EP1892472A1 - Combustion system particularly for a gas turbine - Google Patents

Abstract

A burner (1, 101), in particular for a gas turbine, having at least one nozzle tube (7, 107) and a fuel fluid supply line (9) communicating with the nozzle tube (7, 107) for feeding a fuel fluid into the nozzle tube (7 , 107). The nozzle tube (7, 107) has a nozzle outlet opening (15, 115) and is designed for injecting a jet of fuel fluid or of a mixture of air and fuel fluid into a combustion chamber (3). In addition, the nozzle tube (7, 107) in the region of the nozzle outlet opening (15, 115) to the center of the opening projecting elements (19, 119).

Description

The present invention relates to a combustion system, in particular a combustion system for a gas turbine with a combustion chamber and at least one nozzle tube, which opens into the combustion chamber with a nozzle outlet opening.

Recently, so-called jet flames are discussed as an alternative to swirl flames in combustion systems for gas turbine plants. In jet flames, a fuel fluid or a mixture of fuel fluid and air is introduced by means of a nozzle tube as a jet into the combustion chamber. Jet flames enable emissions of nitrogen oxides (NO _x) emissions, which are as low as in premixed flames swirl, while at the same time allow the distribution of heat release over a greater compared to the premixed swirl flame region in the combustor. As a result of the heat release over a larger area, jet flames open up a potential for reducing thermoacoustically induced vibrations. Furthermore, jet flames enable the burning of very different fuel fluids, which ensures a high flexibility of the combustion system. High flexibility is one of the main goals of modern combustion systems.

The stabilization of a jet flame, however, remains an incompletely solved task. So far, jet flames are mainly stabilized by the entrainment of hot reaction gases from an outer recirculation zone of the combustion chamber. The entrainment of the hot reaction gases has been improved by increasing the jet velocity and adjusting the geometry of the combustion assembly. The adjustment of the geometry is usually carried out by establishing a specific ratio between the diameter of the combustion chamber and the diameter of the nozzle opening into the combustion chamber of the nozzle tube. The Flame stability, however, may still be unsatisfactory, in particular with regard to different operating points of gas turbine plants or when using fuels with a high hydrogen content, which lead to a high combustion speed.

In contrast, it is an object of the present invention to provide an advantageous burner for jet flames and an advantageous combustion system for jet flames.

This object is achieved by a burner according to claim 1 or by a combustion system according to claim 12. The dependent claims contain advantageous embodiments of the invention.

A burner according to the invention, which in particular can be designed as a burner for a gas turbine, comprises at least one nozzle tube and a fuel fluid supply line communicating with the nozzle tube for supplying a fuel fluid into the nozzle tube and optionally additionally an air supply line communicating with the nozzle tube for supplying Combustion air in the nozzle tube. The nozzle tube has a nozzle outlet opening and is designed to inject a jet of fuel fluid or of a mixture of air and fuel fluid into a combustion chamber. The nozzle tube has in the region of the nozzle outlet opening to the center of the opening projecting elements. The elements projecting towards the center of the opening thus lead to an increase in the turbulent fluctuations in the region of the boundary surface between the jet and the recirculated combustion exhaust gases in the well-worn jet, which in turn intensifies the entrainment of the combustion exhaust gases. As a consequence, the stability of the flame is increased.

In a first implementation of the invention, the protruding elements are provided by a nozzle tube section having a corrugated inner circumferential surface extending up to the nozzle outlet opening educated. This realization leads to an enlargement of the surface of the jet emerging from the nozzle opening. In this implementation, since the number of turbulent fluctuations depends on the size of the interface between the jet and the hot reaction gases, ie the combustion gases, in the recirculation zone, the enhancement of vortex formation is essentially due to the increased radiation surface.

gegeben ist.The corrugated inner peripheral surface at the nozzle outlet opening may in particular be designed such that it has a maximum deflection A about a mean opening radius R of the nozzle outlet opening and the ratio of the deflection to the mean opening radius through the relationship $$0.03<{{}^A/}_R<0.2$$

given is.

The corrugated inner peripheral surface may in particular have the shape of a sine wave extending over the circumference of the nozzle outlet opening. But other in the broadest sense corrugated forms, such as sawtooth shapes, are possible.

gegeben. Im durch die Formel gegebenen Verhältnis der Länge des Übergangsbereiches zur maximalen Amplitude lassen sich besonders vorteilhafte Resultate für die Flammenstabilität erzielen.In a development of the burner with the corrugated inner circumferential surface, the nozzle tube has a nozzle tube section remote from the nozzle opening and a transition section. The transition section represents a transition from the nozzle tube section with a circular opening cross-section to the nozzle tube section with the corrugated inner circumferential surface. The maximum amplitude of the corrugated inner circumferential surface is reached directly at the nozzle outlet opening. The ratio of the length L _{T of} the transition region to the maximum amplitude A is given by the formula $$1<{{}^{L_T}/}_{2A}<5$$

given. In the given by the formula ratio of the length of the transition region to the maximum amplitude can be achieved particularly advantageous results for flame stability.

In an alternative embodiment of the burner, the protruding elements are formed by vanes arranged in the region of the nozzle outlet opening on the inner circumferential surface of the nozzle tube, which wings may in particular be delta wings. Delta wings are triangular in shape and have a relatively low profile thickness relative to their length and depth. The wings, in particular the delta wings lead to an increased vortex formation in the area of the wing edges. In contrast to the first implementation, the increased vortex formation is not first induced by the enlarged radiation surface, but is already present at the exit of the jet from the nozzle outlet opening.

gegeben. Die Verhältnisse, welche der angegebenen Beziehung genügen, führen zu besonders guten Ergebnissen beim Stabilisieren der Strahlflamme.The blades protrude at the nozzle exit port via the distance S from the inner circumferential surface, which is formed at the nozzle orifice in a circular shape with an opening diameter D, into the nozzle orifice. The ratio of the distance S to the opening diameter D is determined by the relationship $$0.03<{{}^S/}_D<0.2$$

given. The conditions which satisfy the given relationship lead to particularly good results in stabilizing the jet flame.

In a particular embodiment of the implementation with wings in the region of the nozzle outlet opening the wings are inclined at an angle α with respect to the radial direction of the nozzle outlet opening. The angle α can in this case be in the range 65 ° <α <85 °, in particular. The inclined wings, in particular those with angles of inclination in the specified range, lead to a particularly advantageous vortex formation in the surface region the exiting from the nozzle outlet opening fluid jet. This leads in particular to good results for the flame stability, if the ratio of the distance S to the opening diameter D of the nozzle outlet opening satisfies the relationship given above.

gegeben ist. Das Vorstehen des Düsenrohres in die Brennkammer erhöht den Effekt, den das Mitreißen von heißen Verbrennungsabgasen der Rezirkulationszone auf den Strahl ausübt, weil die Düsenaustrittsöffnung nähr an die Rezirkulationszone herangeführt oder gar in diese hineingeführt ist.According to the invention, a combustion system with a combustion chamber and a burner is also provided. The burner comprises at least one nozzle tube and a fuel fluid supply line communicating with the nozzle tube for supplying a fuel fluid into the nozzle tube and optionally additionally an air supply line communicating with the nozzle tube for supplying combustion air into the nozzle tube. The nozzle tube has a nozzle outlet opening into the combustion chamber and is designed to inject a jet of fuel fluid or a mixture of air and fuel fluid into the combustion chamber. In the combustion system according to the invention, the nozzle tube projects into the combustion chamber. In particular, the nozzle tube may have an opening diameter D and project over a length L in the combustion chamber, wherein the ratio of the length L to the opening diameter D by the relationship $$0.3<{{}^S/}_D<3$$

given is. The projection of the nozzle tube into the combustion chamber increases the effect that the entrainment of hot combustion exhaust gases of the recirculation zone exerts on the jet, because the nozzle exit orifice near the recirculation zone is introduced or even into this.

The nozzle tube projecting into the combustion chamber can be equipped, in particular in the region of the nozzle outlet opening, with elements projecting towards the center of the opening, as have been described with reference to the burner according to the invention. In other words, the burner may in particular be a burner according to the invention.

Fig. 1

zeigt ein erfindungsgemäßes Verbrennungssystem mit einem Brenner und einer Brennkammer in einer schematisierten, geschnittenen Seitenansicht.

Fig. 2

zeigt eine Draufsicht auf die Düsenaustrittsöffnung des Brenners aus Fig. 1.

Fig. 3

zeigt eine alternative Ausgestaltung des Brenners im Verbrennungssystem aus Fig. 1 in einer geschnittenen, schematisierten Seitenansicht.

Fig. 4

zeigt eine Draufsicht auf die Düsenausrittsöffnung der alternativen Ausgestaltung des Brenners.

Fig. 5

zeigt ein zweites Ausführungsbeispiel für ein erfindungsgemäßes Verbrennungssystem mit einem Brenner und einer Brennkammer in einer schematisierten, geschnittenen Seitenansicht.

Further features, properties and advantages of the present invention will become apparent from the following description of embodiments with reference to the accompanying figures.

Fig. 1

shows a combustion system according to the invention with a burner and a combustion chamber in a schematic, sectional side view.

Fig. 2

shows a plan view of the nozzle outlet opening of the burner of FIG. 1st

Fig. 3

shows an alternative embodiment of the burner in the combustion system of Fig. 1 in a sectioned, schematic side view.

Fig. 4

shows a plan view of the nozzle exit opening of the alternative embodiment of the burner.

Fig. 5

shows a second embodiment of a combustion system according to the invention with a burner and a combustion chamber in a schematic, sectional side view.

An embodiment of a combustion system according to the invention is shown in a highly schematic representation in Fig. 1. The figure shows a section through the longitudinal axis of the combustion system and shows a burner 1 and a combustion chamber. 3

The burner is designed to generate a jet flame 5. It comprises a nozzle tube 7, which in the present embodiment is in communication with a fuel supply line 9 and an air supply line 11. The fuel fluid supplied via the fuel supply line 9, for example, gas (such as natural gas) or oil (such as fuel oil) is mixed in a mixer 13 and supplied to the nozzle tube 7.

Via a nozzle outlet opening 15, the premixed air / fuel mixture is injected into the combustion chamber 3 to form the jet flame 5. Usually, the diameter of the nozzle outlet opening with the dimension of the combustion chamber opening W in the ratio 1 <W / D <4.

In the outer region of the combustion chamber 3 is formed at the present jet flame 5, a recirculation zone 6, in which hot combustion gases flow back in the radially outer region of the combustion chamber 3 in the direction of the burner 7 and in the upstream region of the combustion chamber 3 in its direction of movement in the direction of the deflected radially inner region of the combustion chamber. Between the recirculated exhaust gas 17 and the peripheral surface of the air / fuel mixture in the jet flame 5, shear forces occur, which entrain the recirculated exhaust gas 17 in the flow direction F of the air / fuel mixture. Due to this entrainment effect, the jet flame 5 is stabilized in the combustion chamber 3. For the entrainment effect, primarily turbulent fluctuations in the peripheral surface of the jet flame 5 are responsible.

The nozzle tube 7 of the burner 1 has a corrugated tube wall 19 in the region of the nozzle outlet opening 15. In the present exemplary embodiment, the corrugation is realized in that the tube wall 19 has the shape of a standing sine wave oscillating about an average tube radius R with an amplitude A. However, the corrugation can also be implemented in its inner wall by incorporating a sinusoidal contour in the circumferential direction of the nozzle tube. The curl does not necessarily have sinusoidal form. Other shapes, such as sawtooth shapes, are possible.

gegeben.The amplitude A of the corrugation has its maximum value at the nozzle outlet opening 15. It decreases towards upstream pipe sections until finally reaching a pipe section 21 in which the pipe has a circular cross-section. The transition area, in the amplitude decreases from its maximum value A to zero, in the axial direction of the nozzle tube 7 has a length L _T. The ratio of the length L _{T of} the transition region to the maximum amplitude A is defined by the relationship $$1<{{}^{L_T}/}_{2A}<5$$

given.

gegeben ist. Es sei an dieser Stelle angemerkt, dass Fig. 2 lediglich beispielhaft und schematisch für die Form der Wellung steht. Insbesondere kann die Zahl der Wellenberge und Wellentäler auch kleiner oder größer sein, als dies in Fig. 2 dargestellt ist.Due to the corrugation of the nozzle tube 7 in the region of the nozzle outlet opening 15, the surface of the jet emerging from the nozzle outlet opening 15 of air / fuel mixture is increased in comparison to a jet of air / fuel mixture emerging from a nozzle outlet opening with a round cross section and the radius R. The enlargement of the surface of the jet leads to more turbulent fluctuations and thus to an amplification of the described entrainment effect. Particularly advantageously, the entrainment effect can be enhanced if the ratio of the deflection A of the corrugation to the mean radius R of the nozzle outlet opening is enhanced by the relationship $$0.03<{{}^A/}_R<0.2$$

given is. It should be noted at this point that Fig. 2 is merely exemplary and schematic of the shape of the corrugation. In particular, the number of wave crests and troughs may also be smaller or larger than shown in FIG.

gegeben. Außerdem sind die Deltaflügel 119 im vorliegenden Ausführungsbeispiel um einen Winkel α im Bereich zwischen 65° und 85° gegen die Radialrichtung im Düsenrohr 107 geneigt. Es sind aber auch Ausführungsformen ohne Neigung möglich.Fig. 3 shows a second embodiment of the nozzle tube of the burner according to the invention. The figure shows the nozzle tube 107 according to the second variant in a schematic section along its central longitudinal axis. In contrast to the nozzle tube 7 of the first embodiment, the nozzle tube 107 of the second embodiment in the region of the nozzle outlet opening 115 no corrugation. Instead are arranged in the region of the inner peripheral surface of the nozzle outlet opening 115 delta wing 119. The delta wings 119 protrude beyond the distance S into the nozzle outlet opening 115. The ratio of the distance S to the diameter D of the nozzle outlet opening 115 is in this case in particular by the relationship $$0.03<{{}^S/}_D<0.2$$

given. In addition, the delta wings 119 are inclined in the present embodiment by an angle α in the range between 65 ° and 85 ° against the radial direction in the nozzle tube 107. But there are also embodiments without inclination possible.

At the edges of the delta wings 119 arranged in the region of the nozzle outlet opening 115, vortex formation takes place, which continues in the surface of the jet emerging from the nozzle outlet opening 115. The vortices increase the turbulent fluctuations in the boundary between the jet and the recirculated exhaust gas, thus increasing the entrainment effect.

A further exemplary embodiment of the combustion system according to the invention is shown in FIG. The figure shows the combustion system in a section along its longitudinal axis and shows a burner 201 and a combustion chamber 203.

The burner comprises a nozzle tube 207, a fuel supply line 209 and an air supply line 211 and a mixer 213, which is connected upstream of the nozzle tube 207 and into which the fuel supply line 209 and the air supply line 211 open. In contrast to the burner in the first exemplary embodiment of the combustion system according to the invention, the nozzle tube 207 has neither a corrugation nor delta wings in the region of its nozzle outlet opening 215. It should be mentioned at this point, however, that the burner also in the second embodiment of the combustion system can be equipped with a corrugation or with delta wings in the region of its nozzle outlet opening 215.

gegeben ist. Aufgrund des Hineinragens in die Brennkammer 203 kann die Düsenaustrittsöffnung 215 näher an die Rezirkulationszone in der Brennkammer herangeführt werden, sodass bereits kurz nach dem Austritt des Strahls 205 aus der Düsenaustrittsöffnung 215 der Mitreißeffekt eintritt. Der Mitreißeffekt kann daher die Strahlflamme 205 weitestgehend über ihre gesamte Länge stabilisieren.In contrast to the combustion system illustrated in FIG. 1, in the combustion system illustrated in FIG. 5, the nozzle tube 207 projects into the combustion chamber 203 by the distance L. The distance L, by which the nozzle tube 207 protrudes into the combustion chamber 203, is with the opening diameter D of the nozzle outlet opening preferably in a relationship by $$0.3<{{}^L/}_D<3$$

given is. Due to the entry into the combustion chamber 203, the nozzle exit opening 215 can be brought closer to the recirculation zone in the combustion chamber, so that shortly after the exit of the jet 205 from the nozzle exit opening 215 the entrainment effect occurs. The entrainment effect can therefore stabilize the jet flame 205 largely over its entire length.

By means of the invention, the entrainment effect for the hot gases in the outer recirculation zone is increased. In addition, the increased turbulent fluctuations ensure uniform combustion with low acoustic amplitudes, thus suppressing the occurrence of combustion oscillations. An optimization of the stability of the jet flame can be brought about by combining the burner illustrated in FIGS. 1 to 4 with the combustion system illustrated in FIG. 5.

Claims (13)

Burner (1, 101), in particular for a gas turbine, having at least one nozzle tube (7, 107) and a fuel fluid supply line (9) communicating with the nozzle tube (7, 107) for supplying a fuel fluid into the nozzle tube (7, 107) wherein the nozzle tube (7, 107) has a nozzle outlet opening (15, 115) and is designed for injecting a jet (5) of fuel fluid or of a mixture of air and fuel fluid into a combustion chamber (3), characterized in that the nozzle tube (7, 107) in the region of the nozzle outlet opening (15, 115) to the center of the opening projecting elements (19, 119). Burner (1) according to claim 1, characterized in that the projecting elements are formed by a nozzle tube opening (15) reaching nozzle tube section with corrugated inner peripheral surface (19). Burner (1) according to claim 2, characterized in that the corrugated inner circumferential surface (19) at the nozzle outlet opening (15) has a maximum deflection A about a mean Öffnungsradis R of the nozzle outlet opening (15) and the ratio of the deflection to the average opening radius through the relationship $$0.03<{{}^A/}_R<0.2$$

given is. Burner (1) according to claim 2 or 3, characterized in that the corrugated inner peripheral surface (19) has the shape of a sine wave. Burner (1) according to claim 2 or 3, characterized in that the corrugated inner peripheral surface (19) has a sawtooth shape. Burner (1) according to one of claims 2 to 5, characterized in that the nozzle tube (7) from the nozzle opening (15) remote nozzle tube section (21) having a circular opening cross-section and a transition section of the nozzle tube section (21) having the circular opening cross-section to the nozzle tube portion having the corrugated inner peripheral surface (19), wherein the maximum amplitude A of the corrugated inner peripheral surface (19) at the nozzle exit port (15) is achieved and the ratio of the length L _{T of} the transition region to the maximum amplitude A by the relationship $$1<{{}^{L_T}/}_{2A}<5$$

given is. Burner (101) according to claim 1, characterized in that the projecting elements are formed by vanes (119) arranged in the region of the nozzle outlet opening (115) on the inner circumferential surface (107) of the nozzle tube. Burner (101) according to claim 7, characterized in that the wings are designed as delta wings (119). Burner (101) according to claim 7 or 8, characterized in that the wings (119) protrude at the nozzle outlet opening (115) over the distance S from the inner peripheral surface into the nozzle opening, the inner peripheral surface at the nozzle opening has a circular circumference with opening diameter D. and the ratio of the distance S to the opening diameter D through the relationship $$0.03<{{}^S/}_D<0.2$$

given is. Burner assembly (101) according to any one of claims 7 to 9, characterized in that the wings (119) are inclined by an inclination angle α with respect to the radial direction of the nozzle outlet opening (115). Burner (101) according to claim 10, characterized in that the inclination angle α in the range 65 ° <α <85 °. Combustion system, in particular for a gas turbine, with a combustion chamber (203) and a burner (201), in particular with a burner according to one of the preceding claims, which has at least one nozzle tube (207) and a fuel fluid supply line (207) communicating with the nozzle tube (207) ( 209) for supplying a fuel fluid into the nozzle tube (207), wherein the nozzle tube (207) has a nozzle outlet opening (215) opening into the combustion chamber (203) and for injecting a jet (205) of fuel fluid or a mixture of air and fuel fluid into the combustion chamber (203), characterized in that the nozzle tube (207) protrudes into the combustion chamber. A combustion system according to claim 12, characterized in that the nozzle tube (207) has an opening diameter D and projects over a length L in the combustion chamber (203), wherein the ratio of the opening diameter D to the length L by the relationship $$0.3<{{}^L/}_D<3$$

given is.

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