FI3584501T3 - Burner system and method for generating hot gas in a gas turbine plant - Google Patents

Description

Burner system and method for generating hot gas in a gas turbine plant

Description

The invention relates to a burner system for generating hot gas in a gas turbine plant, having a combustion chamber which comprises a combustion space oriented along a longitudinal axis, and having a burner head which has at least one oxidizer/fuel supply arrangement for supplying oxidizer and fuel into the combustion chamber as fresh gas components, comprising one flow path in each case for fuel and oxidizer for supplying them into the combustion space, the flow paths upstream of a mixing space each having separate flow portions for separately guiding the fresh gas components, and the flow paths being combined in the mixing space, and at least one first supply opening for supplying fuel into the mixing space. The invention further relates to a corresponding method for generating hot gas in a gas turbine plant.

A burner system of this kind is disclosed for example in WO 2014/027005 A2.

In recent years there has been an increasing interest in making use of energy of further fuels having different compositions, in addition to conventional fuels such as natural gas. Fuels of this kind are for example synthesis gas from biomass gasification, sewage gas, landfill gas, biogas, mine gas, or associated gas. The energetic use of the fuels can take place for example in gas turbine plants, in particular in micro gas turbine plants, the fuels being converted, in a combustion process, to a hot gas having hot exhaust gas. For this purpose, the fuels have to be combusted reliably, efficiently, and in a low-emission manner.

The different fuels may differ significantly in their composition. Thus, for example natural gas has a high portion of methane as a component, while a typical synthesis gas generally contains, in addition to hydrogen and optionally further combustible components (e.g. carbon monoxide, methane), a high inert gas portion (in particular carbon dioxide and nitrogen). Therefore, the fuels exhibit differences in their combustion properties, such as flame speed and ignition delay time, and in their calorific values or their Wobbe index (as a variable for assessing the compatibility of fuel gases). Thus, for example natural gas, having a mass-specific calorific value of just below 50 MJ/kg, is to be allocated to the high

calorific fuels, whereas a typical synthesis gas, as a low-calorific fuel, can for example have a mass-specific calorific value of approximately 5 MJ/kg or below. Mid-calorific fuels exhibit calorific values between these extremes. Thus, when using a low-calorific synthesis gas of this kind, a fuel mass flow approximately ten times larger, compared with - high-calorific - natural gas, is required in order to achieve a corresponding output. These different properties make it more difficult to use different fuel qualities in a single burner system.

A known approach for using both high-calorific and low-calorific fuels in a single-burner system is the separate introduction of said fuels. In this case, the different fuels are introduced via separate feeds, which are each designed for the particular properties of the fuel. Another approach is the exchange and/or the adjustment of the fuel nozzles or channels, while changing the geometry. However, this is complex and usually does not allow for adjustment during ongoing burner operation.

US Pat. No. 4,967,561 A discloses a burner system in which selectively a liguid or gaseous fuel can be introduced into a combustion chamber for combustion. For this purpose, the burner system comprises a radius of pipe bodies, inside which, for the purpose of pre-mixing, a liguid or gaseous fuel can be added into the combustion air, for pre-mixing, via — separate nozzles, which are different in the case of different fuels being added.

Burner systems, in particular for operation using mid- or low-calorific fuels, are disclosed in US 6 684 640 B2, DE 44 09 918 A1, EP 1 800 062 B1, EP 1 892 469 A1 and

EP 0 908 671 A1.

A burner system based on the principle of a recirculation-stabilized jet flame burner can be derived from EP 1 995 515 A1.

A mixing device for example for use in a recirculation-stabilized jet flame burner is specified in DE 10 2010 062 351 A1.

US 2004/068973 A1 discloses a burner comprising a loop of oxidizer-guiding channels of different burner stages, and one fuel channel. In order to adjust the fuel amounts inside the oxidizer-guiding channels, at different load ranges, the burner has what is known as a “fluid control construction”, which comprises an open region and a supply region. In this case, there is a different distribution of the fuel stream over the different burner stages, depending on a critical mass flow, in order to comply with the upper flammability limit.

US 2010/077759 A1 discloses a gas turbine burner comprising a primary fuel nozzle for a primary combustion chamber, and comprising a secondary fuel nozzle for a secondary combustion chamber. The secondary fuel nozzle comprises a pre-mixing portion, via which fuel can be added both through radial gas supplies and through a pilot hole of the combustion chamber, opening downstream of said gas supplies. A design for the operation using fuels of different calorific values is not specified.

JP 3 976464 B2 specifies a combustion chamber comprising a fluid mixer comprising a circle of supply openings. A design for the operation using fuels of — different calorific values is not specified.

EP 1 255 080 A1 relates to a catalytic burner designed as a swirl burner. A design for the operation using fuels of different calorific values is not specified. - [0014] US 2010/139238 A1 discloses a burner for operation using a low-calorific fuel, which can also be operated using a high-calorific fuel. The fuels having the different calorific values are introduced into the combustion chamber via different fuel supplies.

The object of the invention is that of providing a burner system and a method for - generating hot gas, which allow for reliable, low-emission and efficient operation using both high-calorific and low-calorific fuels, with comparatively low outlay .

The object is achieved by a burner system having the features of claim 1 or claim 2, or a method having the features of claim 17.

In the burner system according to claim 1 or claim 2, it is provided that the oxidizer/fuel supply arrangement comprises at least one further flow portion having a further supply opening, via which a portion of one of the fresh gas components for supplying into the combustion space can be supplied into a flow portion with the other fresh gas component, whereby the further flow portion is arranged and designed in such a way that, in the case of an unchanged geometry, the portion of the fresh gas component that flows via the further flow portion can be changed with the calorific value of the fuel, as a result of a changing pressure ratio.

The portion relates, for example, to the total mass or volume flow of the corresponding fresh gas flowing through the oxidizer/fuel supply arrangement. The further flow portion is arranged in particular such that the division of the corresponding fresh gas component stream into at least two portions takes place inside the burner head, i.e. the further flow portion branches off out of the separate flow portion(s) inside the burner head.

The flow portion comprising the other fresh gas component can for example be one of the flow portions of fuel or oxidizer upstream of the mixing space. For example, the flow — paths of the fresh gas components are guided separately, upstream of the further supply opening, and, downstream of the further supply opening, firstly combined in part, are guided in a common and a (still separate) flow portion , before they are combined completely, in the mixing space, as a common flow portion, again downstream of the first supply opening. The combining can thus take place in a stepped manner, in succession, the further supply opening being arranged upstream of the first supply opening. In particular, alternatively, the flow portion comprising the other fresh gas component can be formed by the mixing space, it being possible in particular for a portion of the fuel to flow into the mixing space via the separate flow portion comprising the first supply opening, and for the other portion to flow into said mixing space via the further flow portion (passable in parallel) and the further supply opening. In this case, the separate flow portion having the first supply opening, and the further flow portion, open into the mixing space in a manner in which they can be passed through in parallel. Both one and the other alternative can be provided in the same burner system.

In one variant comprising (at least partial) pre-mixing of the fresh prior to introduction into the combustion gases chamber, the mixing space is a part of the burner head, in particular the oxidizer/fuel supply arrangement, it forming a common flow portion. In one variant which is also possible, comprising introduction into the combustion chamber without pre-mixing, the mixing space corresponds to a region of the combustion space.

The first and the further supply opening can also be groups of first and further supply 5 openings (and/or flow portions associated therewith), which are arranged for example in different (flow) regions, the groups for example being designed in each case according to mutually corresponding design criteria, and/or fulfilling a mutually corresponding function.

In contrast, the first and the further supply opening(s) differ from one another for example by their design criteria and/or function.

The arrangement and/or design of the further flow portion is such that, in the case of introduction of fuels having a different calorific value (or a different Wobbe index), the portion changes, on account of changing aerodynamic ratios, in particular the pressure ratios. The geometry remains unchanged, in particular the flow cross sections of the flow — portions remain constant. A volume flow regulation by means of adjusting devices, in particular valves, can be omitted. The supply of different fuels can thus take place via the same oxidizer/fuel supply arrangements. This consequently allows the use of varying fuels and/or mixed operation, e.g. having a continuous change of the fuel composition, with little effort and during ongoing operation. - [0023] In a method for the design, for example the following process is possible in order to arrive at the burner system according to the invention: Proceeding from a known burner system of the type in guestion, one or more pair(s) of locations are located, within the separated flow portions of oxidizer and fuel, at which the pressure difference and/or the pressure ratio between a high-calorific and a low-calorific design point changes with — respect to the flow portion having the other fresh gas component (fuel or oxidizer) in each case. This can take place for example by pressure determination by means of computer-assisted flow simulation and/or experimentally, for example the mass or volume flows being set according to the design operating points. A/a forward of further flow portion(s) having a further supply opening is/are now arranged in a manner interconnecting said pair(s) of locations. The (respective) further flow portion is designed, arranged in particular and/or formed, according to the desired division or portions (e.g. having a corresponding flow cross section). In this case, for example (firstly) an approximate pressure loss calculation and/or (subseguently) an iterative approximation to the design aim can take place, for example by means of computer-assisted flow simulation and/or experimentally.

The design aim can for example be that of maintaining a particular velocity range among the various design points.

In a preferred variant, the design aim provided is that the portion should be variable in such a way that the velocities at the first and/or at the further supply opening deviate from each other, between a low-calorific design point and a high-calorific design point, at most by a factor of 2 (velocity in the case of low-calorific fuel to velocity in the case of high-calorific fuel), in particular at most by a factor of 1.5, preferably at most by a factor ofl.2, Le. the velocities are similar to one another in the different design points. The “low-calorific design point? corresponds to a design operating point having a low-calorific design fuel, for example a synthesis gas, having for example a mass-specific calorific value of approximately 5 MJ/kg. The *high-calorific design point? corresponds to a design operating point having a high-calorific design fuel, for example a natural gas, having for example a — mass-specific calorific value of almost 50 MJ/kg. The thermal outputs of the two design points preferably correspond to one another, these being specified on the machine side. In the case of a micro gas turbine arrangement, in which the burner system according to the invention can be used for example, the thermal output can be for example up to 1 MW or 500 kW, e.g. approximately 300kW. The air ratio or the combustion air ratio corresponds for example to that in a known burner system of the type in question, and can be for example between 1.4 and 3.4. The fuel compositions in the low-calorific and in the high-calorific design point preferably represent extremes with respect to the calorific value, between which the calorific values of the fuel compositions range during operation.

The similar velocities (as defined above) can be achieved by the design and/or arrangement — of the further flow portion having the further supply opening. The design is preferably carried out, as is conventional today, via computer-assisted flow simulation. This makes it possible for, in particular those velocities which have a decisive influence on the combustion process in the combustion chamber system, to remain similar to one another (at least to the extent mentioned above) in the event of different fuels. Thus, particular operating characteristics, for example the mixing (at least in part or in regions) of fuel into the oxidizer, at the two design points can be matched. This contributes to a stable, low-emission and efficient combustion process when using low-, mid- and high-calorific fuels.

In a preferred variant of the burner system according to claim 1, the oxidizer/fuel supply arrangement has an oxidizer channel having an outlet for opening into the combustion chamber, an outflow portion comprising the outlet, of the oxidizer channel being oriented along a central axis M which, substantially axially, extends in parallel with —the longitudinal axis. The oxidizer channel forms a flow path for oxidizer, which guides the oxidizer in a separated manner in an upstream portion. The end of the oxidizer channel directed upstream can in particular be in flow connection with an oxidizer distribution space of the burner head, such that the oxidizer channel forms a flow connection for the oxidizer between the oxidizer distribution space and the combustion space. The oxidizer channel — canin particular be designed in a nozzle-like manner. As a result of the axial arrangement, the oxidizer can be introduced into the combustion chamber at a high axial momentum, such that a marked recirculation zone is formed in the combustion space, which zone stabilizes the combustion, as is conventional in the case of a recirculation-stabilized jet flame burner (also known as a “FLOX burner”). An embodiment of this kind allows for a — stable, low-emission combustion process.

In a preferred variant of the burner system according to claim 1, the oxidizer/fuel supply arrangement has a fuel channel which is delimited by a wall, which channel is designed to extend in parallel with, in particular coaxially to, the oxidizer channel, at least with one end portion in the oxidizer channel, and which opens via a fuel opening within the oxidizer channel or at the outlet thereof, the fuel opening forming the first supply opening.

In the fuel channel, the separate portion of the fuel flow path is formed upstream of the fuel opening (and optionally upstream of the further supply opening). The fuel channel can in particular form a flow connection between a fuel distribution region and the mixing space.

Such an embodiment of the fuel channel comprising the fuel opening makes it possible for the fuel to be added into the air flow coaxially, which promotes symmetrical, uniform mixing of fuel into the oxidizer, and thus a uniform, stable combustion process with low emissions.

In a variant of the burner system according to claim 1, the fuel opening has a flow cross section, in particular having a diameter ds, which is reduced compared to the flow cross section, in particular having a diameter dz, of the fuel channel extending upstream.

The flow cross section of the fuel opening is preferably designed such that a velocity similar to the velocity of the fresh gases at the outlet of the oxidizer channel into the combustion chamber results there in the high-calorific design point. In this case, “similar” means for example between +/- 50%, preferably between +/- 20%, particularly preferably between +/- 10% of the velocity at the outlet. The similar velocity brings about high stability in the case of fuel being mixed in, preventing separations, which can lead to unstable combustion or even to thermoacoustic oscillations.

Alternatively, the fuel opening has a flow cross section, in particular having a diameter d3, which corresponds to the flow cross section, in particular having a diameter —d>, of the fuel channel extending upstream. The flow cross section is for example such that a velocity similar (as defined in the above paragraph) to that of the fresh gases at the outlet of the oxidizer channel is set there at the low-calorific design point, with the above-mentioned advantages .

In the case of the burner system according to claim 1, the further supply opening is formed by at least one bypass opening, the bypass opening being formed upstream of the fuel opening in the wall, and the further flow portion forming a flow connection between the flow paths of the oxidizer and the fuel. In the event of a fresh gas component (fuel or oxidizer) flowing through the bypass opening, the bypass opening serves for partially combining the fresh gases upstream of the fuel opening. The separated flow portions of the flow path are then located upstream of the bypass opening. The complete combining of the fuel and oxidizer preferably takes place further downstream of the fuel opening. It has been found that, on account of such an arrangement of the bypass opening, upstream of the fuel opening, the mass or volume flow which flows through the fuel opening can usually be equalized, at least in part, between the high-calorific and the low-calorific design point. In this way, it is possible for similar velocities at the fuel opening to be achieved in the low- and high-calorific design point, which velocities deviate from one another for example by less than a factor of 2, in particular by less than 1.5, preferably by less than 1.2. It is thus possible for similar inflow and mixing characteristics to be achieved in the two design points, which characteristics form a prerequisite for stable, efficient and low-emission operation.

In the case of the burner system according to claim 1, the flow cross section of the fuel opening is preferably designed in such a way that, at the low-calorific design point or at the high-calorific design point, the velocity at the fuel opening is between +/- 50%, preferably between +/- 20%, of the velocity of the fresh gas mixture at the outlet into the combustion space, the portion flowing through the bypass opening being (at least — substantially) equal to zero. At the corresponding design point an operation is then possible in which, as is known from the prior art, the fuel and oxidizer flows flow separately as far as the fuel opening and are (completely) combined there. This prohibition allows for a simple design, proceeding from a configuration (e.g. known from the prior art) without a bypass opening. The flow portion comprising the bypass opening is designed (formed and/or arranged) such that in the case of a different fuel (which has a different calorific value), a portion of fuel or oxidizer can flow through the bypass opening and in each case into the flow path having the other fresh gas component. Differences in the fuel volume flows can be compensated, at least such that the velocity at the fuel opening remains in a similar range, as stated above. The design is typically carried out using computer-assisted flow simulation.

For example, the following advantageous procedure results in the case of a design proceeding from the low-calorific design point, the fuel opening expediently having a flow cross section corresponding to the fuel channel: At the low-calorific design point, having the high fuel mass or volume flow, fuel and oxidizer flow separately as far as the fuel opening, and are completely combined there. The pressure ratios in the oxidizer and fuel channel are similar, at the low-calorific design point, such that the portion of fresh gas, in this case oxidizer, flowing through the bypass opening is (substantially) zero. At the high-calorific design point, having the low fuel mass or volume flow, a smaller pressure loss then results in the fuel channel than in the oxidizer channel. This results in a pressure difference between the oxidizer and the fuel channel. The pressure difference brings about a flow of oxidizer in the fuel channel through the bypass opening, such that the pressure ratios are equalized. As a result of this oxidizer portion, the mass or volume flow in the fuel channel, downstream of the bypass opening, is increased, while the oxidizer flow is reduced. The further flow portion comprising the bypass opening, in particular the angle and flow cross section thereof, are designed such that the portion of oxidizer flowing through the bypass opening comes about in such a way that the velocity at the fuel opening is similar, compared with the low-calorific design point (as stated above), associated with the advantages set out above. In particular, the total flow cross section of the bypass opening and/or of the further flow portion is less than the smallest flow cross section in the fuel channel (comprising the fuel opening), e.g. between 10 and 70% with respect to the smallest cross section. The portion of oxidizer can for example result such that the oxidizer mass flow through the bypass channel corresponds to up to 5 times the fuel mass flow. It has been found that, in the case of fuel compositions having a calorific value or Wobbe index between that of the low and of the high-calorific fuel, a correspondingly smaller portion is established, which leads to the similar velocities.

In the case of a design proceeding from the high-calorific design point the following advantageous procedure results, the fuel opening expediently having a reduced flow cross section of the fuel opening compared with the fuel channel: At the high-calorific design point , having the low fuel mass or volume flow, fuel and oxidizer flow separately as far as the fuel opening, and are completely combined there. The pressure ratios in the oxidizer and fuel channel are similar at the high-calorific design point. Furthermore, on account of the oxidizer flowing around the fuel channel, an aerodynamic obstruction of the further flow portion comprising the bypass opening results. As a result, the portion of fresh gas, in this case fuel, flowing through the bypass opening is (substantially) zero. At the low-calorific design point, having the high fuel mass or volume flow, a higher pressure loss results in the fuel channel than in the oxidizer channel, in particular on account of the reduced flow cross section of the fuel opening. This results in a pressure difference between the oxidizer and the fuel channel, which brings about a flow of fuel into the oxidizer channel via the bypass opening, such that the pressure ratios equalize. As a result of the fuel portion flowing out, the mass or volume flow in the fuel channel, downstream of the bypass opening, is reduced, while the volume flow in the oxidizer channel is increased. The further flow portion comprising the bypass opening, in particular the angle and flow cross section thereof, are designed such that the portion of oxidizer flowing through the bypass opening comes about in such a way that the velocity at the fuel opening is similar, compared with the high-calorific design point (as stated above). In particular, the total flow cross section of the bypass opening and/or of the further flow portion is less than the smallest flow cross section in the fuel channel. The portion can for example be between 30% and 90% of the total fuel mass flow. It has been found that, in the case of fuel compositions having a calorific value between that of the low and of the high-calorific fuel, a correspondingly smaller portion is established, which leads to the similar velocities.

If a round of flow portions are present, which are in particular symmetrical to one another, e.g. are arranged rotationally symmetrically about the central axis and axially at the same height, a symmetrical introduction of one fresh gas component into the other fresh gas component can be achieved. This contributes to a uniform mixing, which in turn promotes low-emission combustion. - In the case of the burner system according to claim 1, the bypass opening is preferably arranged axially inside (or with respect to) the oxidizer channel downstream of an inflow portion of the oxidizer channel, which preferably has such an axial length that inlet effects of the oxidizer flow in the case of inflow into the oxidizer channel, in particular local flow separations, have substantially subsided at the bypass opening. In this case — *substantially” means that the inflow into or out of the bypass opening is not significantly influenced by transient flow phenomena. Furthermore, an arrangement in the oxidizer channel reduces the risk of a return flow of fuel into an oxidizer distribution space, as could arise for example in the case of a brief flow reversal in transient states (for example ignition procedures, etc.). For example, the length of the inflow portion can correspond at least to the diameter of the bypass opening.

In the case of the burner system according to claim 1, the bypass opening is preferably arranged axially inside (or with respect to) the oxidizer channel upstream of an outflow portion of the end portion (of the fuel channel), which preferably has such an axial length that inlet effects in the case of inflow of one fresh gas component through the bypass opening have substantially subsided by the time the fuel opening is reached. In this case "substantially" means that the flow out of the fuel opening is not significantly influenced by transient flow phenomena. It is thus possible to achieve uniform, stable mixing of the (optionally remaining) fuel into the oxidizer, in the downstream mixing space. The length — of the outflow portion can, for example, be at least 0.5 times the inner diameter of the fuel channel. The length of the inflow and/or of the outflow portion can in particular be designed using computer-assisted flow simulation.

The desired flow guidance, having the desired portion flowing through the bypass opening, can be promoted in that the further flow portion comprises a bypass channel in the wall, which channel extends radially-axially at an angle with respect to the central axis (of the fuel channel). The bypass channel opens into the bypass opening, downstream. In this way, a flow direction of one fresh gas component into the other, which does not correspond to the design, is of course impeded.

In this case, it may be advantageous, in a variant, for the angle to be between 0* and 90°, in particular between 10° and 60°, e.g. between 15° and 45°. The angle is measured — between the bypass channel longitudinal axis and the central axis (with respect to the limb of the central axis facing upstream). This embodiment promotes a (possibly optional) flow of the oxidizer into the fuel channel, and impedes a flow of fuel towards the outside, into the oxidizer. This embodiment of the bypass channel is for example expedient in combination with a flow cross section of the fuel opening corresponding to the fuel channel, which allows for an advantageous design proceeding from the low-calorific design point.

In an alternative variant, it may be advantageous for the angle to be between 90° and 180°, in particular between 110° and 170°, e.g. between 130° and 165°. This embodiment promotes a flow (optional, depending on the design) of the fuel into the oxidizer channel, and impedes a flow of oxidizer into the fuel channel. This embodiment of the bypass channel is for example expedient in combination with a reduced flow cross section of the fuel opening compared with the fuel channel, which allows for an advantageous design proceeding from the high-calorific design point. - In the case of the burner system according to claim 1, the oxidizer channel preferably comprises, in the axial course thereof, a first portion, and a second portion downstream of the first portion, a reduction in cross section being arranged between the two servings. In this case, the fuel opening is arranged axially at, within or downstream of the reduction in cross section. The reduction in cross section can be formed for example as a jump, — conically, or continuously. This arrangement of the fuel opening results in the (complete) addition of the fuel into the flow accelerated directly downstream, or into the already accelerated flow. This business counteracts an (undesired) flame stabilization at the fuel opening.

In the case of the burner system according to claim 2, the oxidizer/fuel supply arrangement has a (possibly further) mixing space, which is arranged centrally on the longitudinal axis and is symmetrical with respect to said axis. The mixing space is delimited on the bottom by a bottom wall, oriented for example perpendicularly to the longitudinal axis L, and on the periphery by a wall, and is for example cylindrical. The mixing space opens, downstream, via an outlet into the combustion space. The fresh gas components can be supplied to the mixing space in such a way that a swirling (or rotational) flow having a tangential directional component is generated. The oxidizer/fuel supply arrangement thus comprises a swirl burner arrangement. The oxidizer/fuel supply arrangement can be assigned to a single-stage burner system or with a multistage, in particular a 2-stage system, it being possible in particular for the oxidizer/fuel supply arrangement to be assigned to a pilot stage. A combination with a twist of oxidizer/fuel cell arrangements according to one of the above variants, in particular as the main stage, is particularly advantageous. The cross section of the mixing space perpendicular to the longitudinal axis is preferably smaller than that of the combustion space. The length of the mixing space in the axial direction is at least so great that fresh gas openings can be made on the periphery, and preferably that at least partial pre-mixing of the fresh gas components, up to the outlet, results. The mixing space, just like the combustion chamber (in particular in the case of assignment to a pilot stage), can be installed for example in a burner head member.

In the case of a burner system according to claim 2, the oxidizer/fuel supply arrangement has at least one oxidizer channel which opens into the mixing space on the periphery and which is oriented with a tangential (and optionally a radial) directional component with respect to the longitudinal axis, the oxidizer channel being assigned to the separate flow portion of the oxidizer. The oxidizer channel forms for example a flow connection between the air distribution space and the mixing space. For the purpose of uniform, symmetrical introduction into the mixing space, preferably a model of oxidizer channels, for example three, are present, which are in particular arranged rotationally symmetrically about the longitudinal axis. In the case of a rush of oxidizer channels being present, these extend and open for example axially at the same height, in a plane located perpendicularly to the longitudinal axis. A rotational movement, for swirl generation, can thus be imposed effectively on the oxidizer flow.

In the case of the burner system according to claim 2, in an advantageous variant a distribution region for fuel is assigned to the oxidizer/fuel supply arrangement, which region is arranged in particular symmetrically with respect to, e.g. centrally on, the longitudinal axis (or the longitudinal axis and/or axis of symmetry of the mixing space) and/or adjacent to the rear of the bottom wall. The distribution region is arranged for example in a burner head member. In particular, the cross-sectional area (perpendicularly to the longitudinal axis) of the distribution region can be radially the same as or larger than that of the mixing space. An effective cooling of the underside of the mixing space by the inflowing fuel can thus be achieved. In particular in conjunction with a fuel supply arranged centrally on the longitudinal axis, which supply introduces the fuel into the distribution region for example perpendicularly to the bottom wall, the fuel can strike the bottom wall and thus bring about effective impact cooling.

An advantageous operation in particular using low-calorific fuel is achieved in the burner system according to claim 2 in that the first supply opening is formed by at least one first fuel opening, which opens into the mixing space on the periphery and which forms the downstream end of a first fuel channel, an end portion of the fuel channel extending with a tangential (and optionally radial) directional component with respect to the longitudinal axis. Preferably, the end portion of the fuel channel is aligned to the oxidizer channel, i.e. with a corresponding tangential and optionally radial directional component. In this way, the fuel flow can contribute to generating the swirling flow, which leads to a comparatively small pressure loss. The fuel channel preferably forms a flow connection between the distribution region and the mixing space. Upstream of the end portion, the fuel channel is for example oriented axially with respect to the flow connection to the distribution region.

In this case, preferably, in particular in the case of the presence of a spray of oxidizer and/or fuel channels, an oxidizer opening of the oxidizer channel and the first fuel opening are arranged axially offset from one another, the axial lower edge of the oxidizer — opening being arranged upstream of the axial lower edge of the fuel opening. In this case, the lower edge of the oxidizer opening can, for example, be flush with the bottom of the bottom wall. In this way, the fuel flow can be carried along by the swirling oxidizer flow.

In the event of a flame stabilization in the mixing space, a certain spacing from the bottom wall is retained, and in particular the thermal load of the bottom wall is reduced due to the air flow located therebetween. Three channels, respectively, have been found to be an advantageous number of oxidizer and fuel channels, which channels open alternately into the mixing space, on the periphery, and are arranged rotationally symmetrically with — respect to the longitudinal axis, offset by 60° in each case. This makes it possible for good mixing of the fresh gases into one another, with effective swirl generation.

Alternatively or in addition, the total flow cross section of the first fuel opening is designed in such a way that the inflow velocity of the fuel into the mixing space at the low-calorific design point is between 10% and 120%, in particular between 15% and 80%, of the inflow velocity of the oxidizer at the oxidizer opening. The velocity of the oxidizer is such that a sufficient swirl generation for flame stabilization is achieved, and can for example be between 50 m/s and 120 m/s. The total flow cross section results from the sum of the flow cross sections of particular flow portions or openings, in this case the present — first fuel openings. As a result, the momentum of the high fuel mass or volume flow can contribute effectively to the swirl generation. Furthermore, braking of the rotational movement of the oxidizer flow by the high fuel flow is prevented, which braking could impair the flame stabilization. - In the case of the burner system according to claim 2, the further supply opening is formed by a second fuel opening into the mixing space, and the further flow portion comprises a second fuel channel which is oriented with an axially directional component , e.g. parallel, with respect to the longitudinal axis. Preferably a higher of second fuel openings and channels may be provided, for uniform introduction of fuel. The total flow cross section of the second fuel opening is preferably that the velocity at the high-calorific design point is e.g. between 30% and 80% of the velocity of the oxidizer at the oxidizer opening. In particular, the total flow cross section of the second fuel opening and/or the second fuel channel is smaller than the (total) flow cross section of the first fuel channel, and is e.g. between 4% and 40% of the total flow cross section of the first fuel channel. In addition, the channels can comprise a radial directional component. The channels, likewise the fuel and oxidizer channel, can for example be formed by a drilled hole that is circular in cross section. It is thus possible for an increase of separate flow portions, through which fuel can flow in parallel, to be provided, through which flow portions different portions of the fuel flow, depending on the calorific value of the fuel. In this way, an operation using high-, mid- and also low-calorific fuels is made possible, in each case good mixing-in of the fuels and stable combustion being achievable.

In the case of the burner system according to claim 2, the second fuel opening is preferably arranged in the mixing space at a location at which there is a lower pressure at a high-calorific design point (or in the case of a pure oxidizer flow) than at a location of the first fuel opening. The location can, in particular in the case of an image of (first and/or second) fuel openings being present, also be a region. The pressure can for example be — between 0.1% and 2% lower than at the location of the first fuel opening. In this way, a separation of the fuel flow can be achieved aerodynamically, which separation changes as the calorific value changes, such that, for different fuel qualities, good mixing and sufficient swirl generation for stable combustion can be achieved: at the high calorific design point, (virtually) the entire fuel flow (a portion of approximately 100%) flows into the mixing space via the second fuel channel (or fuel channels). This is brought about by the pressure difference, which is larger over the second fuel channel than over the first fuel channel, and by an aerodynamic blocking effect of the swirling oxidizer flow with respect to the first fuel openings. The aerodynamic ratios largely prevent a flow of the high-calorific fuel via the first fuel channel/fuel channels, which, on account of the low momentum of the high-calorific fuel, would not mix sufficiently into the oxidizer swirling flow. The comparatively small axial mass flow of the high-calorific fuel can be accelerated and carried along by the rotational movement of the air, such that stable combustion can be achieved. The total flow cross section (sum of the flow cross sections) of the second fuel channels is substantially smaller than the total flow cross section of the first fuel channels. The total flow cross section is smaller to such an extent that a pressure loss would result, at the low-calorific design point having the high fuel mass or volume flow (fuel flow for short), which pressure loss is higher than the pressure difference on account of the arrangement of the second fuel openings. As a result, one portion (for example more than 30%, in particular more than 50%) of the fuel flows via the first fuel channel/fuel channels, and the remaining portion flows via the second fuel channel/fuel channels. In this way, the high fuel flow at the low-calorific design point promotes the rotational movement. If the entire fuel flow at the low-calorific design point were introduced via axial fuel channels, the rotational momentum of the air would not be sufficient for maintaining the rotational movement to such an extent for stable combustion to be achieved.

In a variant according to the burner system according to claim 2, which is - particularly simple to produce, the second fuel channel forms a flow connection between the distribution region and the mixing space and extends through the bottom wall, the second fuel opening in particular being positioned so as to be axially level with the surface of the bottom wall on the mixing space side. For example, the second fuel opening is arranged so as to be radially offset from the central axis, for example between 1/4 and 3/4 of the diameter of the mixing space. This is advantageous in particular in the case of a future of fuel openings being present, which openings are preferably arranged symmetrically about the central axis. In the case of just one fuel opening, this can be arranged on the central axis.

An advantageous burner system which allows for stable operation over a wide - operating range using high-, mid- and low-calorific fuels results if at least two oxidizer / fuel arrangements are provided, one, preferably one thereof, being designed for flame stabilization in the manner of a recirculation-stabilized jet flame burner (preferably as a main stage), and one being designed for flame stabilization via a swirling flow (preferably as a pilot stage) The oxidizer channels are preferably fed via a common oxidizer distribution space, while the fuel channels are associated with separate distribution regions.

Advantageous variants of the method correspond, accordingly, to the variants which were described in connection with the burner system according to either claim 1 or claim 2.

The invention will be explained in greater detail in the following on the basis of this and with reference to the drawings, in which:

Fig. 1: is a longitudinal sectional view of a burner system of a gas turbine arrangement for operation using low-, mid- and high-calorific fuels, comprising two oxidizer/fuel supply arrangements according to the invention,

figs 2 AC: are schematic views, in longitudinal section, of a part of the oxidizer/fuel supply arrangement for axial oxidizer supply into a combustion chamber according to Fig. 1, without flow guidance and with flow guidance indicated, at two different operating points,

figs 3 A-C: are schematic views, in longitudinal section, of a part of a further variant of an oxidizer/fuel supply arrangement for axial oxidizer supply into a combustion chamber, without flow guidance and with flow guidance indicated, at two different operating points,

Fig. 4: is a schematic front view, from the direction of a combustion chamber, of a burner head of the burner system according to Fig. 1 comprising the two oxidizer/fuel supply arrangements,

Fig. 5: is a perspective sectional view, through the oxidizer and fuel channels, of a part of a burner head according to Fig. 4, comprising an oxidizer/fuel supply arrangement for swirl generation, and

figs 6 A and B: are schematic views, in longitudinal section, of a part of the oxidizer/fuel supply arrangement according to Fig. 5, during operation in the case of two different operating points.

Fig. 1 is a longitudinal sectional view of a burner system 1 of a gas turbine arrangement, in particular a micro gas turbine arrangement, for operation using low-, mid- and high-calorific fuels. In the burner system 1, during operation, oxidizer and fuel are combusted in order to form hot gas as a working medium for the gas turbine arrangement.

The oxidizer is generally formed by air, which can also contain further components, e.g. externally recirculated exhaust gas or thermally exploitable hydrocarbons. An oxygen-containing exhaust gas is also possible. In the following, the designation “air” is used — synonymously for the more general term “oxidizer”.

The burner system 1 extends along a longitudinal axis L, which in this case, by way of example, represents the axis of symmetry. As indicated in Fig. 1, the burner system 1,

together with a combustion chamber 6, is installed in a combustion pressure housing, more precisely in a pressure housing space 12 surrounded by a pressure housing wall 10, in a gas turbine arrangement. The pressure housing is connected for example in a pressure-tight manner to a turbine housing (not shown here).

The combustion chamber 6 comprises a combustion space 24 which extends along the longitudinal axis L and is delimited by a peripheral wall 20. In the present case, the peripheral wall 20 is, by way of example, designed cylindrically, which is advantageous for a symmetrical, uniform, and thus low-emission, combustion process. At the downstream end of the combustion space 24, the peripheral wall 20 ends in an outlet opening 22, via which the combustion chamber 6 is connected to an exhaust gas line 8 of the gas turbine arrangement.

Mixed air openings 18 are made all around the peripheral wall 20, which openings are arranged axially in the peripheral wall 20, such that they are located downstream of a combustion zone during operation.

The peripheral wall 20 extends coaxially with respect to an outer wall 14 of the combustion chamber 6, which is arranged around the peripheral wall 20, forming a - peripheral, in this case annular, gap. The gap forms a feeder channel 16 for counterflow-like supply of air into an air distribution space 30 of a burner head 4. A different design of the air supply is also possible.

The burner head 4 of the burner system 1 is arranged on the combustion chamber 6, on the upstream side. The burner head 4 comprises a carrier plate 32, into which a distribution region 38 for the fuel of the main stage is integrated. In this case, the distribution region 38 is formed, by way of example, as an annular plenum, annularly all around the longitudinal axis L, and is fed by a fuel supply 34. The carrier plate 32 forms an end-face termination of the pressure housing space 12 and is connected to the pressure — housing wall 10 by means of fastening devices 31, for pressure-tight closure of the pressure housing space 12. A planar insulation means 33 of the burner head 4, for thermal insulation, is arranged between the carrier plate 32 and the pressure housing space 12 or the combustion chamber 6.

In this case, the burner head 4 comprises, by way of example, separate air/fuel supply arrangements 50, 60. The air/fuel supply arrangements 50 are associated with a main stage of the burner system 1, and serve for adding the fresh gas components air and fuel into the combustion chamber 24. In the present case there are, by way of example, ten air/fuel supply arrangements 50, which are arranged equidistantly on an imaginary circular ring for forming a nozzle ring. This arrangement contributes to a small axial extent of the combustion zone.

The air/fuel supply arrangement 60 is associated with a (stabilizing) pilot stage of the burner system 1, and serves for supplying the fresh gas components air and fuel into a second (pilot) combustion space 26. The second combustion space 26 is arranged upstream of the combustion space 24 and leads into the combustion space 24 with an opening 28, it being formed, in the present case, on the longitudinal axis L and symmetrically, in particular cylindrically, with respect thereto. The air/fuel arrangements 50 are arranged, — together with air channels 504, peripherally around the second combustion space 26. In this case, by way of example, the air channels 504 and the combustion space 26 are formed in a burner head member 25 made of solid material. Another design, for example having (thinner) walls, is also possible. At steady operating points, the greater air and fuel mass flows are generally guided via the main stage.

A fuel supply line system 2 of the burner system 1 serves for separate supply of fuels for the main and pilot stage into the distribution region 38 of the main stage, via the fuel supply 34, and into a second distribution region 40 of the pilot stage via a second fuel supply 36. The fuel mass flows are preferably separately controllable, it also being possible for different fuels to be used.

The first air/fuel supply arrangements 50 are designed to introduce the fresh gas components air and fuel into the combustion space 24 axially, in parallel with the longitudinal axis L, and at a high momentum, in order to form a recirculation flow over a wide area. For this purpose, the air/fuel supply arrangements 50 comprise the air channels 504, which are arranged in the form of an annulus, for forming the nozzle ring. The air channels 504 in each case lead, via a first outlet 512, into the combustion space 24, and are oriented in the longitudinal direction, along a central axis M extending in parallel with the longitudinal axis L. The air channels 504 are in flow connection, via the upstream ends thereof, with the air distribution space 30, which in the present case forms an air plenum and from which said channels are supplied with air.

As is more clearly visible from Fig. 2A, the air channels 504 each comprise a first portion 520, arranged upstream, and a second portion 522, arranged downstream, which second portion is reduced in cross section compared with the first portion 520 , for accelerating the flow. The portions 520, 522 are in each case designed in particular cylindrically, a different cross-sectional shape also being conceivable. The reduction in — cross section between the two portions 520, 522 can be designed conically or continuously, for example as a cross-sectional jump.

The air/fuel supply arrangements 50 comprise fuel channels 502, which protrude into the air channels 504 in each case. The fuel channels 502 are in each case delimited by a wall 501 and are arranged on the central axis M, in the longitudinal direction. The fuel channels 502 form a flow connection of the distribution region 38 for fuel, these extending, proceeding herefrom, through the insulating material 33 and the air distribution space 30, and end portions 503 thereof being arranged in each case inside the air channels 504 and coaxially thereto. Fuel openings 510 of the fuel channels 502 open into the air channels 504 for coaxially adding fuel into the air. The fuel openings 510 are positioned axially, directly at the start, within, or downstream of, the reduction in cross section.

The fuel openings 510 each form first supply openings for supply fuel into the air flow. Upstream of the fuel opening 510, the flow paths of the fresh gas components extend — in separate flow portions, at least in part. Downstream of the fuel openings 510, mixing spaces 508 are formed in the air channels 504, in which mixing spaces the flow paths of air and fuel are combined, i.e. the entire fuel flow is introduced into the airflow in the mixing spaces. The mixing spaces 508 serve for at least partial pre-mixing of fuel and air, upstream of the supply thereof into the combustion chamber 6 or the combustion space 24.

According to a core concept of the invention, the air/fuel supply arrangements 50 comprise, in addition to the fuel openings 510, as first supply openings, further flow portions comprising further supply openings. In this case, the further flow portions are formed for example by a drawing of, e.g. four, bypass channels 526. The bypass channels 526 are introduced into the walls 501 of the fuel channels 502 for example rotationally symmetrically all around the central axis, and axially at the same height. They have, for example, a circular cross section. - The bypass openings 528 are arranged inside the air channel 504, axially upstream of an outflow portion 516 of the end portion 503 of the fuel channel 502. The end portion 503 extends between the downstream edges of the bypass openings 528 and the fuel openings 510. The length of the outflow portion 516 is selected such that inlet effects in the case of inflow of one fresh gas component, in this variant in particular air, into the other have at least largely subsided by the time the fuel opening 510 is reached. For example, there is no more recirculation flow present at the fuel opening 510.

Furthermore, the bypass openings 528 (having the edges positioned upstream) are arranged downstream of inflow portions 514, within the air channels 504. The length of the inflow portions 514 is such that the inlet effect of the airflow in the case of inflow into the air channels 504, in particular e.g. recirculation regions at the inlet opening, have subsided by the time the bypass channels 526 are reached. Furthermore, it is thus possible to reduce the likelihood of fuel entering the air distribution region 30 in the event of a brief flow reversal in the case of a transient maneuver. For this purpose, the air channels 504 are optionally of a greater length than recirculation-stabilized jet flame burners known from the prior art.

In the first variant shown in Fig. 1, which is shown in more detail in Figs. 2A to 2C, the air/fuel supply arrangements 50 are designed proceeding from a low-calorific design — point (a design operating point for operation using a low-calorific design fuel, for example a synthesis gas having a calorific value of 5 MJ/ kg). In this case, the flow cross sections, or in this case diameter d3, of the fuel openings 510, and the flow cross sections or diameter d of the fuel channels 502, correspond to one another.

Figs. 3A to 3C show a second variant, in which the air/fuel supply arrangements 50 are designed proceeding from a high-calorific design point (a design operating point for operation using a high-calorific design fuel, for example natural gas having a calorific value of just under 50 MJ/kg). In this case, the flow cross section at the fuel opening 510, or in this case the diameter d3, is reduced compared with the flow cross section or the diameter da of the fuel channel 502, in order to accelerate the fuel flow to a desired velocity at the fuel opening 510.

In both cases, the diameter ds is designed in such a way that the velocities of the (low-calorific or high-calorific design) fuel at the fuel opening 510 is similar to the velocity of the fresh gas mixture at the outlet 512 into the combustion space 24 (for example between +/- 50%, in particular between +/- 20%). Typical velocities for a recirculation- stabilized jet flame burner, for example between 60 m/s and 180 m/s) are present at the outlet 512. The similar entry velocities prevent flow separations and associated fuel fluctuations at the fuel opening 510, and promote a stable combustion process.

In this case, the bypass channels 526 extend, by way of example, radially-axially at an angle a with respect to the central axis M. In the first embodiment (Figs. 2A to 20), the angle ais for example between 15° and 45° (an open in the upstream direction). In the second embodiment (Figs. 3A to 3C), the angle a is for example between 135° and 165° (a open in the upstream direction). These orientations in each case promote a desired flow direction between the air flow path and the fuel flow path, which will be explained below. - [0072] The angle a and the total flow cross sections of the bypass channels 526 and/or the bypass openings 528 (i.e. the sum of the flow cross sections of the fuel channels 526 or fuel openings 528) are designed with respect to the high-calorific design point in the first embodiment, and with respect to the low-calorific design point in the second embodiment.

The design is such that the velocities at the fuel openings 510 in the high-calorific or low-calorific design point are adjusted to the velocities in the low-calorific and high-calorific design point, respectively, ie. the velocities are similar. For example, the “low-calorific/high-calorific” velocity ratio at the fuel openings 510 is smaller by a factor of 2, preferably smaller by a factor of 1.5.

In the first variant, the flow guidance during operation is indicated by arrows in

figs 2B and 2C. Fig. 2B shows the flow guidance in the low-calorific design point, having a large fuel mass or volume flow. Air and fuel are firstly guided to the bypass opening through the air channel 504 and the fuel channel 502, respectively, in separate flow portions. The pressure ratios in the air channel 504 and the fuel channel 502 are similar, at the low-calorific design point, such that the portion of air flowing through the bypass opening 528 is (substantially) zero. Therefore no, or at most a low, driving force results, which force brings about a flow through the bypass openings 528. Consequently, the air flows (at least largely) through the air channel 504, and the fuel flows through the fuel channel 502 , in a substantially separated manner, as far as the fuel opening 510, where the fresh gas components are combined.

In the high-calorific design point (Fig. 2C), having the substantially smaller fuel volume flow, a smaller pressure loss results in the fuel channel 502 than in the surrounding air channel 504. The resulting pressure difference means that a portion of the air already flows through the bypass channel 526, comprising the bypass openings 528, and into the fuel channel 502, upstream of the fuel opening 510. This increases the volume flow inside the fuel channel 502, between the bypass openings 528 and the fuel opening 510. The — portion of air results from the corresponding design of the bypass channels 526 and the bypass openings 528, such that the desired velocity is provided at the fuel opening 510. In this case, diameters di of the bypass channels 526 can be e.g. between 10% and 40% of the diameter d> of the fuel channel 502. This increases the stability of the combustion, by significantly preventing fuel fluctuations at the fuel opening. Without the design comprising the bypass channels 526, for example velocity differences by a factor of 5 would result.

In the second variant, the flow guidance during operation is indicated by arrows in

figs 3B and 3C. Fig. 3B shows the flow guidance in the low-calorific design point, having —a large fuel volume flow. Air and fuel are firstly guided to the bypass opening 528 through the air channel 504 and the fuel channel 502, respectively. As a result of the high fuel mass or volume flow, a higher pressure drop occurs at the fuel opening 510. Accordingly, an increased pressure results upstream in the fuel channel 502, which pressure leads to an increased pressure difference between the fuel channel 502 and the surrounding air channel — 504 The pressure difference means that, for pressure compensation, a portion of fuel flows through the bypass channel 526, comprising the bypass openings 528, and into the air channel 504. Thus, downstream of the bypass openings 528 one portion of the fuel flow flows, together the air flow, as far as the location of the fuel opening 510, and the other portion continues to flow separately via the fuel channel 502 as far as the fuel opening 510.

The bypass channels 526 comprising the bypass openings 528 are designed, in particular with respect to their angle a and the flow cross sections, such that a pressure difference is brought about, by means of which the fuel flow is separated in portions such that the — Velocity at the fuel opening 510 is similar (for example by a factor of 2 or less, preferably by a factor of 1.3 or less) to said velocity at the high-calorific design point. In this case, diameters di of the bypass channels 526 can be e.g. between 10% and 50% of the diameter d> of the fuel channel 502.

In the high-calorific design point, having the comparatively small fuel volume flow, the pressure ratios between the fuel channel 502 and the air channel 504 are similar to one another. Therefore no, or at most a low, driving force for the flow through the bypass channel 526, comprising the bypass opening 528, results. - The fuel compositions in the low-calorific and in the high-calorific design points preferably represent extremes between which the fuel compositions can range during operation. In the case of a change in the fuel composition and the calorific value or Wobbe index of the fuel, between these extremes, during operation, the pressure ratios within the air/fuel supply arrangements 50 are adjusted accordingly, such that the portion of the fresh gas, in each case, which flows into the flow path of the other fresh gas, is of such a size that the desired equalization of the velocities occurs.

The second air/fuel supply arrangement 60 (cf. Fig. 1 and Figs. 5, 6A, 6B) is designed to supply the fresh gas components air and fuel to the second combustion space 26 in a swirling flow, i.e. having a tangential directional component. For this purpose, the air/fuel supply arrangement 60 comprises a mixing space 608 which is arranged upstream of the combustion space 26, on the bottom in the inner wall, such that an outlet 612 thereof opens, downstream, into the combustion space 26. The mixing space 608 is arranged centrally, on the longitudinal axis L, and is symmetrical with respect to said axis, in particular cylindrical. As Figs. 6A and B show in more detail, the mixing space 608 is delimited on the bottom by a bottom wall 626, which in this case is oriented, by way of example, perpendicularly to the longitudinal axis L. The mixing space 608 is delimited on the periphery by a wall 609. The mixing space 608 serves to pre-mix the fresh gas components, at least in part.

As shown in more detail in Figs. 4 and 5, a diffused of air channels 604 comprising air openings 610, of which there are three here, by way of example, open into the mixing space 608 on the periphery, in the wall 609. The air channels 604 form a flow connection between the air distribution space 30 and the mixing space 608, and form separate flow — portions of the air flow path, in this case, by way of example, for a pilot stage. The air channels 604 have for example a circular cross section. The air channels 604 extend, by way of example, in an axially constant manner, in a plane perpendicular to the longitudinal axis L, and are oriented tangentially with respect to the cylindrical mixing space 608, in order to impress a tangential directional component on the emerging air flow, for generating the swirling flow. The orientation could additionally comprise a radial directional component.

[0080] Preferably, in a manner alternating with the air channels 604 in each case, the same number of fuel channels 602, in the present case, by way of example, three, open by way of fuel openings 614, on the periphery, into the mixing space 608. The alternating arrangement allows for more uniform mixing of the fuel into the air. The fuel channels 602 have, for example, a circular cross section, and separate flow portions of the flow paths for the fuel. The openings of the air and fuel channels are arranged rotationally symmetrically with respect to the longitudinal axis L, in this case, by way of example, offset relative to one another by 60°. In each case an end portion 601 of the fuel channels 602 extends in an axially constant manner, in a plane perpendicular to the longitudinal axis L, and tangentially, optionally having an additional radial directional component, to the mixing space 608. — [0081] The end portions 601 of the fuel channels 602 are preferably aligned with the air channels 604, in a tangential-radial manner. The fuel can thus also drive the rotational movement of the swirling flow. The fuel channels 602 are designed such that, in the low-calorific design point having the higher mass and volume flows, the rotational movement of the swirling flow is driven together therewith. In this case, the fresh gas components in each case have similar orders of magnitude in the case of the inflow velocities into the mixing space 608, for example the fuel velocity being 10% and 120%, in particular between 15% and 80%, of the air velocity. The air velocity can for example be between 50 m/s and 120 m/s, and is such that a flame-stabilizing swirling flow is achieved.

The fuel opening 614 and the air openings 610 are arranged axially offset from one another, the axial lower edges of the fuel openings 614 being arranged further downstream than the axial lower edges of the air openings 610 air openings 610 can for example adjoin the bottom wall 626 in a manner flush with the bottom. Thus, — the generally substantially larger air flow can counteract an undesired stabilization of a flame at the fuel opening 610.

Upstream of the end portions 601, the fuel channels 602 comprise axial portions 605, which proceed from the distribution region 40. The distribution region 40 is arranged centrally on the longitudinal axis L, and adjoins the rear of the bottom wall 626. The radial extent of the distribution region 40 is larger than that of the mixing space 608, such that the fuel flow, proceeding from the distribution region 40, can be easily supplied to the mixing space 608 via the axial portions 605 and the downstream end portions 601. The distribution region 40 is fed by the second fuel supply 36, arranged centrally, on the longitudinal axis L. The central arrangement of the fuel supply 36 and of the distribution region 40, having the arrangement thereof adjacently to the rear of the bottom wall 626, therefore allows for cooling of the bottom wall 626 by means of the supplied fuel flow, which, during supply, strikes the rear of the bottom wall 626 and cools this in the manner of impact cooling. The fuel channels 602, arranged uniformly around the mixing space 608 and comprising the axial portions 605 and end portions 601, also contribute to the cooling of the mixing space 608. The temperature load in the burner head 4 is reduced as a result. Temperature-sensitive components, such as an ignition device or bearing points, can be arranged in these regions. This has a positive influence on the service life of the individual components of the burner system 1.

The fuel openings 614 form a group of first supply openings, the fresh gas components fuel and air being combined in the mixing space 608. According to a core concept of the invention, further flow portions, formed by second fuel channels 603, are provided, which in each case open into the mixing space 608 of one group via further supply openings, formed by second fuel openings 616. The second fuel channels 603 are oriented axially with respect to the longitudinal axis L, it being possible for said channels to also have a radial component. The second fuel openings 616 are arranged in the mixing space

608, in particular in the bottom wall 626, at a location B (in this case region), at which there is a lower pressure at a high-calorific design point than at a location A (in this case region) of the first fuel openings 614. Such a location is positioned for example flush with the side of the bottom wall 626 facing towards the mixing space 608, in a manner radially offset with respect to the longitudinal axisL. An arrangement of this kind results, during operation at the high-calorific design point, in a pressure difference, via which the fuel preferably flows via the second fuel channels 603 and the second fuel openings 616 into the mixing space 608. The flow cross sections or the total flow cross section of the second fuel channels 603 are designed such that the velocities at the second fuel openings 616 are for example — between 30% and 80% of the velocity of the air flow. This brings about good mixing-in of the fuel into the swirled air flow. In the high-calorific design point, the fuel flow via the second fuel channels 603 is (virtually) 100%, and that via the first fuel channels 602 is (virtually) 0%. - [0086] In Figs. 6A and 6B, the flow guidance during operation is indicated by arrows.

Fig. 6A shows the operation in the low-calorific design point, having a large fuel mass flow.

In this case, the fuel flows through the distribution region 40. The flow cross sections of the second fuel channels 603 or the second fuel openings 616 or the total flow cross section (sum of the flow cross sections) is selected such that, in the case of the low-calorific design point, a high pressure loss within the second fuel channels 603 results. The pressure loss brought about by the design is so great that a portion, for example between 90% and 30%, of the fuel opening flows into the mixing space 608 via the first fuel channels 602, the fuel at the first fuel openings 614 having a velocity of e.g. 10% to 30% of the air flow at the air openings 610. Thus, the rotation of the swirling flow is driven along by the high fuel mass — flows. The other portion of the fuel, e.g. 10% to 70%, flows via the second fuel channels 603.

At the high-calorific design point, having the small fuel mass flow, the pressure difference over the second fuel channels 603, together with a blocking effect of the air flow at the first fuel openings 614, results in the fuel mass flow preferably, e.g (virtually) completely, flowing via the second fuel channels 603 having the second fuel openings 616.

The swirling flow of the air carries along and accelerates the fuel flowing into the mixing space 608.

Both at the low-calorific and at the high-calorific design point, the air velocities are such that a flame stabilization is achieved by the swirling flow. The portion of the fuel flow via the second fuel channels 603 varies for example between 10% to 70% and (virtually) 100%, between the low-calorific and the high-calorific design point. In this way, a stable, — pressure-loss-optimized (and thus efficient) operation can be achieved using low-, medium- and high-calorific fuels, while the geometry remains the same.

The design according to the invention of the burner system 1 and the method according to the invention makes it possible for the burner system 1 to be operated in a - stable and reliable manner both using low-calorific and also using high-calorific fuels, and variants therebetween. Since the adjusted flow through the air/fuel supply arrangements is set on account of the changing pressure ratios having the changing calorific value or Wobbe index, without changing the (burner head) geometry, therefore no adjustment or control via a control means is reguired.

Claims (17)

Patent Claims 1. A burner system (1) for generating hot gas in a gas turbine plant having a combustion chamber (6) comprising a combustion space (24, 26) aligned along a longitudinal axis (L) and having a burner head (4) with at least one oxidizer/fuel supply arrangement (50 ) for supplying oxidizer and fuel as components of new gas to the combustion chamber (6), which comprises - one flow path in each case for fuel and oxidizer to supply them to the combustion chamber (24, 26), where the upstream flow paths of the mixing chamber (508) each have separate flow sections to control the components of the new gas separately and the flow paths are connected in the mixing space (508) and - at least one first supply opening for supplying fuel to the mixing space (508), where the oxidizer/fuel supply arrangement (50) comprises at least one additional flow part with an additional supply opening through which part of one new gas component enters the combustion space (24; 26) for feeding can be fed into the flow part with another new gas component, where the additional flow part is arranged and shaped in such a way that in the situation, if the geometry has not been changed, the part of the new gas component flowing through the additional flow part can be changed by the calorific value of the fuel as a result of the change in the pressure ratio, so that the velocities of the first supply opening and/or at the additional feed opening, the low-temperature design point and the high-temperature design point differ by a factor of no more than 2, especially a factor of no more than 1.5, preferably a factor of no more than 1.2, where - — low-temperature — design point — corresponds to — — design — operating point with a low-temperature design fuel whose calorific value per mass is about 5 MJ/kg and the high-temperature design point corresponds to the design operating point with a high-temperature design fuel whose mass-specific calorific value does not exceed 50 MJ/kg, - the heat outputs of the two design points correspond to each other and - the additional feed opening is shaped with at least one bypass opening (528), where the bypass opening (528) is shaped on its wall ( 501) upstream of the fuel channel (502) relative to the fuel opening (510) and where the additional flow part forms a flow connection between the oxidizer and the fuel flow paths. 2. A burner system (1) for generating hot gas in a gas turbine plant having a combustion chamber (6) comprising a combustion space (24, 26) aligned along a longitudinal axis (L) and having a burner head (4) with at least one oxidizer/fuel supply arrangement (60 ) for supplying oxidizer and fuel as components of new gas — to the combustion chamber (6), which comprises - one flow path in each case for fuel and oxidizer to supply them to the combustion chamber (24, 26), where the upstream flow paths of the mixing chamber (608) each have separate flow sections to control the components of the new gas separately and the flow paths are connected in the mixing space (608) and - at least one first supply opening for supplying fuel to the mixing space (608), where the first supply opening is shaped by the first combustion opening (614), where the oxidizer/fuel supply arrangement (60) comprises at least one additional flow part with an additional supply opening, which through one new gas component for feeding into the combustion chamber (24, 26) can be fed into the flow part with another new gas component, where the additional flow part is arranged and shaped in such a way that in the situation, if the geometry has not been changed, the part of the new gas component flowing through the additional flow part can be changed by the heat value of the fuel as a result of a change in the pressure ratio, so that the velocities at the first inlet and/or additional inlet differ from each other between the low-temperature design point and the high-temperature design point by a factor of no more than 2, especially a factor of no more than 1.5, preferably a factor of no more than 1.2, where - — low-temperature — design point — corresponds to — design — operating point with a low-temperature design fuel whose mass-specific calorific value is approximately 5 MJ/kg and the high-temperature design point corresponds to the design operating point with a high-temperature design fuel whose mass-specific calorific value does not exceed 50 MJ/kg, - the heat outputs of the two design points correspond to each other, - the mixing space (608) is arranged centrally along the longitudinal axis (L) and is symmetrical with respect to said axis and is limited to the bottom wall (626) at the bottom, which is preferably oriented perpendicular to the longitudinal axis (L) and peripherally on the wall (609) and opens downstream to the combustion chamber (26) with an outlet (612) where the new gas the components can be fed into the mixing space (608) in such a way that a tangential orientation component is generated in the rotating flow and - an additional feed opening is shaped with a second fuel opening (616) into the mixing space (608), where the additional flow part comprises a second fuel channel (603) which is oriented with an axial orientation component with respect to the longitudinal axis (L) . 3. Burner system (1) according to claim 1, characterized in that the oxidizer/fuel supply arrangement (50) has an oxidizer channel (504) with an outlet opening (512) for opening into the combustion chamber (6), the outlet flow part (516) of the oxidizer channel (504) is aligned along the central axis (M) which extends substantially axially parallel to the longitudinal axis (L). 4. Burner system (1) according to claim 3, — characterized in that the oxidizer/fuel supply arrangement (50) has a fuel channel (502) bounded by a wall (501), whose channel is shaped to extend parallel, in particular coaxially, with the oxidizer channel (504), with at least one end part (503) in the oxidizer channel (504) and whose fuel opening (510) opens inside the oxidizer channel (504) or its discharge opening (512), the fuel opening (510) forms the first supply opening. 5. Burner system (1) according to claim 4, characterized in that the fuel opening (510) has a flow cross-section, in particular a diameter (d3), which has been reduced compared to a flow cross-section, which has in particular the diameter (d2) of the fuel channel (502) extending upstream or from , that the fuel opening (510) has a cross-section of the flow, in particular a diameter (d3), which corresponds to a cross-section of the flow, in particular a diameter (d2) of the fuel channel (502) extending upstream. 6. Burner system (1) according to any one of claims 1 or 3-5, characterized in that the flow cross-section of the fuel opening (510) is shaped so that at the low-temperature design point — or — at the high-temperature — design point — the speed at the fuel opening (510) is + /- 50%, preferably +/- 20% of the rate of new gas mixing in the outlet (512) of the combustion chamber (24), the part flowing through the bypass (528) is equal to zero. 7. Burner system (1) according to any one of the preceding claims, characterized in that there are several additional flow parts which are particularly symmetrical with respect to each other, — for example arranged rotationally symmetrically around the central axis (M) and axially at the same height. 8. Burner system (1) according to any one of claims 1 or 3-7, characterized in that the bypass opening (528) is arranged axially inside the oxidizer channel (504) downstream of the inflow part (514) of the oxidizer channel (504), which preferably has such an axial length, that the inlet affects the oxidizer flow, if there is an inflow into the oxidizer channel (504), in particular the local flow differences are significantly reduced at the bypass opening (528), and/or that the bypass opening (528) is arranged axially inside the oxidizer channel (504) in the outflow part of the end part (503) ( 516) relative to the upstream, which preferably has such an axial length that the inlet is affected in the case where one component of the new gas flowing into the other is significantly attenuated at the fuel opening (510). 9. Burner system (1) according to any one of claims 1 or 3-8, characterized in that the additional flow part comprises a bypass channel (526) in the wall (501), such a channel protrudes radially-axially at an angle (a) with respect to the central axis (M). 10. Burner system (1) according to claim 9, characterized in that the angle (a) is 0-90°, especially 10-60*, is for example 15-45° or in that the angle (a) is 90-180°, especially 110-170°, is for example 135-165°. 11. Burner system (1) according to any one of claims 3-10, characterized in that the oxidizer channel (504) comprises a first part (520) in its axial path and a second part (522) downstream of the first part (520), the reduction in the cross-section is arranged by two between the part (520, 522) and that the fuel opening (510) is arranged axially within or downstream of the cross-sectional reduction. 12. Burner system (1) according to claim 2 or claim 7, characterized in that the oxidizer/fuel supply arrangement (60) has at least one oxidizer channel (604) that opens into the mixing space (608) at the edge and is oriented with a tangential — orientation component — relative to — the longitudinal axis = (L), the oxidizer channel (604) is connected to a separate flow part of the oxidizer and/or from the fact that the fuel distribution area (40) is connected to the oxidizer/fuel supply arrangement (50, 60), the area of which is arranged especially symmetrically in relation to, for example centrally, the longitudinal axis ( L) and is next to the back of the bottom wall (626). 13. Burner system (1) according to any one of claims 2, 7 or 12, characterized in that the first supply opening is shaped by at least one first fuel opening — (614), which opens into the mixing space (608) on the edge and which shapes the downstream end of the first fuel channel (602), the end part (601) of the fuel channel (602) extends with a tangential orientation component relative to the longitudinal axis. 14. Burner system (1) according to claim 13, — characterized in that the oxidizer opening (610) of the oxidizer channel (604) and the first fuel opening (614) are arranged axially apart from each other, the oxidizer opening (610) the axial lower edge is arranged upstream of the axial lower edge of the fuel opening (614) and/or that the cross-section of the first — the entire — flow of the fuel opening (614) is shaped in such a way that the fuel inflow rate into the mixing space (608) at the low-temperature design point is 10-120%, especially 15- 80% of the oxidizer inflow rate at the oxidizer opening (610). 15. Burner system (1) according to any one of claims 2, 7 or 12-14, characterized in that the second fuel opening (616) is arranged in the mixing space (608) at point (B) with a lower pressure at the high-temperature design point than the first fuel opening (614) in (A) and/or that the second fuel channel (603) forms a flow connection between the distribution area (40) and the mixing space (608) and extends through the bottom wall (626), the second fuel opening (616) is positioned in particular so that it is axially level with the surface of the bottom wall (626) on the side of the mixing chamber. 16. Burner system (1) according to any one of claims 2, 7 or 12-15, characterized in that the cross-section/sections of the entire flow of the additional flow part/parts are designed so that at the high temperature design point the part, at least 70%, preferably at least 90%, for example 100%, of the fuel flows through the second fuel channel (603) and/or, at the low temperature design point, a part, at least 30%, preferably at least 70%, for example at least 90%, of the fuel flows through the first fuel channel (602). 17. A method for — hot — gas — generation — at any = gas turbine plant equipped with a burner system (1) according to the previous claim, where oxidizer and fuel are fed into the combustion chamber (24, 26) of the combustion chamber (6) as components of new gas at the burner head (4) at least one oxidizer/ through the fuel supply arrangement (50, 60), the components of the new gas each flow through a flow path having separate flow sections in the oxidizer/fuel supply arrangement (50, 60) to the mixing space (508, 608) where the flow paths of the components of the new gas are combined, the fuel flows past the first supply port , where it opens into the mixing space (508, 608), characterized in that — one component of the new gas flows in the burner head (4), in particular in the oxidizer/fuel supply arrangement (50, 60) and it can be divided into at least two parts, one part in the oxidizer/fuel supply arrangement (50, 60) flows through at least one additional flow section having an additional feed opening and, in the case of a fixed geometry, the portion of the new gas component flowing through the additional flow section changes the calorific value of the fuel — as a result of a changing pressure ratio, so that the velocities in the first fuel port and/or additional supply port differ from each other between the low-temperature design point and the high-temperature design point by a factor of no more than 2, especially a factor of no more than 1.5, preferably a factor of no more than 1.2.