EP1084368A1

EP1084368A1 - Fuel injector

Info

Publication number: EP1084368A1
Application number: EP99936291A
Authority: EP
Inventors: Carsten Tiemann
Original assignee: Siemens AG
Current assignee: Siemens AG
Priority date: 1998-06-04
Filing date: 1999-05-20
Publication date: 2001-03-21
Anticipated expiration: 2019-05-20
Also published as: JP2002517700A; WO1999063268A1; EP1084368B2; US6676048B1; DE59902355D1; EP1084368B1

Abstract

The invention relates to a fuel injector (1) with an outlet area (5) in which an outlet duct (7) extends along an injector axis (2) and said outlet duct (7) terminates on an edge (9) of the outlet. The fuel injector is characterised in that the edge (9) of the outlet around said injector axis is not rotationally symmetrical.

Description

description

Fuel nozzle

The invention relates to a fuel nozzle with an orifice area in which an orifice channel extends along a nozzle axis. The fuel nozzle is particularly suitable for liquid fuel.

DE 32 35 080 AI describes a return injection nozzle in which two opposite liquid feeds open tangentially into a circular cylindrical swirl space. An injection channel is connected to the swirl chamber on the one hand and a return bore is connected on the other hand. The return injection nozzle is particularly suitable for the atomization of liquid fuel in gas turbine combustion chambers. Atomization is achieved in that fuel flows tangentially into the swirl chamber and is combined to form a main stream, a swirl being given to the main stream by a circular guide in the swirl chamber, which swirl is retained in the injection channel. As a result, the fuel jet fans out in a conical shape when the fuel exits the injection channel. On the other hand, fuel is returned via the return hole. While maintaining a constant fuel flow to the return injector, the amount of fuel injected is controlled by adjusting the amount of fuel returned.

In the article "Active damping of self-excited combustion chamber vibrations (AIC) in pressure atomizer burners by modulating the liquid fuel supply" by J. Hermann, D. Vortmeyer and S. Gleis, VDI reports No. 1090, 1993, describes how a combustion vibration in the combustion chamber of a gas turbine or a boiler and how it can be actively damped. During combustion in the combustion chamber, the self-excited combustion vibration, which is also referred to as combustion instability. Such a combustion oscillation arises from the interaction between a fluctuating heat release during combustion and the acoustics of the combustion chamber. A combustion vibration is often accompanied by high noise emissions and mechanical stress on the combustion chamber, which can lead to the destruction of components.

DE-OS 20 33 118 shows a gas burner for a gas-fired melting furnace. In order to create a high flame temperature, the gas burner has a nozzle converging in the area of the mouth in the form of a gap. This ensures a high heat concentration.

The object of the invention is to provide a fuel nozzle through which a combustion oscillation is at least reduced.

According to the invention, this object is achieved by a fuel nozzle with a mouth area in which a mouth channel extends along a nozzle axis, which mouth channel does not end convergingly at a mouth edge, the mouth edge not being rotationally symmetrical about the nozzle axis.

In the fuel nozzle, fuel is led through the mouth area in the mouth channel. The mouth channel is non-converging in the mouth area, that is, it does not narrow, so that there is no pressure loss. The

Fuel escapes from the mouth channel at the mouth edge into the outside area. The jet expands, ie a divergent, fanned out fuel jet is obtained. Because the mouth rim is not rotationally symmetrical about the nozzle axis, the divergent fuel jet is also not rotationally symmetrical. A distorted fuel cone is thus obtained, which is at least in two spatial directions has a different extent perpendicular to the beam direction. The spatial area in which the combustion takes place is distorted accordingly. This distortion of the combustion area influences the occurrence of a combustion oscillation. The area of combustion is shifted and pulled apart so that the acoustic system of burner and burner environment is detuned. The fuel nozzle and thus the emerging fuel cone are oriented in such a way that there is a reduction in the combustion oscillations up to hm to a complete suppression of the combustion oscillations.

The rim of the mouth is preferably asymmetrical about the nozzle axis. This means that the edge of the mouth has to undergo a complete turn around the nozzle axis in order to come back into alignment with its original position.

The rim of the mouth preferably has a double symmetry. The mouth edge is further preferably an ellipse or a rectangle, in particular with rounded corners. The two-fold symmetry means that the mouth edge is half a turn, i.e. 180 °, must experience in order to come with its original position in the cover.

The edge of the mouth preferably corresponds to a contour which is formed by a rectangle and a circle, the center of the circle being on the center of gravity of the rectangle and projecting beyond the narrow side of the rectangle, and the contour being the outer edge of the rectangle and the circle. encloses it.

The mouth edge preferably corresponds to a contour which is formed by two rectangles which are perpendicular to one another and have a common center of gravity, the contour enclosing the outer edge of both rectangles. The mouth channel preferably has a channel wall, each point of the channel wall having an axial distance from the nozzle axis and an axial position along the nozzle axis, and the axial distance being different for at least two points on the channel wall which have the same axial position. The axis spacing for points on the channel wall of the same axial position preferably changes continuously along a circumferential direction around the nozzle axis. The outlet channel is therefore not rotationally symmetrical about the nozzle axis. This means that the fuel is carried a little way in the mouth area in a non-rotationally symmetrical flow. A non-rotationally symmetrical shape is thus impressed on the fuel flow, which, when the fuel emerges from the fuel nozzle, leads particularly efficiently to the formation of a non-rotationally symmetrical, distorted fuel cone.

The mouth canal preferably widens towards the edge of the mouth.

The rim of the mouth preferably has a notch. Such an indentation deflects fuel more strongly in the direction of the indentation when it emerges from the fuel nozzle than in the other directions of the mouth rim. Such a notch in turn ensures that fuel is not deflected to the same extent in all spatial directions. A distorted fuel cone is also formed.

A fuel nozzle for liquid fuel, in particular petroleum, is preferred. The fuel nozzle is preferably used in a burner for a gas turbine, in particular for a stationary gas turbine.

The invention is illustrated by way of example and partly schematically with reference to the drawing. Show it: FIG. 1 shows the side view of a fuel nozzle,

FIG. 2 shows the top view of the fuel nozzle of FIG. 1,

FIG. 3 shows a plan view of a further fuel nozzle,

FIG. 4 shows a longitudinal section through the mouth area of a fuel nozzle,

FIG. 5 shows a top view of a further fuel nozzle,

Figure 6 is a side view of the fuel nozzle of Figure 5 and

7 shows a burner arrangement in an annular combustion chamber.

The same reference symbols have the same meaning in the different figures.

FIG. 1 shows the side view of a fuel nozzle 1. A cylindrical nozzle body 3 tapers in a frustoconical section to a likewise cylindrical mouth area 5 with an end face 5A. Directed along a nozzle axis 2 in the fuel nozzle 1 is a mouth channel 7, which ends at the end of the mouth region 5 with a mouth edge 9. A right-angled cut is made through the mouth area 5 so that a bevel 10 of the channel wall 8 of the mouth channel 7 is visible. Due to this bevel 10, the mouth rim 9 is not rotationally symmetrical about the nozzle axis 2. This is clear in FIG. 2.

FIG. 2 shows a top view of the fuel nozzle 1 from FIG. The mouth edge 9 thus corresponds to a contour defined by the outer edge of a rectangle 11 and one Circle 13 is formed, the circle 13 with its center 15 is on the center of gravity 17 of the rectangle 11 and protrudes beyond the narrow side of the rectangle 11.

Because the mouth rim 9 is not rotationally symmetrical about the nozzle axis 2, a non-rotationally symmetrical, distorted fuel cone 33 is formed when fuel emerges from the fuel nozzle 1 (see also FIG. 4). This distorted fuel cone 33 means that the combustion area is also distorted. By suitably orienting the fuel nozzle 1, an acoustic interaction between the fuel nozzle 1 and its surroundings can be detuned in such a way that at most slight combustion vibrations are formed. Such suppression of combustion vibrations is possible particularly effectively if a plurality of fuel nozzles 1 are arranged in a combustion chamber. Such fuel nozzles 1 are preferably used in burners for gas turbines. The large-volume, high-energy burns in gas turbines can cause combustion vibrations, which not only cause considerable noise pollution, but also material damage.

The fuel nozzle 1 also has a favorable influence on a nitrogen oxide reduction. Due to the distorted fuel cone, a better fine distribution of fuel can be achieved. In particular, there is a small droplet size for the fuel. The better distribution and the small droplet size of the fuel result in a comparison of the flame temperatures of the combustion. As a result, the maximum temperatures are not so high, which largely determine nitrogen oxide production. Furthermore, there is better mixing with water sprayed at the same time, if necessary. Water is injected to lower flame temperatures in the combustion, which reduces nitrogen oxide formation. With a non-rotationally symmetrical fuel cone 33 (see FIG. 4), there is a better penetration of fuel and water. FIG. 3 shows a top view of a fuel nozzle 1. The difference from the fuel nozzle 1 from FIGS. 1 and 2 is that the mouth rim 9 represents a contour which is formed by a rectangle 21 and a rectangle 23 perpendicular to it. The two rectangles 21, 23 have a common center of gravity 25, 27.

FIG. 4 shows a longitudinal section through the mouth area 5 of a fuel nozzle 1. The fuel channel 7 widens towards the mouth rim 9. Two opposite points P1, P2 on the channel wall 8 have an axial position B along the nozzle axis 2 compared to an arbitrarily selected zero position. The point P1 is at a distance AI from the nozzle axis 2. The point P2 is at a distance A2 from the nozzle axis 2. The distance AI is greater than the distance A2. The respective distance A to the nozzle axis 2 changes continuously along a circumferential direction U around the nozzle axis 2, that is to say for points P on the channel wall 8, which all have the same axial position B along the nozzle axis 2. A non-rotationally symmetrical shape is impressed on a fuel flow in the mouth channel 7. This manifests itself when the fuel emerges from the orifice channel 7 in a non-rotationally symmetrical, distorted fuel cone 33. This has the advantages explained above with regard to the suppression of combustion vibrations and the reduction of nitrogen oxide emissions.

FIG. 5 shows a top view of a fuel nozzle 1. FIG. 6 shows the fuel nozzle 1 of FIG. 5 in a side view. In the end face 5A of the mouth area 5, a semicylindrical notch 31 is cut or said, which cuts the mouth of the mouth channel 7. As a result, the rim of the mouth 9 also has a notch 31. Fuel is sprayed particularly far to the side at this notch 31. This results in a non-rotationally symmetrical fuel cone 33 for that from the fuel nozzle 1 leaking fuel. This in turn results in the advantages already mentioned for reducing combustion vibrations and nitrogen oxide emissions.

FIG. 7 shows a burner arrangement 40 comprising a plurality of burners 42 in an annular combustion chamber 44 of a gas turbine, which is not shown in detail. The annular combustion chamber 44 is rotationally symmetrical about a combustion chamber axis 46. It has an inner wall 48 and an outer wall 50 which enclose an annular space 51. The inside of the outer wall 50 and the outside of the inner wall 48 are provided with a fire-resistant outer lining 52.

The mouth edges 9 of the burner 42 are not rotationally symmetrical and irregularly oriented to one another. This results in a reduced tendency to form a combustion oscillation, since the combustion oscillations emanating from the individual burners 42 overlap irregularly and largely extinguish them in the process.

Claims

1. Fuel nozzle (1) with a mouth region (5) in which a mouth channel (7) extends along a nozzle axis (2), which mouth channel (7) ends at a mouth edge (9) non-converging, characterized in that the mouth edge ( 9) is not rotationally symmetrical about the nozzle axis (2).

2. Fuel nozzle (1) according to claim 1, d a d u r c h g e k e n n z e i c h n e t that the mouth edge (9) is asymmetrical about the nozzle axis (2).

3. Fuel nozzle (1) according to claim 1, d a d u r c h g e k e n n z e i c h n e t that the mouth edge (9) has a double symmetry.

4. Fuel nozzle (1) according to claim 3, d a d u r c h g e k e n n z e i c h n e t that the mouth edge (9) is an ellipse.

5. The fuel nozzle (1) as claimed in claim 3, so that the mouth rim (9) is a rectangle, in particular with rounded corners.

6. Fuel nozzle (1) according to claim 1 or 3, characterized in that the mouth edge (9) corresponds to a contour which is formed by a rectangle (11) and a circle (13), the circle (13) with its The center (15) lies on the center of gravity (17) of the rectangle (11) and protrudes beyond the narrow side of the rectangle (11) and the contour encloses the outer edge of the rectangle (11) and the circle (13).

7. Fuel nozzle (1) according to claim 1 or 3, characterized in that the mouth edge (9) corresponds to a contour which is formed by two mutually perpendicular, a common center of gravity (25, 27) having rectangles (21, 23), wherein the contour encloses the outer edge of both rectangles (21, 23).

8. Fuel nozzle (1) according to one of the preceding claims, characterized in that the mouth channel (7) has a channel wall (8), each point (P) of the channel wall (8) having an axis distance (A) to the nozzle axis (2) and one has axial position (B) along the nozzle axis (2) and the axial distance (A) is different for at least two points (Pl, P2) on the channel wall (8) which have the same axial position (B).

9. Fuel nozzle (1) according to claim 8, characterized in that the axis distance (A) for points (P) on the channel wall (8) of the same axial position (B) along a circumferential direction (U) around the nozzle axis (2) constantly changing.

10. Fuel nozzle (1) according to one of the preceding claims, d a d u r c h g e k e n n e z e i c h n e t that the

Mouth canal (7) widens towards the mouth rim (9).

11. Fuel nozzle (1) according to one of the preceding claims, d a d u r c h g e k e n n z e i c h n e t that the mouth edge (9) has a notch (31).

12. Fuel nozzle (1) according to one of the preceding claims, for liquid fuel, in particular for petroleum.

13. Fuel nozzle (1) according to one of the preceding claims, in a burner (42) for a gas turbine, in particular for a stationary gas turbine.

14. Burner arrangement (40) with a plurality of burners (42) which are arranged in a common combustion chamber (44), at least two of the burners (42) having a fuel nozzle (1) according to one of the preceding claims.

15. Burner arrangement (40) according to claim 14, which is arranged in an annular combustion chamber (44) for a gas turbine.