement of the fuel bores,

Fig. 15

a further embodiment variant with a lamellar design of the film applicator surface.

In the figures, the same parts are each given the same reference numerals Mistake.

Fig. 3 shows a simplified representation of a section by the film applicator 1 according to the invention, wherein fuel openings 2, in particular fuel bores 3, shown are whose center axes 5 by an angle α to the main flow direction 6 (wall-near flow direction in the inner swirl duct) are inclined.

The reference numeral 16 shows a hired wall element of Filmlegers 1, the reference numeral 17 shows an aerodynamic adapted film layer surface. With the reference numeral 21 is a fuel line shown.

The invention avoids the unwanted intrusion of the liquid Fuel in areas with low flow rates and the associated uneven fuel-air mixture. A proposed embodiment is shown in FIG. 3 shown. The fuel is here at a film layer not radially inward, i. with a high radial component the exit velocity of the fuel into an inner Injected swirl channel. Rather, in the proposed concept a high axial component of the exit velocity the fuel is present and the fuel is approaching parallel to the main flow direction of the inner swirl duct brought in. In Fig. 3 are schematically the fuel ports as well as the Ausdüsung of the fuel shown.

The fuel is initially through the openings shown over a hired against the air flow direction Angle α injected, which is formed as an acute angle. In addition, the fuel openings in the circumferential direction arranged in the same or counter-rotation to the air flow be. By hiring the number of fuel holes be reduced, at the same time also the penetration depth controlled, since the regions high air speed and thus high local air mass flows near the wall the outer wall of the twisted air flow occur. Of the liquid fuel gets after a short run length the Ausdüsung on the surface of a hired wall element of the filmmaker, on which a distribution or film formation takes place of the fuel in the axial and circumferential direction (see Fig. 3). Due to the high flow acceleration near the wall of the filmmaker becomes the educating one Fuel film continues downstream near the boundary layer of the following Contour of the filmmaker held. By an aerodynamic favorable i. Low-loss design of the film-forming geometry before the exit holes of the fuel, thus finds already from the injection point of the fuel mixing with the twisted air instead. In addition, the Flow acceleration of the air exploited to prevent penetration of unevaporated fuel droplets in the direction of the burner axis to avoid. In contrast to the previously known Fuel nozzles with decentralized injection (see Fig. 2) can according to the invention the formation of an undisturbed itself along the film layer developing fuel film ensures become. For structural reasons, the in Fig. 3 embodiment designed as a split design be. The shape of the openings can also be different be executed, i. round, elliptical, etc. By the invention Construction will be the development of a fuel film in a radially very limited flow layer guaranteed. At the trailing edge of the filmmaker rips the Fuel film decreases and is accelerated by the presence of and twisted air from the outer and inner Flow channel homogeneously mixed.

Another embodiment of the invention provides the injection of the fuel at the trailing edge of a flow divider between two swirlers before (Fig. 4). The speed maxima the accelerated and twisted in the swirl generator Air is near the wall of the formed flow divider, i.e. in the outer flow of the boundary layer both sides of the flow divider. In the wake of the flow divider finds a continuous acceleration of the air at high Luftverdrallung instead. Figs. 7 and 8 show the axial acceleration of the flow in the wake of the trailing edge of the flow divider, where x is the axial distance from the trailing edge of the flow divider is. Have CFD exams shown that with this embodiment a very homogeneous Fuel-air mixture in the wake area of the flow divider can be achieved, the fuel in accelerated axially Flow areas is introduced. On average Low temperatures can be very low nitrogen oxide emissions to reach. The main feature of this embodiment is the avoidance of significant radial velocity components of the injected fuel, allowing penetration of individual drop classes in the vicinity of the burner axis, i.e. in areas with low flow velocities, is avoided in principle. By the training Shear layer between the twisted air flows takes place at high relative speeds between fuel and Air a very intense mix. Different injection variants are shown in Figs. 9 to 14. The injection of the fuel can be both in the DC and counter-rotating take place to the inner or outer air swirl. Furthermore The arrangement of the fuel bores can both single row as well as multi-row, aligned as well as staggered to each other be arranged.

Another embodiment of the invention provides a lamellar Shaping the filmmaker before. In Fig. 15 is to schematically illustrated a variant of the filmmaker. On the basis to the low-loss design of the exhaust gas mixer a Aero engine is aimed at different mass air flows To bring together loss as possible to a total flow. The mixture should be in the proposed burner concept however, to an improved mixture formation by a three-dimensional mixing of a twisted air stream with a partially premixed with air fuel flow to lead. The twisted air from the outer channel periodically penetrates into the inner channel through the shaping one. With an injection of the fuel in the inner or outer Spinal canal develops as the residence time increases downstream of the coater a fuel-air mixture. This Mixture may also be due to the shaping in the inner Penetrate swirl channel. Within a suitable "deflection" s up to ± 15% of the nominal centerline of the trailing edge The film layer can thus produce a flow layer be in a very intense mixture of the fuel-air mixture from the inner canal and pure air mixing can be done from the outer swirl duct or vice versa. In order to can be a very homogeneous mixture produce, the uniform temperature field with low absolute temperatures and low nitrogen oxide levels. Another feature the embodiment shown in Fig. 15 can also be a Flange-adapted spiral geometry of the lamellar film layer be in which the lamellar geometry correspondingly effective adapted to the air swirl near the wall of the filmmaker.

The advantage of the invention is thus a practice-relevant solution the problem of premixing fuel homogeneously with air and this with as few, relatively large fuel ports a defined and not too large penetration depth of the Fuel into the air flow to achieve. Overall goal is the reduction of nitrogen oxide ejection of the gas turbine combustor with a robust and technically feasible fuel injection configuration.

LIST OF REFERENCE NUMBERS

1

film applicator

2

Fuel opening

3

Fuel hole

4

Fuel direction

5

Center axis of the fuel ports

6

Near-wall main flow direction (inner swirl channel)

7

Near-wall main flow direction (outer swirl channel)

8th

Air swirl (inner swirl channel)

9

Air swirl (outer swirl channel)

10

combustion chamber

11

Air supply (inner swirl duct)

12

Air supply (outer swirl duct)

13

Air / fuel mixture

14

Inner swirler

15

Outer swirler

16

wall element

17

Film applicator surface

18

Outer swirl duct (air)

19

Inner swirl duct (air)

20

Film applicator surface

21

Fuel line

22

Fuel supply (central)

23

Fuel supply (decentralized)

24

Lamellar film-maker

Claims (13)

A fuel injector for a gas turbine combustor, comprising a film former (1) in which a plurality of fuel ports (2) are formed, characterized in that the center axes (5) of the fuel ports (2) are substantially parallel to the radial direction due to the film former (1) Main flow direction (6) and (7) of the air are arranged. Fuel injection nozzle according to claim 1, characterized in that the center axes (5) of the fuel openings (2) are arranged with respect to their radial orientation at an acute angle to the wall-near flow direction of the air. Fuel injection nozzle according to claim 1 or 2, characterized in that the fuel openings (2) are arranged on a radially inner wall of the film applicator. Fuel injection nozzle according to claim 1 or 2, characterized in that the fuel openings (2) are arranged on a radially outer wall of the film applicator. Fuel injection nozzle according to claim 1 or 2, characterized in that the fuel openings (2) are arranged on a trailing edge of the film applicator (1). Fuel injection nozzle according to one of claims 1 to 5, characterized in that the fuel openings (2) with respect to the alignment of their central axes (5) in the circumferential direction in the same direction to the inner (8) and outer air swirl (9) are arranged. Fuel injection nozzle according to one of claims 1 to 5, characterized in that the fuel openings (2) with respect to the alignment of their central axes (5) in the circumferential direction in the counter-rotation to the inner (8) and outer air swirl (9) are arranged. Fuel injection nozzle according to one of claims 1 to 7, characterized in that the fuel openings (2) are arranged in a single row. Fuel injection nozzle according to one of claims 1 to 7, characterized in that the fuel openings (2) are arranged in multiple rows. Fuel injection nozzle according to one of claims 1 to 8, characterized in that the fuel openings (2) are arranged in alignment with each other. Fuel injection nozzle according to one of claims 1 to 8, characterized in that the fuel openings (2) are arranged staggered to each other. Fuel injection nozzle according to one of claims 1 to 11, characterized in that the film applicator (1) is formed lamellar. Fuel injection nozzle according to claim 12, characterized in that the film applicator (1) has a spiral geometry in the circumferential direction.

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