EP3584501B1 - Burner system and method for generating hot gas in a gas turbine plant - Google Patents

Description

The invention relates to a burner system for generating hot gas in a gas turbine system, with a combustion chamber that includes a combustion chamber aligned along a longitudinal axis, and with a burner head with at least one oxidizer/fuel supply arrangement for supplying oxidizer and fuel as fresh gas components into the combustion chamber one flow path each for fuel and oxidizer for feeding them into the combustion chamber, with the flow paths upstream of a mixing chamber each having separate flow sections for separate routing of the fresh gas components, and the flow paths in the mixing chamber are combined, and at least one first feed opening for feeding fuel into the mixing room. The invention also relates to a corresponding method for generating hot gas in a gas turbine system.

Such a burner system is, for example, from WO 2014/027005 A2 out.

In recent times, interest has been growing in addition to conventional fuels such as e.g. B. natural gas, to use other fuels with different compositions energetically. Such fuels provide z. B. synthesis gas from biomass gasification, sewage gas, landfill gas, biogas, mine gas or associated gas. The energetic conversion of the fuels can, for example, in gas turbine plants, in particular in micro gas turbine systems, where the fuels are converted into a hot gas with hot exhaust gas in a combustion process. To do this, the fuels must be burned reliably, efficiently and with low emissions.

The different fuels can differ significantly in their composition. So z. B. Natural gas has a high proportion of methane as a component, while a typical synthesis gas usually contains a high proportion of inert gas (especially carbon dioxide and nitrogen) in addition to hydrogen and possibly other combustible components (e.g. carbon monoxide, methane). The fuels therefore have differences in their combustion properties, e.g. B. flame speed and ignition delay time, and in their calorific values or their Wobbe indices (as a parameter for assessing the interchangeability of fuel gases). So e.g. B. natural gas, with a mass-specific calorific value of just under 50 MJ / kg, to be assigned to the high-calorific fuels, whereas a typical synthesis gas as a low-calorific fuel, for example, can have a mass-specific calorific value of about 5 MJ / kg or less. Medium-calorific fuels have calorific values between these extremes. Thus, when using such a low-calorific synthesis gas, compared to—high-calorific—natural gas, an approximately tenfold greater fuel mass flow is necessary to achieve a corresponding performance. These different properties make it difficult to use different fuel qualities in a single burner system.

A known procedure for using both high-calorific and low-calorific fuels in a single burner system is to introduce them separately. The different fuels are introduced via separate feeds, each of which is designed for the specific properties of the fuel. Another approach is to replace and/or adapt the Fuel nozzles or channels with a change in geometry. However, this is expensive and usually does not allow any adjustment during ongoing burner operation.

the U.S. 4,967,561A shows a burner system in which either a liquid or gaseous fuel can be introduced into a combustion chamber for combustion. For this purpose, the burner system has a large number of tubular bodies, within which, for premixing, a liquid or gaseous fuel can be added to the combustion air for premixing via separate nozzles that differ when different fuels are added.

Burner systems, in particular for operation with medium or low-calorific fuels, are in the U.S. 6,684,640 B2 , the DE 44 09 918 A1 , the EP 1 800 062 B1 , the EP 1 892 469 A1 and the EP 0 908 671 A1 disclosed.

A burner system based on the principle of a recirculation-stabilized jet flame burner is the EP 1 995 515 A1 removable.

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

the U.S. 2004/068973 A1 shows a burner with several oxidant-carrying channels of different burner stages and a fuel channel. In order to adapt the amounts of fuel within the oxidant-carrying channels at different load ranges, the burner has a so-called "fluid control construction" which comprises an open area and a feed area. In this case, the fuel flow is distributed differently to the different burner stages depending on a critical volume flow in order to comply with the upper flammability limit.

the U.S. 2010/077759 A1 discloses a gas turbine combustor having a primary fuel nozzle for a primary combustor and a secondary fuel nozzle for a secondary combustor. The secondary fuel nozzle has a premixing section, through which fuel can be added to the combustion chamber both through radial gas feeds and through a pilot bore opening downstream thereof. A design for operation with fuels of different calorific values is not specified.

In the JP 3 976464 B2 discloses a combustor having a fluid mixer including a plurality of feed ports. A design for operation with fuels of different calorific values is not specified.

the EP 1 255 080 A1 deals with a catalytic burner in training as a swirl burner. A design for operation with fuels of different calorific values is not specified.

the U.S. 2010/139238 A1 discloses a burner for operation with a low-calorific fuel which is also operable with a high-calorific fuel. The fuels with different calorific values are introduced into the combustion chamber via different fuel feeds.

The object of the invention is to provide a burner system and a method for generating hot gas that enables reliable, low-emission and efficient operation with both high-calorific and low-calorific fuels at comparatively little expense.

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 section with a further supply opening, via which a proportion of one of the fresh gas components can be fed into a flow section with the other fresh gas component for supply into the combustion chamber. the further flow section being arranged and designed in such a way that the proportion of the fresh 4 gas component which flows over the further flow section can be changed with the calorific value of the fuel due to a changing pressure ratio while the geometry remains unchanged.

The share refers z. B. on the total, flowing through the oxidizer / fuel supply arrangement mass or volumetric flow of the corresponding fresh gas. The further flow section is arranged in particular in such a way that the corresponding fresh gas component flow is divided into at least two parts within the burner head, i. H. the further flow section branches off within the burner head from the separate flow section(s).

The flow section with the other fresh gas component can be, for example, one of the flow sections of fuel or oxidizer upstream of the mixing space. For example, the flow paths of the fresh gas components are routed separately upstream of the further feed opening and are partially combined downstream of the further feed opening/initially in a common and a (further separate) flow section before they turn downstream of the first feed opening are completely brought together in the mixing chamber as a common flow section. The merging can thus take place in stages one after the other, with the further feed opening being arranged upstream of the first feed opening. Particularly alternatively, the flow section with the other fresh gas component can be formed by the mixing chamber, in which case in particular a proportion of the fuel can flow via the separate flow section with the first feed opening and the other proportion can flow into the mixing chamber via the further flow section (which can be passed in parallel) and the further feed opening . In this case, the separate flow section with the first feed opening and the further flow section open into the mixing chamber so that they can be passed in parallel. Both alternatives can exist in the same burner system.

In a design variant with (at least partial) premixing of the fresh gases before introduction into the combustion chamber, the mixing chamber is part of the burner head, in particular the oxidizer/fuel supply arrangement, forming a common flow section. In a design variant that is also possible with a non-premixed introduction into the combustion chamber, the mixing chamber corresponds to a region of the combustion chamber.

The first and further feed openings can also be groups of first and further feed openings (and/or flow sections associated with them) which, for. B. in different (flow) areas are arranged, the groups z. B. are each designed according to corresponding design criteria and / or fulfill a corresponding function. In contrast, the first and the other / n feed opening / s differ from each other z. B. by their design criteria and / or function.

The arrangement and / or design of the other flow section is such that the proportion when introducing fuel with a different calorific value (or a different Wobbe index) due to changing aerodynamic Conditions, especially the pressure conditions, changes. The geometry remains unchanged, in particular the flow cross sections of the flow sections remain constant. There is no need to regulate the volume flow by means of adjusting devices, in particular valves. In this way, different fuels can advantageously be supplied via the same oxidizer/fuel supply arrangements. This advantageously allows the use of changing fuels and/or mixed operation, e.g. B. with a continuous change in the fuel composition, with little effort and during operation.

In a method of interpretation z. B. proceed as follows to arrive at the burner system according to the invention: Based on a known generic burner system, one or more pairings of locations is/are located within the separate flow sections of oxidizer and fuel at which the pressure difference and/or the pressure ratio changes between a high-calorific and a low-calorific design point to the flow section with the respective other fresh gas component (fuel or oxidizer). This can e.g. B. via a pressure determination using computer-aided flow simulation and / or done experimentally, with z. B. the mass or volume flows can be adjusted according to the design operating points. Connecting this pairing of locations to one another, one or more further flow section(s) with a further feed opening is/are now arranged. The (respective) further flow section is designed, in particular arranged and/or formed (e.g. with a corresponding flow cross section) according to the desired division or proportions. In doing so, e.g. B. (initially) an approximate pressure drop calculation and/or (subsequently) an iterative approach to a design goal, e.g. B. by means of computer-aided flow simulation and / or experimentally. The design goal can be, for example, maintaining a certain speed range between the different design points.

In a preferred variant of the design, the design goal is that the proportion can be changed in such a way that the speeds at the first and/or at the further feed opening between a low-calorific design point and a high-calorific design point by a maximum of a factor of 2 (speed with low-calorific to speed with high-calorific Fuel), in particular by a maximum of a factor of 1.5, preferably a maximum of a factor of 1.2, deviate from one another, ie the speeds in the different design points are similar to one another. The “low-calorific design point” corresponds to a design operating point with a low-calorific design fuel, for example a synthesis gas, with a mass-specific calorific value of approx. 5 MJ/kg. The “high-calorific design point” corresponds to a design operating point with a high-calorific design fuel, for example natural gas, with a mass-specific calorific value of just under 50 MJ/kg. The thermal outputs of the two design points correspond to each other, although they are specified on the machine side. In a micro gas turbine arrangement in which the burner system according to the invention z. B. can be used advantageously, the thermal power z. up to 1 MW or 500 kW, e.g. B. be around 300 kW. The air ratio or the combustion air ratio corresponds, for example, to that of a known, generic burner system and can, for. B. be between 1.4 and 3.4. The fuel compositions in the low-calorific and high-calorie design point preferably represent extremes with regard to the calorific value, between which the calorific values of the fuel compositions move during operation. The similar speeds (as defined above) can be achieved by the design and/or arrangement of the further flow section with the further feed opening. The design is preferably carried out, as is common nowadays, using computer-aided flow simulation. What is achieved in this way is that, in particular, those speeds which decisively influence the combustion process in the combustion chamber system are similar to one another with different fuels (at least to the extent mentioned above). stay. In this way, certain operating characteristics, for example (at least in part or in certain areas) the mixing of fuel into the oxidizer, can be matched in both design points. This contributes to a stable, low-emission and efficient combustion process with both low, medium and high-calorific fuels.

In a preferred embodiment variant of the burner system according to claim 1, the oxidizer/fuel supply arrangement has an oxidizer duct with an outlet to the mouth into the combustion chamber, the oxidizer duct being aligned with an outflow section comprising the outlet along a central axis M, which is essentially axial parallel to the longitudinal axis. The oxidizer channel forms an oxidizer flow path that guides the oxidizer separately in an upstream portion. The upstream end of the oxidizer channel can in particular be in flow communication with an oxidizer distribution space of the burner head, so that the oxidizer channel forms a flow connection for the oxidizer between the oxidizer distribution space and the combustion chamber. The oxidizer channel can in particular be designed in the manner of a nozzle. Due to the axial arrangement, the oxidizer can be introduced into the combustion chamber with a high axial impulse, so that a pronounced recirculation zone is formed in the combustion chamber, which stabilizes the combustion, as is usual with a recirculation-stabilized jet flame burner (also known as "FLOX burner") . Such a design allows 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 and which has at least one end section in the oxidizer channel running parallel, in particular coaxially, to the oxidizer channel and which has a fuel opening inside the oxidizer channel or opens out at its outlet, the fuel orifice forming the first feed opening. In the fuel channel, upstream of the fuel orifice (and possibly upstream of the other Feed opening) formed the separate portion of the fuel flow path. The fuel channel can in particular form a flow connection between a fuel distribution area and the mixing space. By designing the fuel channel with the fuel orifice in this way, the fuel can be added coaxially into the air flow, which supports symmetrical, uniform fuel mixing in the oxidizer and thus a uniform, stable combustion process with low emissions.

In a variant embodiment of the burner system according to claim 1, the fuel orifice has a flow cross section, in particular with a diameter d ₃ , which is reduced compared to the flow cross section, in particular with a diameter d ₂ , of the fuel channel running upstream. The flow cross-section of the fuel orifice is preferably designed in such a way that a speed similar to the speed of the fresh gases at the exit of the oxidizer channel into the combustion chamber results there at the high-calorific design point. "Similar" here means, for example, between +/-50%, preferably between +/-20%, particularly preferably between +/-10% of the speed at the outlet. The similar speed results in high stability when mixing the fuel while avoiding detachments, which can lead to unstable combustion and even thermoacoustic oscillations.

Alternatively, the fuel orifice has a flow cross section, in particular with a diameter d ₃ , which corresponds to the flow cross section, in particular with a diameter d ₂ , of the fuel channel running upstream. The flow cross section is z. B. in such a way that there in the low-caloric design point a speed similar (as defined in the previous paragraph) of the fresh gases sets in at the outlet of the oxidizer channel, with the advantages mentioned above.

In the burner system according to claim 1, the further feed opening is formed by at least one bypass opening, the bypass opening being formed in the wall upstream of the fuel orifice and the further flow section forming a flow connection between the flow paths of the oxidizer and the fuel. In the event that a fresh gas component (fuel or oxidizer) flows through the bypass opening, the bypass opening serves to partially combine the fresh gases upstream of the fuel orifice. The separate flow sections of the flow paths are then located upstream of the bypass opening. The complete combination of fuel and oxidizer preferably continues to take place downstream of the fuel orifice. It has been shown that such an arrangement of the bypass opening upstream of the fuel orifice advantageously allows the mass or volume flow which flows through the fuel orifice to be at least partially balanced between the high-calorific and the low-calorific design point. In this way, similar velocities at the fuel orifice can advantageously be achieved in the low-calorific and high-calorific design point, which deviate from one another by a factor of less than 2, in particular by less than 1.5, preferably by less than 1.2. In this way, similar inflow and mixing characteristics can advantageously be achieved in the two design points, which form a prerequisite for stable, efficient and low-emission operation.

In the burner system according to claim 1, the flow cross section of the fuel mouth is preferably designed in such a way that in the low-calorific design point or in the high-calorie design point the velocity at the fuel mouth is between +/- 50%, preferably between +/- 20% of the velocity of the fresh gas mixture at the Leakage into the combustion chamber is, wherein the proportion flowing through the bypass opening is (at least substantially) equal to zero. In the corresponding design point, operation is then possible in which, as is known from the prior art, the fuel and oxidizer streams flow separately up to the fuel orifice and there (completely) be merged. This advantageously enables a simple design, starting from a configuration (eg known from the prior art) without a bypass opening. The flow section with the bypass opening is designed (designed and/or arranged) in such a way that with a different fuel (which has a different calorific value), a proportion of fuel or oxidizer can flow through the bypass opening and into the flow path with the other fresh gas component. Differences in fuel volume flows can be compensated for, at least in such a way that the velocity at the fuel orifice remains in a similar range, as indicated above. The design is usually carried out using computer-aided flow simulation.

For example, the following advantageous method results in a design starting from the low-calorific design point, with the fuel orifice expediently having a flow cross section corresponding to the fuel channel: At the low-calorific design point, with the high fuel mass or volume flow, fuel and oxidizer flow separately up to the fuel orifice and are completely merged there. The pressure ratios in the oxidizer and fuel channel are similar in the low-calorific design point, so that the proportion of fresh gas, in this case oxidizer, flowing through the bypass opening is (essentially) zero. At the high-calorific design point, with the low fuel mass or volumetric flow, there is then a lower pressure loss 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 causes oxidizer to flow into the fuel channel through the bypass opening in such a way that the pressure conditions balance out. This proportion of oxidizer increases the mass or volume flow in the fuel channel downstream of the bypass opening, while the oxidizer flow is reduced. The further flow section with the bypass opening, in particular its angle and flow cross section, are designed in such a way that the proportion of oxidizer flowing through the bypass opening results in such a way that the speed at the fuel mouth compared to the low calorific design point (as indicated above), with the advantages indicated above. In particular, the total flow cross section of the bypass opening and/or the further flow section is smaller than the smallest flow cross section in the fuel channel (with the fuel port), with z. B. between 10% and 70% of the smallest cross-section. The proportion of oxidizer can result, for example, in such a way that the oxidizer mass flow through the bypass channel corresponds to up to 5 times the fuel mass flow. It has been shown that in the case of fuel compositions with a calorific value or Wobbe index between that of the low-calorific and the high-calorific fuel, a correspondingly lower proportion is established, which leads to similar speeds.

In a design based on the high-calorific design point, the following advantageous method results, for example, with the fuel orifice expediently having a reduced flow cross section of the fuel orifice compared to the fuel channel: At the high-calorific design point, with the low fuel mass or volume flow, fuel and oxidizer flow separately up to to the fuel orifice and are completely brought together there. The pressure conditions in the oxidizer and fuel channels are similar in the high calorific design point. In addition, due to the oxidizer flowing around the fuel channel, an aerodynamic obstruction of the further flow section with the bypass opening results. As a result, the proportion of fresh gas, here fuel, flowing through the bypass opening is (essentially) zero. At the low-calorie design point, with the high fuel mass or volume flow, there is a higher pressure loss in the fuel channel than in the oxidizer channel, in particular due to the reduced flow cross section of the fuel orifice. This results in a pressure difference between the oxidator and the fuel channel, which causes fuel to flow into the oxidator channel through the bypass opening in such a way that the pressure conditions balance out. The mass or volume flow in the fuel channel downstream of the bypass opening is reduced by the outflowing fuel portion, while the volume flow in the oxidizer channel is increased. The further flow section with the bypass opening, in particular its angle and flow cross-section, are designed in such a way that the proportion of fuel flowing through the bypass opening results in such a way that the velocity at the fuel orifice is similar (as stated above) compared to the high-calorific design point. In particular, the total flow cross section of the bypass opening and/or the further flow section is smaller than the smallest flow cross section in the fuel channel. The proportion can be between 30% and 90% of the total fuel mass flow, for example. It has been shown that in the case of fuel compositions with a calorific value between that of the low- and the high-calorific fuel, a correspondingly lower proportion is established, which leads to similar speeds.

If several flow sections are present, which are particularly symmetrical to each other, e.g. B. are arranged rotationally symmetrically about the central axis and axially at the same height, a symmetrical introduction of a fresh gas component can be achieved in the other fresh gas component. This promotes even mixing, which in turn supports low-emission combustion.

In 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 section of the oxidizer channel, which preferably has such an axial length that inflow effects of the oxidizer flow when it flows into the oxidizer channel, in particular local flow separations, at the Bypass opening have subsided substantially. “Essentially” here means that the inflow into or out of the bypass opening is not significantly influenced by unsteady flow phenomena. Furthermore, an arrangement in the oxidizer channel advantageously reduces the risk of fuel flowing back into an oxidizer plenum reduced, as could occur, for example, with a short-term flow reversal in transient states (e.g. ignition processes, etc.). For example, the length of the inflow section can correspond at least to the diameter of the bypass opening.

In 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 section of the end section (of the fuel channel), which preferably has such an axial length that inlet effects occur when the one fresh gas component flows in through the bypass opening have essentially decayed by the fuel orifice. "Substantially" here means that the flow from the fuel orifice is not significantly influenced by unsteady flow phenomena. In this way, a uniform, stable mixing of the (possibly remaining) fuel into the oxidizer can be achieved in the mixing chamber located downstream. The length of the outflow section can be at least 0.5 times the inner diameter of the fuel channel, for example. The length of the inflow and/or outflow section can be designed in particular with the aid of computer-aided flow simulation.

The desired flow guidance with the desired proportion flowing through the bypass opening can be supported in the burner system according to claim 1 in that the further flow section comprises a bypass channel in the wall, which runs radially-axially at an angle with respect to the central axis (of the fuel channel). The bypass channel opens downstream into the bypass opening. In this way, a flow direction of one fresh gas component into the other, which does not correspond to the design, is made more difficult.

It can be advantageous in one embodiment that the angle is between 0° and 90°, in particular between 10° and 60°, e.g. B. is between 15 ° and 45 °. The angle is measured between the bypass channel longitudinal axis and the Centerline (relative to the upstream leg of the centerline). This design supports a (possibly optional) flow of the oxidizer into the fuel channel and makes it more difficult for fuel to flow out into the oxidizer. This design of the bypass channel is expedient, for example, in combination with a flow cross section of the fuel orifice corresponding to the fuel channel, which allows an advantageous design based on the low-calorific design point.

In an alternative embodiment, it can be advantageous for the angle to be between 90° and 180°, in particular between 110° and 170°, e.g. B. is between 130 ° and 165 °. This design supports a flow of fuel into the oxidizer channel (which is optional depending on the design) and makes it more difficult for oxidizer to flow into the fuel channel. This design of the bypass channel is expedient, for example, in combination with a reduced flow cross section of the fuel orifice compared to the fuel channel, which allows an advantageous design based on the high-calorific design point.

In the burner system according to claim 1, the oxidizer channel preferably comprises a first section in its axial course and a second section downstream of the first section, with a cross-sectional reduction being arranged between the two sections. In this case, the fuel orifice is arranged axially on, within or downstream of the cross-sectional reduction. The reduction in cross section can be designed, for example, as a step, conical or continuous. This arrangement of the fuel orifice means that the fuel is (completely) added to the flow that is accelerated immediately downstream or to the flow that has already been accelerated. This advantageously counteracts (undesirable) flame stabilization at the fuel orifice.

In the burner system according to claim 2, the oxidizer / fuel supply arrangement comprises a (possibly further) mixing chamber, which is centrally located on the Longitudinal axis arranged and formed symmetrically to this. The mixing room is on the bottom by a z. B. aligned perpendicular to the longitudinal axis L, bottom wall and peripherally limited by a wall and z. B. cylindrical. Downstream, the mixing chamber opens into the combustion chamber with an outlet. The fresh gas components can be fed to the mixing chamber in such a way that a swirling (or rotating) flow with 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 a multi-stage, in particular a 2-stage, burner system, in which case the oxidizer/fuel supply arrangement can be assigned in particular to a pilot stage. A combination with several oxidizer/fuel assignments according to one of the above embodiment variants is particularly advantageous, in particular as the main stage. The cross section of the mixing chamber perpendicular to the longitudinal axis is preferably smaller than that of the combustion chamber. The length of the mixing chamber in the axial direction is at least so large that fresh gas outlets can be introduced on the peripheral side and preferably that an at least partial premixing of the fresh gas components results up to the outlet. The mixing chamber, like the combustion chamber (in particular when assigned to a pilot stage), can be introduced into a burner head body, for example.

In the burner system according to claim 2, the oxidizer/fuel supply arrangement preferably has at least one oxidizer duct, which opens into the mixing chamber on the peripheral side and which is aligned with a tangential (and optionally a radial) directional component with respect to the longitudinal axis, the oxidizer duct corresponding to the separate flow section of the oxidizer assigned. The oxidizer channel forms, for example, a flow connection between the air distribution space and the mixing space. For a uniform, symmetrical introduction into the mixing space, there are preferably a plurality of oxidizer channels, for example three, which are arranged in particular in a rotationally symmetrical manner about the longitudinal axis. Run in the presence of multiple oxidizer channels and these open out, for example, axially at the same level, lying in a plane perpendicular to the longitudinal axis. In this way, the oxidizer flow can be effectively imparted with a rotational movement to generate a swirl.

In the burner system according to claim 2, a distribution area for fuel is assigned in an advantageous embodiment of the oxidizer / fuel supply arrangement, which is particularly symmetrical to the z. B. is arranged centrally on the longitudinal axis (or the longitudinal axis and / or axis of symmetry of the mixing chamber) and / or adjacent to the back of the bottom wall. For example, the distributor area is arranged in a burner head body. In particular, the cross-sectional area (perpendicular to the longitudinal axis) of the distributor area is radially the same as or larger than that of the mixing space. In this way, the bottom side of the mixing chamber can be effectively cooled by the inflowing fuel. In particular in connection with a fuel supply arranged centrally on the longitudinal axis, which feeds the fuel z. B. perpendicular to the bottom wall in the distribution area, the fuel can collide with the bottom wall and thus bring about an effective impact cooling.

An advantageous operation, in particular with low-calorific fuel, is achieved with the burner system according to claim 2 in that the first supply opening is formed by at least one first fuel orifice, which opens out into the mixing chamber on the peripheral side and which forms the downstream end of a first fuel duct, the fuel duct being equipped with a End section with a tangential (and optionally radial) directional component with respect to the longitudinal axis. The end section of the fuel channel is preferably directed in the same direction as the oxidizer channel, ie with a corresponding tangential and possibly radial directional component. In this way, the fuel flow can advantageously contribute to the generation of the swirl flow, which leads to a comparatively low pressure loss. The fuel channel preferably forms a flow connection between the distribution area and the mixing space. Upstream of the final section For example, the fuel passage is axially aligned for flow communication with the manifold area.

In this case, an oxidator orifice of the oxidator channel and the first fuel orifice are preferably arranged axially offset from one another, particularly if there are several oxidator or fuel channels, with the axial lower edge of the oxidator orifice being arranged upstream of the axial lower edge of the fuel orifice. The lower edge of the oxidizer outlet can be flush with the bottom wall, for example. In this way, the fuel flow can be entrained by the swirling oxidizer flow. In the case of flame stabilization in the mixing chamber, a certain distance from the bottom wall remains, and in particular the thermal load on the bottom wall is reduced by the intermediate air flow. Three channels have proven to be an advantageous number of oxidizer and fuel channels, which alternately open into the mixing chamber on the circumferential side and are arranged rotationally symmetrically to the longitudinal axis, each offset by 60°. As a result, the fresh gases can be mixed well into one another with effective generation of swirl.

Alternatively or additionally, the overall flow cross-section of the first fuel orifice is designed in such a way that the inflow velocity of the fuel into the mixing chamber at the low-calorific design point is between 10% and 120%, in particular between 15% and 80% of the velocity of the oxidizer at the oxidator orifice. The speed of the oxidizer is such that sufficient swirl generation for flame stabilization is achieved and can be between 50 m/s and 120 m/s, for example. The total flow cross-section results from the sum of the flow cross-sections of certain flow sections or orifices, here the first fuel orifices that are present. The impulse of the high fuel mass or volume flow can thus advantageously contribute effectively to the generation of swirl. In addition, it is avoided that the rotational movement of the oxidizer flow is slowed down by the high fuel flow, which could impair flame stabilization.

In the burner system according to claim 2, the further feed opening is formed by a second fuel orifice into the mixing chamber and the further flow section comprises a second fuel channel which is connected with an axial directional component, e.g. B. parallel to the longitudinal axis. Preferably, there may be a plurality of second fuel ports and passages for even introduction of fuel. The overall flow cross-section of the second fuel port is preferably such that the velocity at the high calorific design point z. B. is between 30% and 80% of the velocity of the oxidizer at the oxidizer orifice. In particular, the total flow cross section of the second fuel port and/or the second fuel channel is smaller than the (total) flow cross section of the first fuel channel, and is z. B. between 4% and 40% of the total flow area of the first fuel channel. In addition, the channels can have a radial directional component. The channels, like the fuel and the oxidizer channel, e.g. B. be formed by a circular cross-section bore. Thus, several separate flow sections through which fuel can flow in parallel can advantageously be provided, through which different proportions of fuel flow depending on the calorific value of the fuel. This enables operation with both high, medium and low-calorific fuels, with good mixing of the fuels and stable combustion being achievable in each case.

In the burner system according to claim 2, the second fuel port is preferably arranged in the mixing space at a location at which a lower pressure prevails in a high-calorific design point (or with pure oxidizer flow) than at a location of the first fuel port. The location can, in particular when there are several (first and/or second) fuel orifices, also be an area. For example, the pressure may be between 0.1% and 2% lower than at the location of the first fuel port. In this way, an advantageous aerodynamic distribution of the fuel flow can be achieved, which changes with a change in the calorific value in such a way that good mixing and sufficient swirl generation for stable combustion can be achieved for different fuel qualities: In the high-calorific design point, (almost) the entire flow Fuel flow (a proportion of approx. 100%) via the second fuel channel (or channels) into the mixing chamber. This is caused by the pressure differential, which is greater across the second fuel channel than across the first fuel channel, and an aerodynamic obstructing effect of the swirling oxidizer flow with respect to the first fuel orifices. The aerodynamic conditions largely prevent a flow of the high-calorific fuel via the first fuel channel(s), which would not mix sufficiently into the oxidator swirl flow due to the low momentum of the high-calorific fuel. The comparatively low axial mass flow of the high-calorific fuel can be accelerated and entrained by the rotational movement of the air, so that stable combustion can be achieved. The total flow cross section (sum of the flow cross sections) of the second fuel channels is significantly smaller than the total flow cross section of the first fuel channels. The overall flow cross-section is so small that at the low-calorific design point with the high fuel mass or volume flow (fuel flow for short) there would be a pressure loss that is higher than the pressure difference due to the arrangement of the second fuel ports. As a result, a portion (for example more than 30%, in particular more than 50%) of the fuel flows via the first fuel duct/fuel ducts, the remaining portion flows via the second fuel duct/fuel ducts. In this way, the high fuel flow in the low-calorific design point supports the rotational movement. If the entire fuel flow were introduced in the low-calorific design point via axial fuel channels, the angular momentum of the air would not be sufficient to cause the rotational movement maintained to such an extent that stable combustion would be achieved.

In a particularly easy-to-manufacture design variant according to the burner system according to claim 2, the second fuel channel forms a flow connection between the distributor area and the mixing chamber and runs through the bottom wall, with the second fuel orifice in particular being positioned axially at the level of the mixing-chamber-side surface of the bottom wall. For example, the second fuel orifice is arranged radially offset from the central axis, for example between 1/4 and 3/4 of the diameter of the mixing chamber. This is particularly advantageous when there are a plurality of fuel orifices, which are preferably arranged symmetrically about the central axis. If there is only one fuel orifice, it can be arranged on the central axis.

An advantageous burner system, which allows stable operation over a wide operating range with high-, medium- and low-calorific fuels, results when at least two oxidizer/fuel arrangements are present, with one, preferably several, for flame stabilization in the manner of a recirculation-stabilized jet flame burner ( preferably as a main stage) and one for flame stabilization via a swirl flow (preferably as a pilot stage). The oxidizer channels are preferably fed via a common oxidizer distribution space, while separate distribution regions are assigned to the fuel channels.

Advantageous variants of the method correspond analogously to the variants that have been described in connection with the burner system according to claim 1 or claim 2 .

Fig. 1

ein Brennersystem einer Gasturbinenanordnung zum Betrieb mit nieder-, mittel- und hochkalorischen Brennstoffen mit zwei erfindungsgemäßen Oxidator-/Brennstoffzufuhranordnungen in einem Längsschnitt,

Fig. 2 A-C

schematische Darstellungen eines Teils der Oxidator-/Brennstoffzufuhranordnung zur axialen Oxidatorzufuhr in eine Brennkammer gemäß Fig. 1, ohne Strömungsführung und mit angedeuteter Strömungsführung in zwei unterschiedlichen Betriebspunkten, im Längsschnitt,

Fig. 3 A-C

schematische Darstellungen eines Teils einer weiteren Variante einer Oxidator-/Brennstoffzufuhranordnung zur axialen Oxidatorzufuhr in eine Brennkammer, ohne Strömungsführung und mit angedeuteter Strömungsführung in zwei unterschiedlichen Betriebspunkten, im Längsschnitt,

Fig. 4

eine schematische Darstellung eines Brennerkopfes des Brennersystems nach Fig. 1 mit den beiden Oxidator-/Brennstoffzufuhranordnungen in Ansicht von vorne, aus Richtung einer Brennkammer,

Fig. 5

einen Teil des Brennerkopfes gemäß Fig. 4 mit einer Oxidator-/Brennstoffzufuhranordnung zur Drallerzeugung in einer perspektivischen Schnittdarstellung durch Oxidator- und Brennstoffkanäle und

Fig. 6 A, B

schematische Darstellungen eines Teils der Oxidator-/Brennstoffzufuhranordnung gemäß Fig. 5, im Betrieb bei zwei unterschiedlichen Betriebspunkten, im Längsschnitt.

The invention is explained in more detail below using exemplary embodiments with reference to the drawings. Show it:

1

a burner system of a gas turbine arrangement for operation with low-, medium- and high-calorific fuels with two oxidizer/fuel supply arrangements according to the invention in a longitudinal section,

Fig. 2AC

Schematic representations of a portion of the oxidizer/fuel delivery arrangement for axial oxidizer delivery into a combustor according to FIG 1 , without flow control and with indicated flow control in two different operating points, in longitudinal section,

Fig. 3AC

Schematic representations of part of a further variant of an oxidizer/fuel supply arrangement for axial oxidizer supply into a combustion chamber, without flow guidance and with indicated flow guidance at two different operating points, in longitudinal section,

4

a schematic representation of a burner head of the burner system 1 with the two oxidizer/fuel supply arrangements in front view, from the direction of a combustion chamber,

figure 5

part of the burner head according to 4 with an oxidizer / fuel supply arrangement for generating swirl in a perspective view Sectional view through oxidizer and fuel channels and

Fig. 6 A, B

Schematic representations of a portion of the oxidizer/fuel delivery assembly according to FIG figure 5 , in operation at two different operating points, in longitudinal section.

1 shows a burner system 1 of a gas turbine arrangement, in particular a micro gas turbine arrangement, for operation with low-, medium- and high-calorific fuels in a longitudinal section. During operation, the burner system 1 burns oxidizer and fuel to form hot gas as the working medium for the gas turbine arrangement. The oxidizer is usually formed by air, which can also contain other components, e.g. B. externally recirculated exhaust gas or thermally usable hydrocarbons. Exhaust gas containing oxygen is also possible. In the following, the term "air" is used synonymously with the more general term "oxidizer".

The burner system 1 extends along a longitudinal axis L, which represents the axis of symmetry here by way of example. As in 1 indicated, the burner system 1 with a combustion chamber 6 is installed in a pressure housing, more precisely in a pressure housing space 12 surrounded by a pressure housing wall 10, of a gas turbine arrangement. The pressure housing is z. B. pressure-tight connected to a turbine housing (not shown here).

The combustion chamber 6 comprises a combustion chamber 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 of cylindrical design, for example, which is advantageous for a symmetrical, uniform and therefore low-emission combustion process is. At the downstream end of the combustion chamber 24, the peripheral wall 20 ends in an outlet opening 22, via which the combustion chamber 6 is connected to an exhaust pipe 8 of the gas turbine arrangement.

Mixed air openings 18 are introduced circumferentially in the peripheral wall 20 and are arranged axially in the peripheral wall 20 in such a way that they are located downstream of a combustion zone during operation.

The peripheral wall 20 runs coaxially to an outer wall 14 of the combustion chamber 6, which is arranged around the peripheral wall 20 to form a circumferential gap, here in the form of a circular ring. The gap forms a feeder duct 16 for the countercurrent supply of air into an air distribution space 30 of a burner head 4. A different configuration of the air supply is also possible.

The burner head 4 of the burner system 1 is arranged upstream of the combustion chamber 6 . The burner head 4 comprises a support plate 32 into which a distribution area 38 for the fuel of the main stage is integrated. The distribution area 38 is designed here, for example, as an annular plenum running around the longitudinal axis L and is fed by a fuel supply 34 . The support plate 32 forms a front end closure of the pressure housing space 12 and is connected to the pressure housing wall 10 via fastening devices 31 for pressure-tight sealing of the pressure housing space 12 . Between the support plate 32 and the pressure housing space 12 or the combustion chamber 6, a flat insulating means 33 of the burner head 4 is arranged for thermal insulation.

The burner head 4 includes here, for example, separate air/fuel supply arrangements 50, 60. The air/fuel supply arrangements 50 are assigned to a main stage of the burner system 1 and are used to add the fresh gas components Air and fuel into the combustion chamber 24. The air/fuel supply arrangements 50, ten in number in the present example, are arranged equidistantly on an imaginary circular ring to form a nozzle ring. This arrangement advantageously contributes to a small axial extent of the combustion zone.

The air/fuel supply arrangement 60 is assigned to a (stabilizing) pilot stage of the burner system 1 and serves to supply the fresh gas components air and fuel to a second (pilot) combustion chamber 26. The second combustion chamber 26 is arranged upstream of the combustion chamber 24 and opens into the combustion chamber 24 with an opening 28, wherein in the present case it is embodied on the longitudinal axis L and symmetrically, in particular cylindrically, thereto. The air/fuel assemblies 50 are arranged with air ducts 504 circumferentially around the second combustion chamber 26 . The air ducts 504 and the combustion chamber 26 are here, for example, incorporated into a burner head body 25 made of solid material. Another configuration is also possible, for example with (thinner) walls. At stationary operating points, the larger air and fuel mass flow is usually routed through the main stage.

A fuel feed system 2 of the burner system 1 is used for the separate feed of fuels for the main and pilot stages into the main stage manifold area 38, via the fuel feed 34, and into a second pilot stage manifold area 40 via a second fuel feed 36. The fuel mass flows are preferably separate control - Or adjustable, with different fuels can be used.

The first air/fuel supply arrangements 50 are designed to supply the fresh gas components, air and fuel, axially, parallel to the longitudinal axis L, with a high momentum to form a large-scale recirculation flow into the combustion chamber 24 to bring in. For this purpose, the air/fuel supply arrangements 50 have the air ducts 504, which are arranged in a circular ring to form the nozzle ring. The air ducts 504 each open into the combustion chamber 24 with an outlet 512 and are aligned in the longitudinal direction along a central axis M running parallel to the longitudinal axis L. The air ducts 504 have their upstream ends in flow communication with the air plenum 30, which here forms an air plenum, and from which they are supplied with air.

How accurate Figure 2A As can be seen, the air ducts 504 each have an upstream first section 520 and a downstream second section 522 which is reduced in cross-section compared to the first section 520 for accelerating the flow. The sections 520, 522 are each in particular cylindrical, although another cross-sectional shape is also conceivable. The reduction in cross section between the two sections 520, 522 can, for. B. as a cross-sectional jump, be conical or continuous.

The air/fuel supply arrangements 50 each have fuel channels 502 protruding into the air channels 504 . The fuel channels 502 are each delimited by a wall 501 and arranged on the central axis M in the longitudinal direction. The fuel channels 502 form a flow connection from the fuel distribution area 38, extending therefrom through the insulating means 33 and the air distribution space 30 and are each arranged with end portions 503 within the air channels 504 coaxial thereto. The fuel passages 502 open into the air passages 504 with fuel ports 510 for the coaxial addition of fuel into the air. The fuel orifices 510 are positioned axially immediately at the beginning of, within, or downstream of the area reduction.

The fuel orifices 510 each form first feed openings for feeding fuel into the air flow. Upstream of the fuel ports 510, the flow paths of the fresh gas components run at least partially in separate flow sections. Mixing spaces 508 are formed in the air passages 504 downstream of the fuel ports 510, in which the flow paths of air and fuel are merged, i. H. in the mixing chambers, the entire fuel flow is introduced into the air flow. The mixing chambers 508 are used for the at least partial premixing of fuel and air upstream of their feed into the combustion chamber 6 or the combustion chamber 24.

According to a core idea of the invention, the air/fuel supply arrangements 50 include not only the fuel openings 510, as the first supply openings, but also further flow sections with further supply openings. The further flow sections are formed here, for example, by several, for example four, bypass channels 526. The bypass channels 526 are z. B. introduced rotationally symmetrically circumferentially around the central axis and axially at the same height in the walls 501 of the fuel channels 502. For example, they have a circular cross section.

The bypass openings 528 are arranged within the air channel 504 axially upstream of an outflow section 516 of the end section 503 of the fuel channel 502 . The end section 503 extends between the downstream edges of the bypass openings 528 and the fuel ports 510. The length of the outflow section 516 is selected such that inflow effects when one fresh gas component, in this embodiment particularly air, flows into the other up to the fuel port 510 at least largely have subsided. For example, there is no longer any recirculation flow at the fuel orifice 510 .

Further, the bypass openings 528 (having the upstream edges) are located downstream of inflow portions 514 within the air ducts 504 . The length of the inflow sections 514 is such that inlet effects of the air flow when it flows into the air ducts 504, in particular z. B. recirculation areas at the inlet opening, until the bypass channels 526 have subsided. Furthermore, in this way the probability can be reduced that, in the event of a short-term flow reversal during an unsteady maneuver, fuel will get into the air distribution area 30 . For this purpose, the air ducts 504 may have a greater length than the recirculation-stabilized jet flame burners known from the prior art.

in the in 1 indicated, first training variant, which is more precisely in the Figures 2A to 2C As shown, the air/fuel supply assemblies 50 are designed from a low calorific design point (a design operating point for operation with a low calorific design fuel, such as a syngas having a calorific value of 5 MJ/kg). The flow cross sections or here diameter d ₃ of the fuel openings 510 and the flow cross sections or diameter d ₂ of the fuel channels 502 correspond to one another.

In the Figures 3A to 3C a second embodiment variant is shown, in which the air/fuel supply arrangements 50 are designed starting from a high-calorific design point (a design operating point for operation with a high-calorific design fuel, for example natural gas with a calorific value of just under 50 MJ/kg). The flow cross section at the fuel orifice 510, or here the diameter d ₃ , is reduced compared to the flow cross section or the diameter d ₂ of the fuel channel 502 by the Accelerate fuel flow to a desired velocity at fuel orifice 510.

In both exemplary embodiments, the diameters d ₃ are designed in such a way that the speed of the (low-calorific or high-calorific design) fuel at the fuel orifice 510 is similar to the speed of the fresh gas mixture at the outlet 512 into the combustion chamber 24 (for example between +/-50% , especially between +/- 20%). At the outlet 512 there are typical velocities for a recirculation-stabilized jet flame burner, for example between 60 m/s and 180 m/s. The similar entry velocities prevent flow separation and associated fuel fluctuations at the fuel orifice 510 and support a stable combustion process.

The bypass channels 526 here run radially-axially, for example, inclined at an angle α with respect to the central axis M. In the first exemplary embodiment, the angle α is ( Figures 2A to 2C ) e.g. B. between 15 ° and 45 ° (open α direction upstream). In the second embodiment ( Figures 3A to 3C ) is the angle α z. B. between 135 ° and 165 ° (a direction upstream open). These orientations each support a desired direction of flow between the air flow path and the fuel flow path, discussed below.

The angle α and the total flow cross-sections of the bypass channels 526 and/or the bypass openings 528 (ie 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 exemplary embodiment and with respect to the low-calorific design point in the second exemplary embodiment. The design is such that the velocities at the fuel orifices 510 in the high-caloric or low-caloric design point is matched to the velocities in the low-caloric or high-caloric design point, ie the velocities are similar. For example, the "low calorific/high calorific" velocity ratio at the fuel orifices 510 is less than a factor of 2, preferably less than a factor of 1.5.

The flow control during operation is in the first embodiment in the Figures 2B and 2C indicated by arrows. Figure 2B shows the flow control in the low-caloric design point, with a large fuel mass or volume flow. Air and fuel are first introduced to the bypass opening through the air channel 504 and the fuel channel 502 in separate flow sections. The pressure ratios in the air passage 504 and the fuel passage 502 are similar at the low caloric design point, so that the proportion of air flowing through the bypass opening 528 is (substantially) zero. Therefore, there is no or at most a small driving force that causes a flow through the bypass openings 528 . Consequently, the air flows (at least for the most part) through the air duct 504 and the fuel through the fuel duct 502 essentially separately up to the fuel port 510, where the fresh gas components are combined.

In the high calorific design point ( 2C) , with the significantly lower fuel volume flow, there is less pressure loss in the fuel duct 502 than in the surrounding air duct 504. The resulting pressure difference causes a proportion of the air to flow through the bypass ducts 526 with the bypass openings 528 already upstream of the fuel orifice 510 into the fuel duct 502 flows in. This increases the volume flow within the fuel channel 502 between the bypass openings 528 and the fuel orifice 510. The proportion of air results from the appropriate design of the bypass channels 526 and the bypass openings 528 in such a way that the desired velocity is present at the fuel orifice 510 . In this case, diameter d ₁ of the bypass channels 526 z. B. between 10% and 40% of the diameter d ₂ of the fuel channel 502 amount. This significantly increases the stability of the combustion by avoiding fuel fluctuations at the fuel orifice. Without the configuration with the bypass channels 526, speed differences by a factor of 5 would result, for example.

For the second embodiment, the flow control is in operation in the Figures 3B and 3C indicated by arrows. Figure 3B shows the flow control in the low-calorific design point, with a large fuel volume flow. Air and fuel are first introduced to the bypass opening 528 through the air channel 504 and the fuel channel 502, respectively. Due to the high fuel mass or volume flow, a high pressure drops at the fuel orifice 510 . An increased pressure correspondingly arises upstream in the fuel channel 502 , which leads to an increased pressure difference between the fuel channel 502 and the surrounding air channel 504 . The pressure difference causes a proportion of the fuel to flow through the bypass channels 526 with the bypass openings 528 into the air channel 504 to equalize the pressure. Downstream of the bypass openings 528, a portion of the fuel flow flows together with the air flow to the location of the fuel orifice 510, the other portion continues to flow separately via the fuel channel 502 to the fuel orifice 510. The bypass channels 526 with the bypass openings 528 are particular with regard to their angle α and the flow cross-sections are designed to cause a pressure differential that proportionately divides the fuel flow such that the velocity at fuel orifice 510 is similar (e.g., by a factor of 2 or less, preferably by a factor of 1.3 or less) to this Velocity is at the high calorific design point. The diameters d ₁ of the bypass channels 526 e.g. B. between 10% and 50% of the diameter d ₂ of the fuel channel 502 amount.

In the high-calorific design point, with the comparatively low fuel volume flow, the pressure conditions between the fuel channel 502 and the air channel 504 are similar to one another. Therefore, there is no or at most a low driving force for the flow through the bypass channel 526 with the bypass opening 528.

The fuel compositions in the low-calorific and in the high-calorie design points preferably represent extremes between which the fuel compositions move during operation. If the fuel composition and the calorific value or Wobbe index of the fuel change between these extremes during operation, the pressure conditions within the air/fuel supply arrangements 50 adjust accordingly in such a way that the proportion of the respective fresh gas that flows into the flow path of the other fresh gas , is so large that the desired equalization of the velocities occurs.

The second air/fuel supply arrangement 60 (cf. 1 and figure 5 , 6A, B ) is designed to supply the fresh gas components, air and fuel, to the second combustion chamber 26 in a swirling flow, ie with a tangential directional component. For this purpose, the air/fuel supply arrangement 60 comprises a mixing chamber 608 which is formed on the bottom side in the inner wall, upstream, of the combustion chamber 26 so that it opens into the combustion chamber 26 downstream with an outlet 612 . The mixing chamber 608 is arranged centrally, on the longitudinal axis L, and is embodied symmetrically to this, in particular cylindrically. As the Figures 6A , B show in more detail, the mixing chamber 608 is delimited on the bottom by a bottom wall 626, which is oriented perpendicular to the longitudinal axis L here, for example. The mixing chamber 608 is delimited by a wall 609 on the peripheral side. The mixing space 608 is used for at least partial premixing of the fresh gas components.

As the Figures 4 and 5 show more precisely, several air ducts 604 with air openings 610, three in number here by way of example, open out into the mixing chamber 608 in the wall 609 on the peripheral side. The air channels 604 form a flow connection between the air distribution space 30 and the mixing space 608 and form separate flow sections of the flow path of the air, here by way of example for the pilot stage. The air ducts 604 have a circular cross section, for example. The air ducts 604 run, for example, axially constant, in a plane perpendicular to the longitudinal axis L, and are aligned tangentially to the cylindrical mixing space 608 in order to impress the exiting air flow with a tangential directional component for generating the swirl flow. The alignment could also have a radial directional component.

Preferably alternately to the air ducts 604, in the same number, fuel ducts 602, in the present example three, open with fuel openings 614 peripherally into the mixing chamber 608. The alternating arrangement enables a more uniform mixing of the fuel into the air. The fuel channels 602 have, for example, a circular cross section and separate flow sections of the flow paths for the fuel. The openings of the air and fuel channels are arranged rotationally symmetrically to the longitudinal axis L, here offset by 60° to one another, for example. The fuel channels 602 each have an end section 601 that runs axially constantly in a plane perpendicular to the longitudinal axis L and tangentially, possibly with an additional radial directional component, to the mixing chamber 608.

The end sections 601 of the fuel channels 602 are directed tangentially-radially, preferably in the same direction as the air channels 604 . In this way, the fuel can drive the rotational movement of the swirl flow. The fuel channels 602 are designed in such a way that in the low-calorific design point with the higher mass or volume flows, the rotational movement of the swirl flow is also driven. The fresh gas components each have similar magnitudes at the inflow velocities into the mixing chamber 608, the fuel velocity being, for example, 10% and 120%, in particular between 15% and 80%, of the air velocity. The air speed can be between 50 m/s and 120 m/s, for example, and is such that a flame-stabilizing swirl flow is achieved.

The fuel orifice 614 and the air orifices 610 are arranged axially offset from one another, with the axial lower edges of the fuel orifices 614 being arranged further downstream than the axial lower edges of the air orifices 610. The air orifices 610 can, for example, have their axial lower edges flush with the bottom wall 626. The air flow, which is generally much larger, can thus advantageously counteract an undesirable stabilization of a flame at the fuel orifice 610 .

Upstream of the end sections 601 , the fuel channels 602 have axial sections 605 that branch out from the distributor area 40 . The distribution area 40 is arranged centrally on the longitudinal axis L and is adjacent to the rear of the bottom wall 626 . The radial extension of the distributor area 40 is greater than that of the mixing chamber 608, so that the fuel flow can be fed from the distributor area 40 simply via the axial sections 605 and the end sections 601 arranged downstream to the mixing chamber 608.

The distribution area 40 is fed by the second fuel feed 36 arranged centrally on the longitudinal axis L. FIG. The central arrangement of the fuel feed 36 and the distributor area 40 with its arrangement adjacent to the rear of the bottom wall 626 advantageously enables cooling of the bottom wall 626 by means of the supplied fuel flow, which impinges on the rear of the bottom wall 626 and cools it in the manner of impingement cooling. The fuel channels 602, which are arranged uniformly around the mixing chamber 608 and have the axial sections 605 and end sections 601, also contribute to the cooling of the mixing chamber 608. In this way, the temperature load in the burner head 4 is advantageously reduced in some areas. Temperature-sensitive components, such as an ignition device or bearing points, can be arranged in these areas. This has a positive effect on the service life of the individual components of burner system 1.

The fuel orifices 614 form a group of first supply openings, with the fresh gas components fuel and air being brought together in the mixing space 608 . According to a core concept of the invention, further flow sections, formed by second fuel channels 603, are present, which each open into the mixing chamber 608 of a group via further feed openings, formed by second fuel ports 616. The second fuel channels 603 are aligned axially with respect to the longitudinal axis L, although they can also have a radial component. The second fuel openings 616 are arranged in the mixing chamber 608, in particular in the bottom wall 626, at a location B (here area) at which there is a lower pressure in the high-calorific design point than at a location A (here area) of the first fuel openings 614. Such a place is z. B. flush with the side of the bottom wall 626 pointing in the direction of the mixing chamber 608, radially offset from the longitudinal axis L. Such an arrangement results in operation at the high-calorific design point a pressure difference, as a result of which the fuel preferably flows into the mixing chamber 608 via the second fuel channels 603 and the second fuel openings 616 . The flow cross sections or the total flow cross section of the second fuel channels 603 are designed such that the speeds at the second fuel ports 616 z. B. be between 30% and 80% of the speed of the air flow. This advantageously brings about good mixing of the fuel into the swirled air flow. In the high-calorific design point, the fuel flow is (almost) 100% via the second fuel channels 603 and (almost) 0% via the first fuel channels 602 .

In the Figures 6A and 6B the flow control during operation is illustrated by arrows. Figure 6A shows the operation in the low calorific design point, with high fuel mass flow. The fuel flows through the distribution area 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 in such a way that there is a high pressure loss within the second fuel channels 603 at the low-calorific design point. The pressure loss caused by the design is so high that a proportion, for example between 90% and 30%, of the fuel flows into the mixing chamber 608 via the first fuel channels 602, the fuel at the first fuel ports 614 having a speed of z. B. 10% to 30% of the air flow at the air ports 610 has. The rotation of the swirl flow is thus driven by the high fuel mass flows. The other portion of the fuel, e.g. B. 10% to 70%, flows via the second fuel channels 603.

In the high calorific design point, with the low fuel mass flow, the pressure difference across the second fuel channels 603 together with a blocking effect of the air flow at the first fuel ports 614 that the fuel mass flow is preferred, e.g. B. (almost) completely, via the second fuel channels 603 with the second fuel ports 616 flows. The swirling flow of the air entrains the fuel flowing into the mixing chamber 608 and accelerates it.

In both the low-calorific and the high-calorific design point, the air velocities are such that flame stabilization is achieved by the swirl flow. The proportion of fuel flow over the second fuel channels 603 varies between z. B. 10% to 70% and (nearly) 100% between the low caloric and the high caloric design point. In this way, stable, pressure-loss-optimized (and thus more efficient) operation can be achieved with the same geometry with low, medium and high-calorific fuels.

Due to the configuration of the burner system 1 and the method according to the invention, the burner system 1 can be operated stably and reliably with both low-calorific and high-calorific fuels and variants in between. Since the adjusted flow through the air/fuel supply arrangements is set due to the changing pressure conditions with the changing calorific value or Wobbe index without changing the (burner head) geometry, no adjustment or regulation via a control or regulating device is advantageously required.

Claims (17)

1. Burner system (1) for generating hot gas in a gas turbine plant, having a combustion chamber (6) which comprises a combustion space (24, 26) oriented along a longitudinal axis (L), and having a burner head (4) which has at least one oxidizer/fuel supply arrangement (50) for supplying oxidizer and fuel into the combustion chamber (6) as fresh gas components, comprising

   - one flow path in each case for fuel and oxidizer for supplying them into the combustion space (24, 26), wherein the flow paths upstream of a mixing space (508) each having separate flow portions for separately guiding the fresh gas components, and the flow paths are combined in the mixing space (508), and

   - at least one first supply opening for supplying fuel into the mixing space (508), wherein the oxidizer/fuel supply arrangement (50) 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 (24, 26) can be supplied into a flow portion with the other fresh gas component, wherein 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, in such a way that the velocities at the first supply opening and/or at the further supply opening deviate from each other at most by a factor of 2, in particular at most by a factor of 1.5, preferably at most by a factor of 1.2, between a low-calorific design point and a high-calorific design point, wherein

   - the low-calorific design point corresponds to a design operating point with a low-calorific design fuel, the mass-specific calorific value of which is approximately 5 MJ/kg, and the high-calorific design point corresponds to a design operating point with a high-calorific design fuel, the mass-specific calorific value of which is barely 50 MJ/kg,

   - the thermal outputs of the two design points correspond to each other, and

   - the further supply opening is formed by at least one bypass opening (528), wherein the bypass opening (528) is formed upstream of a fuel opening (510) of a fuel channel (502) in a wall (501) of same, and wherein the further flow portion forms a flow connection between the flow paths of the oxidizer and the fuel.
2. Burner system (1) for generating hot gas in a gas turbine plant, having a combustion chamber (6) which comprises a combustion space (24, 26) oriented along a longitudinal axis (L), and having a burner head (4) which has at least one oxidizer/fuel supply arrangement (60) for supplying oxidizer and fuel into the combustion chamber (6) as fresh gas components, comprising

   - one flow path in each case for fuel and oxidizer for supplying them into the combustion space (24, 26), wherein the flow paths upstream of a mixing space (608) each having separate flow portions for separately guiding the fresh gas components, and the flow paths are combined in the mixing space (608), and

   - at least one first supply opening for supplying fuel into the mixing space (608), wherein the first supply opening is formed by a first fuel opening (614), wherein the oxidizer/fuel supply arrangement (60) 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 (24, 26) can be supplied into a flow portion with the other fresh gas component, wherein 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, in such a way that the velocities at the first supply opening and/or at the further supply opening deviate from each other at most by a factor of 2, in particular at most by a factor of 1.5, preferably at most by a factor of 1.2, between a low-calorific design point and a high-calorific design point, wherein

   - the low-calorific design point corresponds to a design operating point with a low-calorific design fuel, the mass-specific calorific value of which is approximately 5 MJ/kg, and the high-calorific design point corresponds to a design operating point with a high-calorific design fuel, the mass-specific calorific value of which is barely 50 MJ/kg,

   - the thermal outputs of the two design points correspond to each other,

   - the mixing space (608) is arranged centrally on the longitudinal axis (L) and is symmetrical with respect to said axis, and is delimited on the bottom by a bottom wall (626), which is preferably oriented perpendicularly to the longitudinal axis (L), and peripherally by a wall (609), and opens downstream into the combustion space (26) with an outlet (612), wherein the fresh gas components can be supplied to the mixing space (608) in such a way that a swirling flow having a tangential directional component is generated, and

   - the further supply opening is formed by a second fuel opening (616) into the mixing space (608), wherein the further flow portion comprises a second fuel channel (603) which is oriented with an axial directional 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) having an outlet (512) for opening into the combustion chamber (6), an outflow portion (516) of the oxidizer channel (504) being oriented along a central axis (M) which, substantially axially, extends in parallel with the longitudinal axis (L).
4. Burner system (1) according to claim 3,
   characterized in that
   the oxidizer/fuel supply arrangement (50) has the fuel channel (502) which is delimited by the wall (501), which channel is designed to extend in parallel with, in particular coaxially to, the oxidizer channel (504), at least with one end portion (503) in the oxidizer channel (504), and the fuel opening (510) of which opens within the oxidizer channel (504) or at the outlet (512) thereof, the fuel opening (510) forming 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 having a diameter (d₃), which is reduced compared to the flow cross section, in particular having a diameter (d₂), of the fuel channel (502) extending upstream, or

   in that the fuel opening (510) has a flow cross section, in particular having a diameter (d₃), which corresponds to the flow cross section, in particular having a diameter (d₂), of the fuel channel (502) extending upstream.
6. Burner system (1) according to any of claims 1 or 3-5,
   characterized in that
   the flow cross section of the fuel opening (510) is 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 (510) is between +/- 50 %, preferably between +/- 20 %, of the velocity of the fresh gas mixture at the outlet (512) into the combustion space (24), the portion flowing through the bypass opening (528) being equal to zero.
7. Burner system (1) according to any of the preceding claims,
   characterized in that
   a plurality of further flow portions are present, which are in particular symmetrical to one another, e.g. are arranged rotationally symmetrically about the central axis (M) and axially at the same height.
8. Burner system (1) according to any of claims 1 or 3-7,
   characterized in that

   the bypass opening (528) is arranged axially inside the oxidizer channel (504) downstream of an inflow portion (514) of the oxidizer channel (504), which preferably has such an axial length that inlet effects of the oxidizer flow in the case of inflow into the oxidizer channel (504), in particular local flow separations, have substantially subsided at the bypass opening (528), and/or

   in that the bypass opening (528) is arranged axially within the oxidizer channel (504) upstream of an outflow portion (516) of the end portion (503), which preferably has such an axial length that inlet effects in the case of the one fresh gas component flowing into the other have substantially subsided by the fuel opening (510).
9. Burner system (1) according to any of claims 1 or 3-8,
   characterized in that
   the further flow portion comprises a bypass channel (526) in the wall (501), which channel extends 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 (α) is between 0° and 90°, in particular between 10° and 60°, e.g. is between 15° and 45°, or

    in that the angle (α) is between 90° and 180°, in particular between 110° and 170°, e.g. is between 135° and 165°.
11. Burner system (1) according to any of claims 3 to 10,
    characterized in that

    the oxidizer channel (504) comprises a first portion (520) in the axial course thereof and a second portion (522) downstream of the first portion (520), a reduction in cross section being arranged between the two portions (520, 522), and

    in that the fuel opening (510) is arranged axially at, within or downstream of the reduction in cross section.
12. Burner system (1) according to either claim 2 or claim 7,
    characterized in that

    the oxidizer/fuel supply arrangement (60) has at least one oxidizer channel (604) which opens into the mixing space (608) on the periphery and which is oriented with a tangential directional component with respect to the longitudinal axis (L), the oxidizer channel (604) being assigned to the separate flow portion of the oxidizer, and/or

    in that a distribution region (40) for fuel is associated with the oxidizer/fuel supply arrangement (50, 60), which region is in particular arranged symmetrically with respect to, e.g. centrally on, the longitudinal axis (L) and adjacent to the rear of the bottom wall (626).
13. Burner system (1) according to any of claims 2, 7 or 12,
    characterized in that
    the first supply opening is formed by at least one first fuel opening (614), which opens into the mixing space (608) on the periphery and which forms the downstream end of a first fuel channel (602), an end portion (601) of the fuel channel (602) extending with a tangential directional component with respect to the longitudinal axis.
14. Burner system (1) according to claim 13,
    characterized in that

    an oxidizer opening (610) of the oxidizer channel (604) and the first fuel opening (614) are arranged axially offset from one another, the axial lower edge of the oxidizer opening (610) being arranged upstream of the axial lower edge of the fuel opening (614), and/or

    in that the overall flow cross section of the first fuel opening (614) is designed in such a way that the inflow velocity of the fuel into the mixing space (608) 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 (610).
15. Burner system (1) according to any of claims 2, 7 or 12-14,
    characterized in that

    the second fuel opening (616) is arranged in the mixing space (608) at a location (B) at which there is a lower pressure at a high-calorific design point than at a location (A) of the first fuel opening (614), and/or

    in that the second fuel channel (603) forms a flow connection between the distribution region (40) and the mixing space (608) and extends through the bottom wall (626), the second fuel opening (616) in particular being positioned so as to be axially level with the surface of the bottom wall (626) on the mixing space side.
16. Burner system (1) according to any of claims 2, 7 or 12-15,
    characterized in that

    the total flow cross section(s) of the further flow portion(s) is/are designed in such a way that, at the high-calorific design point, a portion of at least 70 %, preferably at least 90 %, e.g. e.g. 100 % of the fuel flows through the second fuel channel (603), and/or,

    at the low-calorific design point, a portion of at least 30 %, preferably at least 70 %, e.g. at least 90 % of the fuel flows through the first fuel channel (602).
17. Method for generating hot gas in a gas turbine plant with a burner system (1) according to any of the preceding claims, in which oxidizer and fuel are supplied to a combustion space (24, 26) of a combustion chamber (6) as fresh gas components via at least one oxidizer/fuel supply arrangement (50, 60) of a burner head (4), the fresh gas components each flowing via a flow path having separate flow portions within the oxidizer/fuel supply arrangement (50, 60) into a mixing space (508, 608) in which the flow paths of the fresh gas components are combined, the fuel flow to the opening into the mixing space (508, 608) passing a first supply opening,
    characterized in that
    one of the fresh gas component flows within the burner head (4), in particular within the oxidizer/fuel supply arrangement (50, 60), can be divided into at least two portions, one of the portions within the oxidizer/fuel supply arrangement (50, 60) flowing via at least one further flow portion having a further supply opening, and, in the case of a fixed geometry, the portion of the fresh gas component that flows via the further flow portion changing with the calorific value of the fuel, as a result of a changing pressure ratio, in such a way that the velocities at the first supply opening and/or at the further supply opening deviate from each other at most by a factor of 2, in particular at most by a factor of 1.5, preferably at most by a factor of 1.2, between a low-calorific design point and a high-calorific design point.

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