Supply device, burner system, and method

Abstract

The invention relates to a supply device (1), in particular for use in a gas turbine, for supplying an oxidizing agent (38) and fuel (27) to a combustion chamber (3) without a swirling flow, comprising a supply nozzle (10) with a nozzle channel (14), in particular a cylindrical nozzle channel, which is delimited by a nozzle wall (16) and is oriented along a longitudinal axis (L) and which leads to a fuel chamber-side outlet opening (12) so as to adjoin the combustion chamber (3), and an injector element (24) for adding the fuel (27) into the nozzle channel (14) at an injection point (26). A stable operation using the supply device is achieved in that the injector element (24) is designed to supply liquid fuel (27), and a prefilming device (18), in particular a cylindrical prefilming device, which surrounds the injector element (24) is arranged radially between the injector element (24) and the nozzle wall (16), wherein an outer channel (30) is formed between the nozzle wall (16) and the radial exterior of the prefilming device (18), and an inner channel (34) is formed radially within the prefilming device (18), in particular between the radial interior of the prefilming device (18) and the injector element (24).

Description

[0001]

[0002] Feed device, burner system and process

[0003] The invention relates to a supply device, particularly for use in a gas turbine, for the swirl-free supply of oxidizer and fuel into a combustion chamber. The supply nozzle comprises a supply nozzle with a nozzle channel, which is defined by a nozzle wall and oriented along a longitudinal axis L, and which opens into an outlet opening on the combustion chamber side adjacent to the combustion chamber. The supply nozzle also relates to a burner system with a supply device and a method for the swirl-free supply of oxidizer and fuel into a combustion chamber.

[0004] Such burner systems with at least one such supply device are also known as recirculation-stabilized jet flame burners for non-swirling high-velocity combustion, or FLOX® burner systems. One such burner system is disclosed, for example, in EP 1 918 641 A2. The combustion zone in the combustion chamber is stabilized during operation by a large-scale, internal combustion-chamber recirculation of exhaust gas, which develops due to the introduction of oxidizer-fuel jets with a sufficiently high axial momentum into the combustion chamber. The recirculation brings the combusted, hot exhaust gas back to the jet root near the supply nozzles and mixes it with the incoming fresh gases. In a known annular arrangement of the supply nozzles, the recirculation zone is generally formed essentially radially within the nozzle ring.

[0005] EP 0 769 655 A2 discloses an airblast atomizing nozzle for operating a burner fired with liquid fuels. The nozzle has a liquid fuel pipe in an air supply line, around which a partition is arranged. The partition forms two concentrically arranged air ducts: an inner air duct and an outer air duct. The air flow flowing through the air ducts is atomizing air. Main combustion air is added further downstream in the duct.

[0006] US 4 261 517 A discloses a fuel nozzle for introducing atomized fuel.

[0007] EP 0 660 038 A2 shows a fuel supply device for introducing a liquid fuel, wherein the combustion air is wired by means of swirl generators.

[0008] US 8 590 812 B2 shows a fuel supply nozzle for supplying liquid and gaseous fuels into a combustion chamber.

[0009] When using liquid fuels in such burner systems, the fuel can interact with the inner nozzle wall, resulting in enriched fuel adhering to the inner nozzle wall reaching the combustion chamber as a ligament or in the form of poorly atomized, large droplets. This has a direct negative impact on the stability, operating range, and emissions of the burner system. The invention is based on the object of providing a supply device of the type mentioned above for the stable operation of a burner system mentioned above, as well as a corresponding burner system and method for supplying the fuel.

[0010] The problem is solved for the supply device with the features of claim 1, for the burner system with the features of claim 20 and for the method with the features of claim 21.

[0011] According to the invention, the supply device is provided with the injector element being designed for adding liquid fuel and with a film-laying device, in particular a cylindrical one, surrounding the injector element (completely radially) being arranged radially between the injector element and the nozzle wall, wherein an outer channel (for the flow through of an external stream) is formed between the nozzle wall and the radial outer side of the film-laying device.

[0012] The film-laying device is designed in particular in the form of a sleeve and / or in particular with open axial ends for the flow of oxidizer.

[0013] The cross-section of the nozzle wall, for example, is constant along its length. The outer channel and / or the inner channel, in particular, have an annular gap with a substantially constant gap height in a respective cross-section (at a constant axial position and / or at least largely along its axial length).

[0014] "Swirl-free" refers to the supply of fuel and oxidizer into the combustion chamber. When the fuel is added into the oxidizer flow within the supply nozzle, a swirl flow may be present.

[0015] The fuel can be, for example, a mixture of liquid hydrocarbons, e.g., kerosene and / or (heating) oil, and / or a liquid hydrocarbon in pure form. The supply device and / or the burner system can also be combined for operation with fuels in other aggregate states, e.g., with gaseous or supercritical fuels, preferably in combination with a (separate) injector element and / or supply device designed for this purpose.

[0016] The film-layer device enables advantageous atomization of the fuel by utilizing the high momentum of the oxidizer flow within the feed nozzle. The combination of film-layer device and injector element makes it possible to utilize the high flow momentum of the process air (the oxidizer flow) available in a FLOX® burner system in the feed nozzle for atomization by means of the film-layer device (particularly at the atomization edge). At the same time, unwanted fluid interaction on the inner wall of the feed nozzle, which is detrimental to the burner system, is avoided. The feed device is particularly suitable for very short installation lengths and feed nozzles and is also suitable for direct injection into the combustion chamber (atomization edge at the outlet opening).

[0017] Preferably, an inner channel (for the flow of an inner stream) is formed radially within the film-laying device, in particular between the radial inner side of the film-laying device and the injector element. This configuration allows the entire oxidizer stream flowing through the feed nozzle to be divided into an outer stream and an inner stream, thereby advantageously providing degrees of design freedom for improved atomization and fuel placement.

[0018] In particular, for advantageous flow guidance, with the lowest possible pressure loss and / or while avoiding secondary flow (e.g., turbulence), the film-laying device preferably has, at least over a large part of its axial length (more than 50%, preferably over the entire axial length), at least substantially (e.g., apart from a functionally favorable shape at the edges), constant external dimensions, in particular a constant internal diameter and / or external diameter. In particular, the entire film-laying device runs parallel to the nozzle wall.

[0019] For effective atomization, the film-laying device has an atomizing edge at its downstream axial end. In particular, the wall of the film-laying device tapers toward the atomizing edge to achieve a sharp-edged atomizing edge. The atomizing edge is preferably oriented axially, without a radial component, and without forming a constriction, in order to avoid additional pressure losses or disruptions in the flow pattern. For a streamlined shape, the wall of the film-laying device also tapers toward an upstream edge.

[0020] The injector element is preferably elongated (i.e., with a greater axial than radial extension) and / or projects into the feed nozzle. The injector element has, in particular, at least within the feed nozzle and / or the film-laying device, an at least substantially cylindrical and / or (e.g., apart from the downstream region, at the injection point) constant cross-section.

[0021] Preferably, the feed nozzle, the film-laying device, and the injector element are arranged coaxially with each other with respect to the longitudinal axis. The injector element is, in particular, arranged centrally on the longitudinal axis. This allows for symmetrical flow guidance during operation, accompanied by advantageous combustion properties (stability, low emissions).

[0022] Preferably, the fuel injection point on the injector device is located at the downstream end of the injector device and / or centrally on the longitudinal axis (of the feed device or the feed nozzle). At the injection point, the fuel enters the feed nozzle (within the film-laying device) from the injector element, in particular via a single, central outlet opening or via multiple outlet openings on the injector element. Undesired wetting of the injector device is thus advantageously avoided. The oxidizer flows (inner flow and outer flow) as well as the axial directional component of the fuel (droplet) flow preferably point in the same axial direction, toward the combustion chamber. There is no countercurrent introduction of the fuel into the oxidizer flow.

[0023] In a preferred embodiment, the injection point of the injector device is arranged axially between the atomizing edge and an upstream edge of the film-laying device. The upstream edge and the atomizing edge define the length of the film-laying device, which is, for example, between one and five times the diameter of the film-laying device. Between the upstream edge and the injection point, the inner channel is formed, in particular, in the form of an annular channel.

[0024] Advantageous wetting of the inside of the film-forming device for film formation can be achieved if the injector element is designed to add a fuel cone with an opening angle α (in the axial-radial direction) between 40° and 120°, in particular between 60° and 100°. The fuel is preferably introduced into the feed nozzle with a swirl, whereby the fuel cone forms starting from the injection point. The distance between the injection point and the atomization edge is preferably designed such that (at least) a portion of the fuel impinges on the inside of the film-forming device to form a fuel film (another portion of the fuel, preferably atomized at the injection point, follows the internal flow directly into the feed nozzle, for example). For a compact design, the shortest possible axial extension of the fuel film is desired.The distance between the injection point and the atomization edge is therefore designed, in particular, taking into account the opening angle α of the fuel cone for film formation. For a particularly compact design and uniform fuel distribution over the circumference on the film-laying device (uniform film formation), the injector element is preferably designed as a pressure-swirl injector, with a swirl generator arranged in the injector element to impart swirl during fuel injection. The relative fuel pressure (pressure difference between the injector element and the combustion chamber) when introduced into the injector element is, for example, between 1 bar and 100 bar. The swirl generator has, in particular, a swirl chamber into which fuel is introduced through several, e.g., three, openings arranged symmetrically to one another and tangential to the swirl chamber wall.This imparts an axial and a tangential velocity component to the fuel flow in the swirl chamber. The fuel flow maintains this velocity component as it flows through the outlet opening of the injector element. The injection point is located at the outlet opening of the injector element. The swirl flow creates the radial directional component of the fuel flow downstream of the injection point, for the conical introduction of the fuel into the feed nozzle within the film-forming device.

[0025] Preferably, the (particularly circular) flow cross-section initially tapers conically toward the outlet opening to a narrowest cross-section, and then continuously widens downstream of the narrowest cross-section, particularly in a trumpet-like fashion, to a larger cross-section (e.g., with 1.2 to 3 times the diameter) at the transition to the feed nozzle (exit edge). Due to the particularly trumpet-like widening, the defined opening angle of the fuel cone can be maintained even at comparatively low mass flows due to the Coanda effect.

[0026] In a preferred embodiment, a sharp, continuous exit edge is formed at the outlet opening of the injector element at the transition to the feed nozzle. In particular, the angle between the wall surfaces converging at the exit edge is less than 90°. This allows for (initial) atomization of the fuel for uniform film formation, as well as defined, complete fuel introduction without wetting the exterior of the injector device.

[0027] Preferably, the distance between the injection point and the film-layer atomization edge is designed such that at least a portion of the fuel impinges on the inside of the film-layer device during operation, forming an (atomizable) fuel film. The distance between the injection point and the atomization edge depends in particular on the formation of the fuel film. The length of the fuel film should, for example, be at least 1-2 mm. At the sharp atomization edge, the high momentum of the oxidizer flow is utilized by the shear layer to atomize the fuel film into fine droplets, which are carried further downstream with the oxidizer flow toward the outlet opening.

[0028] The outer channel and the inner channel are preferably designed to match one another in such a way that, during operation, an entire oxidizer stream flowing through the nozzle channel is divided into an outer stream and an inner stream, the velocity of the outer stream being greater than the velocity of the inner stream, e.g. by a factor of between 1.3 and 7, preferably between 2 and 5. The outer stream and the inner stream preferably flow in cocurrent with one another. The outer stream serves for atomization at the downstream end of the film-laying device and protects the nozzle wall from fuel wetting. Atomization into fuel droplets at the atomization edge occurs in particular as a result of high shear velocities of the outer stream. The inner stream interacts with the fuel downstream of the injection point. Downstream of the atomization edge, the fuel droplets follow the oxidizer stream.

[0029] To determine a favorable velocity ratio (or a range of favorable velocity ratios, e.g., depending on the operating point), three design factors in particular are taken into account: first, shear between the outer flow and the inner flow should be achieved for advantageous atomization at the atomization edge; second, wetting of the nozzle wall with fuel downstream of the atomization edge due to a high external momentum from the outer flow should be avoided; and third, a sufficiently high velocity of the inner flow should be provided to propel the fuel film within the film-forming device to the atomization edge. The design is carried out in particular using computational fluid dynamics (CFD) and / or experimentally, whereby, for example, the ratio of the flow cross-sections of the outer channel and the inner channel can be varied.

[0030] Advantageously, the maximum flow impulse for atomization at the atomization edge can be used if the feed nozzle has no reduction in the flow cross-section at and / or downstream of the film-laying device, in particular at and / or downstream of the atomization edge.

[0031] An advantageous fastening of the film-laying device and / or the injector element can be achieved if the film-laying device is fastened to the nozzle wall by means of several, in particular three, fastening elements, which center the injector element, in particular on the radial inner side of the film-laying device. The fastening elements are preferably designed to be aerodynamically favorable, e.g., wing-like, and / or arranged symmetrically to one another about the longitudinal axis and / or at the same axial position. To minimize the influence of the flow at and / or downstream of the injection point(s), the fastening elements are preferably arranged upstream of the injection point (as far as possible, but while maintaining mechanical stability).Another type of fastening is also conceivable, provided that it influences the flow as little as possible and / or ensures an axially symmetrical alignment of the film-laying device and the longitudinal axis of the injector element.

[0032] Preferably, the supply nozzle for adding oxidizer and liquid fuel to the combustion chamber is designed with a high axial momentum, with an average flow velocity at the outlet opening between 40 m / s and 160 m / s, in particular between 80 m / s and 140 m / s. The main flow direction is, in particular, at least largely, or exclusively, axial. In this way, a large-scale recirculation flow within the combustion chamber is induced during operation to stabilize combustion. The design relates, for example, to one or more design points.

[0033] A compact design of a burner system can be achieved if the supply device is designed for operation at a thermal output of 1 kW to 50 kW, for example between 10 kW and 20 kW (with regard to atmospheric pressure and / or air ratios between 0.8 and 2.1, for example). By means of higher pressure, the thermal output can be scaled accordingly for a comparable size. The injector element is designed in particular for operation with a corresponding or low fuel mass flow (e.g. 0.1 to 1 g / s, in particular 0.2 to 0.8 g / s). The diameter of the nozzle channel can be, for example, between 7 mm and 13 mm. The outer diameter of the injector element can be, for example, between 20% and 70% of the diameter of the nozzle channel. The outer diameter of the film-laying device can, for example,between 50% and 85% of the diameter of the nozzle channel, whereby the inner diameter to form the inner channel is larger than the outer diameter of the injector element.

[0034] The design features specified above (individually or in combination) result in extremely advantageous applicability with a comparatively short flame length, even with a compact design of the supply device, which enables the use of a comparatively short combustion chamber. For the required high outputs, several supply devices are preferably used in a burner system, for example in a matrix and / or ring arrangement. This means that the supply device can also be advantageously used in applications with high power requirements where the compact design of a burner system is of paramount importance, for example in aviation. A particularly compact design of the supply device can be achieved if the atomization edge, for direct injection, is arranged close to (e.g., a distance corresponding to a nozzle diameter or less) or at the axial height of the outlet opening.

[0035] The invention will be explained in more detail below using exemplary embodiments with reference to the drawings. They show:

[0036] Fig. 1 shows a burner system according to the invention with several supply devices and a combustion chamber in a simplified schematic representation,

[0037] Fig. 2 A,B a supply device according to the invention for the non-swirling addition of liquid fuel into a burner system in a longitudinal section (Fig. 2A) and in a cross section AA (Fig. 2B), and

[0038] Fig. 3 A,B,C an exemplary injector element for use in the supply device according to Fig. 2 A, B in perspective view from the side (Fig. 3A) and in longitudinal section (Fig. 3B, C).

[0039] Fig. 1 shows an exemplary installation situation of supply devices 1 according to the invention (not shown in detail) in a burner system 4, which is particularly suitable for use in gas turbines in aviation or in applications for energy generation. The burner system 4 has a combustion chamber 3 and an end plate 6 arranged on the upstream side of the combustion chamber 3, via which end plate the supply devices 1 open into the combustion chamber 3. In particular, a plurality of supply devices 1 can be present, which are arranged, for example, in a matrix-like and / or ring-like manner on the end plate 6. The supply devices 1 serve to introduce liquid fuel 27 and oxidizer 38 from a distributor side 2 (not shown in detail here) into the combustion chamber 3 via the end plate 6. The combustion chamber 3 extends axially along a central longitudinal axis M of the burner system 4 and, for example, radially rotationally symmetrically around the same.The feed devices 1 extend along longitudinal axes L which are aligned parallel to the central longitudinal axis M of the burner system 4.

[0040] The fuel 27 can be, for example, a mixture of liquid hydrocarbons, e.g., kerosene and / or (heating) oil, and / or a liquid hydrocarbon in pure form. The burner system 4 is designed in particular for operation with air / fuel ratios between 0.8 and 2.1.

[0041] The burner system 4 is designed as a recirculation-stabilized jet flame burner for unswirled, high-velocity combustion. In this type of burner system, unburned fuel 27 and oxidizer 38 are introduced into the combustion chamber 3 during operation without swirl and with such a high axial momentum that a large-scale recirculation zone 5 is formed in the combustion chamber 3 to stabilize a combustion zone. The average flow velocity at the outlet opening(s) 12 is, for example, between 40 m / s and 160 m / s.

[0042] Fig. 2A and Fig. 2B each show the internal structure of the supply device 1 in a sectional view (Fig. 2A: longitudinal section, Fig. 2B: cross section AA). As Fig. 2A shows, the supply device 1 has a supply nozzle 10 with a nozzle channel 14, which is surrounded by a nozzle wall 16 and aligned along the longitudinal axis L, and which, for example, has a constant cross-section. The nozzle channel 14 opens into a circular outlet opening 12 on the combustion chamber side, which, in the assembled state, borders the combustion chamber 3.

[0043] For adding the fuel 27 into the nozzle channel 14, the supply device 1 comprises an injector element 24. The injector element 24 is arranged in the nozzle channel 14 coaxially to the supply nozzle 10 on the longitudinal axis L. An injection point 26, at which the fuel 27 enters the nozzle channel 14 during operation, is arranged centrally on the longitudinal axis L at the downstream end of the injector element 24 for the most symmetrical introduction of fuel 27 possible.

[0044] The injector element 24 is designed, for example, as a pressure-swirl injector, wherein the liquid fuel 27 is introduced into the injector element 24 at a high relative fuel pressure, e.g., up to 100 bar, and is wired by means of a swirl generator 46 located within the injector element 24 before being introduced into the nozzle channel 14. Other designs of the injector element 24 for introducing liquid fuel 27 are possible, provided, in particular, that advantageous, uniform film formation can be achieved on the film-laying device 18, for example, using a "jet-in crossflow" configuration.

[0045] Fig. 3A, Fig. 3B and Fig. 3C show the injector element 24 in an exemplary embodiment in a perspective view from the side (Fig. 3A) and in longitudinal section (Fig. 3B and Fig. 3C), wherein in Fig. 3C an outlet opening 48 is shown in a detail C.

[0046] As shown in Fig. 3A, the injector element 24 has a substantially cylindrical outer circumference.

[0047] As shown in Fig. 3B, the swirl generator 46 is arranged within the injector element 24, comprising a cylindrical swirl chamber 47 and, in this example, three inlet openings 45 arranged symmetrically to one another to the swirl chamber 47. Downstream of the swirl generator 46, the injector element 24 has the outlet opening 48 with a circumferentially sharp outlet edge 52 adjacent to the supply nozzle 10.

[0048] The swirl generator 46 is held in place by a securing element 44. A compression spring 42 is arranged upstream of the securing element 44 to decouple the swirl generator 46 from vibrations. As shown in more detail in Fig. 3C, downstream of the swirl generator 46, the particularly circular flow cross-section initially tapers conically toward the outlet opening 48 to a narrowest cross-section 50, and then continuously widens, particularly in a trumpet-like manner, downstream of the narrowest cross-section 50 to a larger (e.g., 1.2 to 4 times) cross-section at the outlet card 52. Due to the particularly trumpet-like widening, the defined opening angle of the fuel cone can be maintained even at comparatively low mass flows.

[0049] The sharp exit edge 52 is achieved in particular by ensuring that the angle between the converging wall surfaces at the exit edge 52 is less than 90°. In this way, initial atomization of the fuel at the exit edge 52 can be achieved.

[0050] During operation, the high pressure generates fuel droplets at the injector element 24, which, due to the swirl in a fuel cone 28 extending from the injection point 26, enter the nozzle channel 14. An opening angle a of the fuel cone 28 can, for example, be between 60° and 100°.

[0051] According to the invention, the feed device 1 has a film-laying device 18 arranged radially between the injector element 24 and the nozzle wall 16. The film-laying device 18 is sleeve-like, in particular cylindrical, and / or completely surrounds the injector element 24 in a radially circumferential manner.

[0052] Between the nozzle wall 16 and the radial outer side of the film-laying device 18, an outer channel 30 is formed, in which an outer stream 32 of the oxidizer 38 flows during operation. Radially inside the film-laying device 18, between the radial inner side of the film-laying device 18 and the injector element 24, an inner channel 24 is formed, in which an inner stream 36 of the oxidizer 38 flows during operation. The inner channel 24 extends from an upstream edge 22 to the injection point 26 of the injector element 24. The film-laying device 18 is arranged coaxially to the supply nozzle 10 and the injector element 24 for symmetrical flow guidance (see Fig. 2B). The film-laying device 18 is fastened to the nozzle wall 16 in particular by means of several fastening elements 40 arranged symmetrically to one another, e.g., three.The fastening elements 40 are preferably arranged as far upstream as possible on the film-laying device 18 in order to influence the flow at the injection point 26 and downstream thereof as little as possible. The fastening elements 40 can advantageously project radially on the inside of the film-laying device 18 in such a way that they also center the injector element 24.

[0053] As Fig. 2A further shows, the film-laying device 18 has an atomizing edge 20 at its downstream end. The wall of the film-laying device 18 tapers toward the atomizing edge 20 in order to achieve the sharpest possible edge for fine droplet atomization.

[0054] At its upstream end, the film-laying device 18 has an edge 22. The edge 22 is aerodynamically shaped, exemplified in Fig. 2A by a tapered wall of the film-laying device 18, in order to generate the lowest possible pressure loss and / or the lowest possible secondary flow (in particular, turbulence).

[0055] The film-laying device 18 is arranged axially within the feed nozzle 10 such that the injection point 26 lies between the atomizing edge 20 and the upstream edge 22 of the film-laying device 18. The axial length of the film-laying device 18, between the atomizing edge 20 and the edge 22, depends on various parameters. Firstly, inlet effects within the inner stream 36 should have at least largely subsided by the time the injection point 26 reaches. Furthermore, the distance between the injection point 26 and the atomizing edge 20 is preferably designed such that at least a portion of the fuel 27 impinges on the inside of the film-laying device 18, forming a fuel film. The distance is therefore designed with particular consideration of the opening angle α of the fuel cone 28. At the same time, the distance should be kept as small as possible to ensure a compact design of the feed device 1.

[0056] The distance between the atomizing edge 20 and the outlet opening 12 of the supply nozzle 10 can be varied depending on the desired combustion pattern, for example, between 0 mm (axial position of the atomizing edge 20 on the outlet opening 12, corresponding to "direct injection") and, for example, up to ten times the diameter of the nozzle channel 16. A particularly compact design of the supply device can be achieved by arranging it as far downstream as possible. Depending on the upstream positioning, the combustion process, for example, the flame length, can be influenced.

[0057] The radial distance between the nozzle wall 16, the film-laying device 18, and the injector element 24 is determined by an advantageous flow design. The outer channel 30 and the inner channel 34 are designed relative to one another such that, during operation, the entire oxidizer flow flowing through the nozzle channel 14 is divided according to an advantageous ratio ("air split"). It has proven particularly advantageous if the velocity of the outer flow 32 is, for example, a factor of between 1.3 and 7 greater than the velocity of the inner flow 36.Three design factors in particular are taken into account: high shear between the outer stream 32 and the inner stream 36 for advantageous atomization at the atomization edge 20, a high external momentum from the outer stream 32 downstream of the atomization edge 20 to avoid wetting of the nozzle wall 16 with fuel, and a sufficiently high velocity of the inner stream 36 to propel the fuel film within the film-forming device 18 to the atomization edge 20. The design is carried out in particular using computer-aided fluid dynamics (CFD) and / or experimentally. During operation, oxidizer 38 flows from the distributor side 2 into the feed nozzle 10. At the film-forming device 18, the total oxidizer flow is divided into the outer stream 32 flowing through the outer channel 30 and the inner stream 36 flowing at a lower velocity through the inner channel 34.

[0058] The fuel 27 is introduced into the injector element 24 at a high relative fuel pressure (e.g., between 1 and 100 bar). The fuel 27 flows through the inlet openings 45 into the swirl chamber 47. Through the inlet openings 45 and / or within the swirl chamber 47, the fuel is set into rotation with an axial and a tangential velocity component, e.g., by means of (optionally present) guide bodies, and thus flows to the outlet opening of the injector element 24. The injection point 26 is located at the outlet opening 48 of the injector element 24. The swirl flow downstream of the injection point 26 causes the radial directional component of the fuel flow for the conical introduction of the fuel 27 into the feed nozzle 10 within the film-forming device 18.

[0059] At the injection point 26, fuel 27 is atomized at the exit edge 52 and injected into the fuel cone 28 with an opening angle a between 60° and 100°, e.g., 90°. A portion of the fuel 27 impacts the inside of the film-laying device 18 a few millimeters (e.g., between 2 mm and 10 mm) upstream of the atomization edge 20, forming a fuel film (film of fuel 27) on the inside of the film-laying device 18. The other portion of the atomized fuel 27 follows the internal flow 36 without contact with the film-laying device 18.

[0060] The inner stream 36 propels the fuel film to the atomization edge 20. At the atomization edge 20, the inner stream 36 and the outer stream 32 collide, forming a shear layer due to the velocity difference. At the sharp atomization edge 20, the high momentum of the oxidizer stream and the shear layer utilizing the fuel film are atomized into fine droplets, which are carried further downstream with the oxidizer stream toward the outlet opening 12.

[0061] The comparatively high momentum of the outer flow 32 ensures that the fuel droplets do not wet the nozzle wall 16, but are carried as completely as possible into the combustion chamber 3 with the oxidizer flow. The combustion of the oxidizer-fuel mixture takes place in the combustion chamber 3.

[0062] The two-stage atomization, with the first atomization at the outlet edge 52 of the injector element 24 and the second atomization at the atomization edge 20, results in a fuel 27 that is advantageously atomized upon entry into the combustion chamber 3. The first atomization contributes in particular to the formation of a uniform fuel film on the inner circumference of the film-laying device 18.

[0063] Investigations by the inventors at ten different average flow velocities of the oxidizer flow at the outlet opening 12, from 70 m / s to 160 m / s, have shown, for example, a very small droplet diameter across the entire feed nozzle 10. Specifically, 20 droplets with Sauter diameters (D32 iCharacteristic droplet diameters) between just under 10 pm and just under 30 pm are measured across the radius of the feed nozzle 10. This allows for advantageous evaporation and emission characteristics of the burner system 4.

[0064] The inventors' investigations have shown that the advantageous operation is possible with the above-described structure of the feed device 1 in a comparatively very compact structure.

[0065] For example, a single supply device can be designed for operation at a thermal power of, for example, between 5 kW and 30 kW (scaling up or down is possible). This allows for applications with comparatively moderate power density and / or moderate energy requirements (e.g., in decentralized energy conversion) as well as applications with a high required power and / or power density (e.g., aviation applications), for example, using a plurality of supply devices 1 in a burner system 4.

[0066] In summary, by means of the above-mentioned advantageous measures (individually or in combination) for forming a single supply device 1, a burner system designed according to the concept of the recirculation-stabilized jet flame burner for unswirled high-speed combustion can also be operated stably, reliably and with low emissions with liquid fuels having a comparatively short flame length, whereby a compact burner system can be provided.

Claims

Claims 1. Feed device (1), in particular for use in a gas turbine, for swirl-free supply of oxidizer (38) and fuel (27) into a combustion chamber (3), comprising - a feed nozzle (10) with a nozzle channel (14) enclosed by a nozzle wall (16) and aligned along a longitudinal axis (L), in particular cylindrical, which opens into a combustion chamber-side outlet opening (12) adjacent to the combustion chamber (3), and - an injector element (24) for adding the fuel (27) into the nozzle channel (14) at an injection point (26), characterized in that the injector element (24) is designed for adding liquid fuel (27) and that a film laying device (18) surrounding the injector element (24), in particular cylindrical, is arranged radially between the injector element (24) and the nozzle wall (16), wherein an outer channel (30) is formed between the nozzle wall (16) and the radial outer surface of the film laying device (18).

2. Feed device (1 ) according to claim 1 , characterized in that an inner channel (34) is formed radially within the film laying device (18), in particular between the radial inner side of the film laying device (18) and the injector element (24).

3. Feeding device (1 ) according to claim 1 or 2, characterized in that the film laying device (18) has constant external dimensions, in particular a constant internal diameter and / or external diameter, at least over a large part of its axial length. Feeding device (1) according to one of the preceding claims, characterized in that the film laying device (18) has an atomizing edge (20) at its downstream axial end, wherein, in particular, the wall of the film laying device (18) tapers towards the atomizing edge (20). Feeding device (1) according to one of the preceding claims, characterized in that the injector element (24) is elongated and / or projects into the feed nozzle (10), wherein, in particular, the injector element (24) has a cross-section that is at least substantially cylindrical and / or constant, at least within the feed nozzle (10) and / or the film laying device (18). Feeding device (1) according to one of the preceding claims, characterized in that the feed nozzle (10), the film laying device (18), and the injector element (24) are arranged coaxially with respect to the longitudinal axis (L).A feed device (1) according to one of the preceding claims, characterized in that the injection point (26) of the fuel (27) is arranged at the downstream end of the injector device (24) and / or centrally on the longitudinal axis (L). A feed device (1) according to claim 7, characterized in that the injection point (26) of the injector device (24) is arranged axially between the atomizing edge (20) and an upstream edge (22) of the film laying device (18). A feed device (1) according to one of the preceding claims, characterized in that the injector element (24) is configured for adding a fuel cone (28) with an opening angle (a) between 40° and 120°, in particular between 60° and 100°. A feed device (1) according to one of the preceding claims, characterized in that the injector element (24) is configured as a pressure-swirl injector, wherein a swirl generator (46) for imprinting swirl during fuel injection is arranged in the injector element (24). Supply device (1 ) according to one of the preceding claims, characterized in that at an outlet opening (48) of the injector element (24) a flow cross-section initially tapers, in particular conically, to a narrowest cross-section (50), and widens continuously, in particular trumpet-like, downstream of the narrowest cross-section (50) to a larger cross-section at the transition into the supply nozzle (10).A supply device (1) according to claim 11, characterized in that a circumferential, sharp exit edge (52) is formed at the outlet opening (48) of the injector element (24) at the transition to the supply nozzle (10). A supply device (1) according to any one of claims 4 to 12, characterized in that the distance between the injection point (26) and the atomizing edge (20) is designed such that at least a portion of the fuel is supplied during operation. on the inside of the film laying device (18) forming a fuel film. Feed device (1) according to one of the preceding claims, characterized in that the outer channel (30) and the inner channel (34) are designed to be coordinated such that, during operation, the entire oxidizer flow through the nozzle channel (14) splits into an outer flow (32) and an inner flow (36), wherein the velocity of the outer flow (32) is greater than the velocity of the inner flow (36), e.g., by a factor between 1.5 and 7, preferably between 2 and 5. Feed device (1) according to one of the preceding claims, characterized in that the feed nozzle (10) has no reduction in the flow cross-section at and / or downstream of the film laying device (18), in particular at and / or downstream of the atomizing edge (20).Feed device (1) according to one of the preceding claims, characterized in that the film laying device (18) is attached to the nozzle wall (16) by means of several, e.g., three, fastening elements (40), which center the injector element (24) in particular on the radial inner side of the film laying device (18). Feed device (1) according to one of the preceding claims, characterized in that the feed nozzle (10) for adding oxidizer and liquid fuel to the combustion chamber (3) is designed with a high axial impulse, wherein a mean flow velocity at the outlet opening (12) is between 60 m / s and 160 m / s, in particular between 80 m / s and 140 m / s. A feed device (1) according to one of the preceding claims, characterized in that the feed device (1) is designed for operation at a thermal output of 1 kW to 50 kW, for example between 10 kW and 20 kW. A feed device (1) according to one of the preceding claims, characterized in that the atomizing edge (20) is arranged near or at the axial height of the outlet opening (12). A burner system (4) with a burner head (7) comprising at least one feed device (1) according to one of the preceding claims and an end plate (6) through which the at least one feed device (1) opens into a combustion chamber (3) of the burner system (4), wherein the burner system (4) is designed for operation with a large-scale, combustion chamber-internal recirculation induced by the axial impulse of the incoming oxidizer fuel jets to stabilize a combustion zone in the combustion chamber (3).Method for swirl-free supply of oxidizer (38) and fuel (27) into a combustion chamber (3) by means of a supply device (1) according to one of claims 1 to 19, wherein liquid fuel (27) is added to an oxidizer (38) within a film laying device (18) arranged in a supply nozzle (10).

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