EP1504222A1

EP1504222A1 - Premix burner

Info

Publication number: EP1504222A1
Application number: EP03732592A
Authority: EP
Inventors: Timothy Dr. Griffin; Frank Reiss; Dieter Winkler
Original assignee: Alstom Technology AG
Current assignee: General Electric Technology GmbH
Priority date: 2002-05-16
Filing date: 2003-05-14
Publication date: 2005-02-09
Anticipated expiration: 2023-05-14
Also published as: WO2003098110A1; DE50307654D1; US7013648B2; EP1504222B1; US20050115244A1; AU2003238524A1

Abstract

The invention relates to a premix burner comprising a turbulence generator (7) for a combustion air flow and means for injecting the fuel into the combustion air flow. The turbulence generator (7) comprises one or more combustion air inlets for the combustion air flow entering the burner. The means for injecting fuel into the combustion air flow comprise one or more first fuel feed elements (8) with first fuel outlets (4). The opening diameter of the outlets and/or the injection angle thereof relative to the axial and/or radial direction is configured differently. Alternatively or additionally, some of the first fuel outlets (4) can be arranged in one or several first groups of fuel outlets which are arranged close to each other, such that each of the first groups produce a fuel jet having a large jet cross-section. The inventive burner enables improved premixing of fuel with the combustion air, especially when the fuel is injected into the combustion chamber end of the burner.

Description

premix

Technical application area

The present invention relates to a premix burner for operation in a combustion chamber, preferably in combustion chambers of gas turbines, according to the preamble of claim 1.

A preferred area of use for such a burner is in gas and steam turbine technology.

State of the art

EP 0 321 809 B1 discloses a conical burner consisting of several shells, a so-called double-cone burner, according to the preamble of claim 1. The conical swirl generator, which is composed of several shells, creates a closed swirl flow in a swirl chamber, which becomes unstable due to the swirl increasing in the direction of the combustion chamber and changes into an annular swirl flow with backflow in the center. The shells of the swirl generator are composed in such a way that tangential air inlet slots for combustion air are formed along the burner axis. At the leading edge of the conical shells at these air inlet slots, feeds for the premix gas, ie the gaseous fuel, are provided, which have outlet openings for the premix gas distributed along the direction of the burner axis. The gas is injected through the outlet openings or bores transversely to the air inlet gap. This injection leads in connection with the in Swirl chamber produced swirl of the combustion air / fuel gas flow for thorough mixing of the premixed fuel with the combustion air. With these premix burners, thorough mixing is the prerequisite for low NO values in the combustion process.

To further improve such a burner, a burner for a heat generator is known from EP 0 780 629 A2, which has an additional mixing section for further mixing of fuel and combustion air after the swirl generator. This mixing section can be designed, for example, as a downstream pipe section into which the flow emerging from the swirl generator is transferred without any appreciable flow losses. The degree of mixing can be further increased by the additional mixing section and thus the pollutant emissions can be reduced.

WO 93/17279 shows another known premix burner in which a cylindrical swirl generator with a conical inner body is used. In this burner, the premix gas is also injected into the swirl chamber via feeds with corresponding outlet openings, which are arranged along the axially extending air inlet slots. The burner also has a central supply for fuel gas in the conical inner body, which can be injected into the swirl chamber for piloting near the burner outlet. The additional pilot stage is used to start the burner and to expand the operating range. In the so-called pilot mode, which Incidentally, for other types of premix burner, which is part of the general state of the art, the fuel is introduced - for example in the form of a gas jet injected along the burner axis - in such a way that it does not mix with the combustion air beforehand. A diffusion flame is thus generated which, on the one hand, leads to higher pollutant emissions, but on the other hand also has a much wider stable operating range.

A premix burner is known from EP 1 070 915 A1, in which the fuel gas supply is mechanically decoupled from the swirl generator. As a result, stresses due to thermal expansions are avoided when only slightly preheated fuel gases are used. The swirl generator is here provided with a series of openings through which fuel lines mechanically decoupled from the swirl generator for gas premixing operation protrude into the interior of the swirl generator and feed gaseous fuel to the swirled flow of the combustion air there.

These known premix burners of the prior art are so-called spin-stabilized premix burners in which a fuel mass flow is distributed as homogeneously as possible prior to combustion in a combustion air mass flow. With these types of burners, the combustion air flows in through the tangential air inlet slots in the swirl generators. The

Fuel, particularly natural gas, is typically injected along the air inlet slots. In addition to natural gas and liquid fuel, mostly diesel oil or Oil # 2, gas turbines also use synthetically produced gases, so-called Mbtu and Lbtu gases, for combustion. These synthesis gases are produced by the gasification of coal or oil residues. They are characterized by the fact that they largely consist of H ₂ and CO. In addition, there is a smaller proportion of inert gases, such as N ₂ or C0 ₂ .

When synthetic gas is burned, the injection which has been tried and tested for natural gas in the burners of the prior art cannot be maintained due to the high re-ignition risk.

In contrast to the use of natural gas, there are the following special features and requirements for a burner that is to be operated with synthesis gas. Depending on a dilution of the synthesis gas known per se according to the state of the art, synthesis gas requires around four times - in the case of undiluted synthesis gas up to seven times or even more - higher fuel volume flow compared to comparable natural gas burners, so that the burner has the same gas perforation and significantly different Impulse ratios result. Due to the high proportion of hydrogen in the synthesis gas and the associated low ignition temperature and high flame speed of the hydrogen, there is a high tendency of the fuel to react, so that in particular the re-ignition behavior and the dwell time of ignitable fuel-air mixture near the burner must be investigated. Furthermore, a stable and safe combustion of synthesis gases for a sufficiently large range of calorific values must be guaranteed which, depending on the process quality of the gasification and the starting product, e.g. oil residues, has a different composition of the synthesis gas. In order to achieve a premixture during combustion under these conditions and thus achieve the typical low emissions, these synthesis gases are usually diluted with inert gases such as N ₂ or water vapor before combustion. In particular, this reduces the risk of reignition due to the high H ₂ content. The burner must therefore be able to burn synthesis gases of different compositions, in particular different dilutions and, as a result, highly variable fuel volume flow, safely and stably.

It is also an advantage if next to the

Synthesis gas from the burner is also a reserve fuel, a so-called backup fuel can be burned safely. This requirement results in the highly complex integrated gas synthesis and power generation (IGCC, I_ntegrated Gasification Combined Cycle)

Systems that demand high availability. In such a case, the burner should function safely and reliably even in the mixed operation of synthesis gas and backup fuel, for example diesel oil, with the burner operating in the

Mixed operation of a single burner to maximize usable fuel mixture spectrum. Of course, low emissions, typically NO _x <25 vppm and CO <5 vppm, should be guaranteed for the specified and used fuels.

From EP 0610 722 AI a double cone burner is known in which a group of fuel Outlet openings for a synthesis gas are arranged on the swirl generator at an end of the burner on the combustion chamber side distributed over the circumference of the burner. These outlet openings are supplied via a separate fuel line and enable the burner to be operated with undiluted synthesis gas.

However, this injection of the fuel at the end of the burner on the combustion chamber side can result in insufficient mixing of the fuel with the swirl flow of the combustion air, since the fuel remains in the swirl flow for only a short time until the flame stabilization zone (vortex recirculation zone) is reached.

Another problem arises with the aforementioned prior art burners if they are designed for the injection of a fuel with a low to medium calorific value or are operated with such a fuel. Fuels with a low to medium calorific value have to be high

Volume flows are introduced into the swirl flow in order to achieve sufficient heat generation during combustion. Due to the high volume flows of the fuel, however, the swirl flow which forms in the burner is disturbed, so that in extreme cases the recirculation zone stabilizing the flame may fail to appear. Presentation of the invention

Starting from the prior art set out above, the object of the present invention is to provide a premix burner in which the disadvantages of the prior art do not occur and which, particularly when operated with synthesis gas or a fuel with a low to medium calorific value, result in improved mixing with the combustion air guaranteed.

The object is achieved with the burners according to claims 1 and 2. Advantageous configurations of these burners are the subject of the subclaims or can be derived from the following

Take description and the embodiments.

The present burner consists in a known manner of a swirl generator for a combustion air flow and means for injecting fuel into the

Combustion air flow. In this context, injection means the introduction of fuel via an outlet opening, a directed fuel jet of any geometry preferably being generated. The swirl generator has combustion air inlet openings for the combustion air flow which preferably enters the burner tangentially. The means for injecting fuel into the combustion air stream comprise one or more first fuel feeds with first fuel outlet openings. Depending on the structure of the burner, these fuel outlet openings can, for example, extend over the circumference of the burner in one or more planes perpendicular to the Burner longitudinal axis, ie to the axial direction, can be distributed or arranged along the first fuel feeds on the outer shell of the burner or on an inner body in the burner. In the present burner, the first fuel outlet openings are designed such that the opening diameter of these first fuel outlet openings and / or an injection angle of the first fuel outlet openings relative to the axial and / or the radial direction along the first fuel feeds and / or above the The size of the burner varies. In an alternative embodiment, at least some of the first fuel outlet openings are arranged in one or more first groups of fuel outlet openings located close to one another in such a way that each of the first groups has a fuel jet with a fuel jet - relative to a fuel jet formed by a single fuel outlet opening - generated large beam cross-section. Each group then acts equivalent to a fuel outlet opening with a correspondingly larger opening diameter.

The present configuration of the fuel outlet openings extends over the circumference of the burner and / or over the axial extent of the

Burner varying opening diameters and / or axial and / or radial injection angles, an improved mixing of the injected fuel with the combustion air forming the swirl flow is achieved. The different opening diameters and / or injection angles cause a different penetration depth of the fuel into the internal volume or the swirl flow of the burner. The As a result, fuel can be distributed more evenly over the combustion air. Furthermore, the different penetration depth of the fuel jets emerging from the fuel outlet openings leads to less disturbance of the swirl flow, since no continuous fuel wall can build up, as can be the case with high volume flows of the fuel and identically designed fuel outlet openings of the prior art. The swirl flow generated in the burner can be additionally supported by a suitable choice of the injection angle.

In an alternative embodiment of the present burner, in which at least some of the first fuel outlet openings are arranged in individual groups of fuel outlet openings located close to one another, a single fuel jet of a large diameter is formed by the respective fuel outlet openings of a single group, the one has a greater depth of penetration than the fuel jet of a single outlet opening. For this purpose, the fuel outlet openings of the individual groups must be sufficiently close to one another so that they form a common fuel jet, so that each

Group equivalent to a fuel outlet opening with a correspondingly larger opening diameter. This configuration also results in a variation in the penetration depth of the fuel over the circumference and / or the axial extension of the burner due to the greater penetration depth of the common fuel jet, so that there is better mixing of the fuel and combustion air. Of course This alternative design of the burner can also be combined in any way with the design of the fuel outlet openings with different injection angles and opening diameters. The different injection angles can be achieved in a known manner by differently aligning the outlet channels forming the fuel outlet openings in the fuel feed lines.

Preferably, the opening diameter or injection angle alternate along the circumference of the burner or the fuel feeds between at least two values, so that in the circumferential or longitudinal direction of the burner alternately a larger and a smaller injection angle or a larger and a smaller opening diameter in the same Direction fuel outlet openings are present. With more than two different values of the opening diameter and / or the injection angle, the corresponding variation is preferably carried out by periodically repeating the different opening diameters or injection angles in the circumferential or longitudinal direction of the burner. With a simultaneous variation of the opening diameter and the injection angle relative to the axial direction, a larger opening diameter is selected for a fuel outlet opening with a larger injection angle than for a fuel outlet opening with a smaller injection angle.

With a variation of the injection angle relative to the radial direction, this injection angle becomes the Fuel outlet openings are selected such that fuel jets from different groups of outlet openings emerging from the fuel outlet openings each intersect at different points outside the central longitudinal axis of the burner in the internal volume of the burner.

In the preferred embodiment of the present burner, the first fuel outlet openings are at an end of the burner on the combustion chamber side, i. H. at the burner outlet, distributed over the circumference of the burner. In this case, the one or more first fuel feeds with the first fuel outlet openings are preferably mechanically decoupled from the swirl generator.

The geometry of the swirl generator and of any swirl space that may be present can be selected in different ways in the present burner and in particular have the geometries known from the prior art. The preferably distribution of the first fuel outlet openings exclusively at the end of the burner or swirl space on the combustion chamber side over the circumference of the burner reliably prevents backfiring of the syngas injected. Mixing with the combustion air emerging from the burner is nevertheless sufficiently ensured. Synthesis gas with a high hydrogen content (45 vol%) can be burned undiluted (lower heating value Hu ~ 14000 kJ / kg).

Of course, the burner can also be operated with synthesis gas with a different hydrogen content, for example with H ₂ ^~ 33%. The burner in this embodiment therefore enables safe and stable combustion of both undiluted and diluted synthesis gas. This guarantees a high degree of flexibility when using a gas turbine equipped with burners according to the invention in an IGCC process. A correspondingly cross-sectional configuration of the first fuel supply (s) enables high volume flows, up to a factor of 7 compared to the supply of natural gas in known burners of the prior art, to be safely conducted to the injection point at the burner outlet.

In the present burner, the one or more first fuel feeds with the associated first fuel outlet openings are preferably mechanically and thermally decoupled from the swirl generator or the burner shells which form the swirl generator and are significantly warmer during operation. In this way, both components can perform thermal expansions and in particular differential expansions independently of one another and without mutual interference. As a result, the thermal stresses between the comparatively cold first fuel feeds, hereinafter also referred to as gas channels, and the warmer burner shells are avoided or at least significantly reduced. In one embodiment of the present burner, as is explained in more detail in the exemplary embodiments, the injection region for the synthesis gas in the burner shells is completely cut out. The first gas channel is anchored directly in this section of the burner bowls. This means that the gas channel and burner trays are thermal and mechanically decoupled from each other and the constructive problem at the connection points of the cold gas duct and the warm burner bowl is solved. Earlier constructions like that of EP 0610 722 AI showed especially when connecting relatively cold

Gas duct to hot burner bowl Problems, e.g. cracks due to the high stress concentration at these connection points. With the decoupled solution and the presented design, the required burner life is achieved.

The decoupling of individual fuel lances from the burner shells is already known from EP 1 070 915. In an advantageous embodiment of the present burner, however, this mechanical decoupling is realized for the first time with integral gas channels with homogeneous gas introduction. Compared to the gas injection known from EP 1 070 950, this homogeneous gas injection impresses with a substantially more uniform distribution of the fuel in the combustion air, and thus, especially when using Lbtu and Mbtu fuels, with superior emission behavior with good flame stability. A costly special thermal insulation of the gas duct from the hot burner shell - for example due to the gas duct inserts known per se to the person skilled in the art - is not necessary.

In the case of a burner in particular, in which the first fuel outlet openings are arranged at the end of the burner on the combustion chamber side over the circumference of the burner, the present invention can be used

Varying the injection angle or the injection depth can achieve a significantly improved mixing of the fuel with the combustion air. Of course, however, an improved mixing effect as well as less disturbance of the swirl flow can also be achieved in burners in which the first fuel feeds with the first fuel outlet openings are arranged in the longitudinal direction of the burner along its outer shell or outer shells.

In a further embodiment, the

In addition to the first fuel feed (s), the burner also has one or more second fuel feeds with a group of second fuel outlet openings arranged essentially along the direction of the burner axis on the swirl body. Alternatively or in combination, a fuel lance arranged essentially on the burner axis for the injection of liquid fuel or of pilot gas for diffusion combustion can also be provided, which projects into the swirl space in the axial direction. The arrangement and

Design of these additional fuel feeds can be based, for example, on the known premix burner technology according to EP 321 809 or also other types, such as according to EP 780 629 or WO 93/17279. Such burner geometries can be realized with the features according to the invention for the design and arrangement of the first fuel outlet openings.

Through this embodiment of the present

With a burner with one or more additional fuel feeds, a multifunctional burner is obtained that can safely and widely different fuels burns stably. The burner can in particular handle the stable and safe combustion of Mbtu synthesis gases (minimum content of H ₂ = 10 vol%) with heating values (lower heating value Hu or Lower Heating Value LHV) of 3500 - 18000 kJ / kg, in particular 6000 to 15000 kJ / kg , preferably from 6500 to 14500 kJ / kg or from 7000 to 14000 kg / kJ. In addition to the safe and stable combustion of undiluted and diluted synthesis gas with appropriate arrangement of the first fuel outlet openings at the end of the burner on the combustion chamber side, liquid fuel, for example diesel oil, can also be used as a reserve fuel. The fuels used can differ significantly in their calorific value, for example in the case of diesel oil with a calorific value of Hu = 42000 kJ / kg and

Synthesis gas with a calorific value of 3500 - 18000 kJ / kg, in particular 6000 to 15000 kJ / kg, preferably from 6500 to 14500 kJ / kg or from 7000 to 14000 kg / kJ.

The use of natural gas as an additional fuel is also possible. Natural gas can be injected in the burner head either through the burner lance and / or via the second fuel feeds, which are usually formed by the gas channels arranged lengthways on the air inlet slots on the swirl generator or swirl body

Those skilled in the art are familiar, for example, from EP 321 809. In this way, the burner can be operated with three different fuels.

For the combustion of synthesis gas, the first fuel feeds are still structurally adapted to the fuel volume flow, which is up to 7 times greater, and in particular provide the necessary ones Flow cross-sections available. They have a multiple cross-section compared to the natural gas feeds.

When using oil as fuel, the injection of the oil or an oil-water emulsion known from the prior art is maintained via a burner lance. Due to various boundary conditions, such as the integration of the gas turbine in the IGCC process or fixed burner groups that are to be retained, gas turbines that burn synthesis gas have to ensure the mixed operation of pilot fuel and synthesis gas. The burner described here also works stably and safely in mixed operation of diesel oil and synthesis gas in various mixing ratios. It can be operated safely in mixed operation for longer periods. The gas turbine thus achieves further flexibility and can switch from one fuel to another during operation. The possible mixed operation represents a significant operational advantage.

Brief description of the drawings

The present invention is briefly explained again below without restricting the general inventive concept on the basis of exemplary embodiments in conjunction with the figures. Here show:

1 schematically shows some of the parameters of the outlet openings influenced in the present burner;

2 is a sectional view of an embodiment of the present burner; 3 shows a sectional view through the plane BB of the burner of FIG. 2;

4 shows an exemplary representation of different injection angles relative to the axial direction;

5 shows an example of the formation of individual groups of outlet openings for generating a fuel jet with a large jet diameter;

Fig. 6 shows an example of the variation of

Injection angle relative to the radial direction;

7 shows a highly schematic example of a burner arranged along the longitudinal extension of the burner

Fuel outlet openings and examples of the design of the fuel outlet openings;

8 shows an example of a configuration of the burner with a conical inner body; and

9 shows an example of a further possible embodiment of the burner.

Ways of Carrying Out the Invention

For illustration, FIG. 1 shows different parameters in the design of fuel outlet openings, which play a role in the implementation of the present burner. In the figure, part of a) is schematically shown in partial illustration a)

Brenners shown in sectional view, in which the Burner bowl 1, a central burner longitudinal axis 2 and a front panel 3 provided on the combustion chamber end of the burner can be seen. In this example, fuel outlet openings 4 are arranged over the circumference of the burner bowl 1, which the

Have opening diameter d and a uniform distance a to the front panel 3. In this example, the burner bowl 1 has an inclination of = 11 ° to the axial direction predetermined by the burner longitudinal axis 2. The fuel outlet openings 4 are designed as outlet channels, the channel axis 5 of which extends at a certain angle to the axial and radial direction of the burner. The course of the channel is illustrated in this figure by the lines drawn out to the side with the opening cross-section hatched therein. The direction of the outlet channel axis 5 to the axial and radial direction of the burner determines the direction of injection of the fuel into the interior of the burner. The speed vector c of the injection and its corresponding components in the axial direction (u) and in the radial direction (v) can be seen in the figure. The injection angle relative to the axial direction is denoted by ψ, the angle relative to the perpendicular to the burner wall or burner shell 1 by ß. Typical values for the angle β are 20 °, 30 ° or 40 °.

In part figure b) a plan view of a burner according to part figure a) is also shown. This figure does not show the one in partial illustration a)

To recognize velocity component w of the fuel jet injected through the fuel inlet opening 4. This speed component has one Angle d relative to the radial direction of the burner. In the present example, the injection takes place in the same direction as the swirl direction 6 of the combustion air entering the burner, as can be seen from the partial illustration.

In the present burner, the parameters illustrated in FIG. H. the injection angle ψ relative to the axial direction, the injection angle d relative to the radial direction and the opening diameter d of the fuel outlet openings in the circumferential direction of the burner and / or along the fuel feed lines, so that different groups of fuel outlet openings have different injection angles d or ψ and / or have different opening diameters d.

The opening diameter d, the distance between the individual outlet openings, the pulse ratio between fuel and combustion air as well as the injection direction have an influence on the depth of penetration of the fuel jet into the burner or the swirl flow within the burner. This penetration depth is proportional to J ^a xdx sinψ, where a and b are positive exponents, J is the pulse ratio between fuel and combustion air and d is the diameter of the fuel outlet openings.

From this context it can be seen that a

Increasing the fuel injection pulse has a significant impact on the depth of penetration. However, the fuel available in a fuel system limited fabric printing. The opening diameter of the fuel outlet openings also has an influence on the depth of penetration, but is also limited. In particular, an opening diameter that is too large can adversely affect the reliability of the fuel system during part-load operation and during fuel oil operation. This applies in particular to the thermoacoustic stability of the overall system.

FIG. 2 shows an example of a structure of a burner with first fuel feeds and fuel outlet openings, which can be designed in accordance with the present invention. In this embodiment of a burner, which is particularly suitable for the injection of synthesis gas, first fuel outlet openings 4 are arranged radially at the end of the burner outlet, ie at the end of the inner space 12 of the burner forming the swirl space, distributed in a row over the circumference of the burner. This injection at the burner outlet also enables the hydrogen-rich synthesis gas to be burned undiluted. The figure shows the burner shells 1 which, in this example, form the swirl generator 7 due to their cone-shaped configuration. Outside of this swirl generator 7, a gas supply element 13 is arranged, which radially surrounds the swirl generator 7 and forms the first fuel supply (s) 8 for the supply of synthesis gas. The first fuel outlet openings 4 for the synthesis gas are arranged at the end of this gas supply element 13 on the combustion chamber side. These outlet openings 4 form outlet channels which specify the injection direction of the synthesis gas. The one indicated in this example Injection angle ψ relative to the axial direction and / or the diameter d of these channels or openings 4 vary in the present burner, as can be seen, for example, from the following FIGS. 4-6.

In the present example, a total of 12 first fuel outlet openings 4 are arranged next to one another evenly distributed over the circumference of the burner, which are designated by the Roman numerals I - XII. The odd-numbered outlet openings 4 here have an injection angle ψ relative to the axial direction of approximately 50 ° (60 ° to the burner shell), while the odd-numbered outlet openings 4 have an injection angle of approximately 40 ° to the axial direction (50 ° to the burner shell).

The comparatively cold fuel supply channels 8 for injection of the synthesis gas and the burner shells 1, which in principle are significantly warmer, are thermally and mechanically decoupled from one another in this example. This significantly reduces the thermal stresses. The connection between the gas supply element 13 and the swirl generator 7 takes place via tabs 10 and 11 provided on both components, which are connected to one another. In this way, minimal thermal stresses are achieved. In the figure, an opening or a circumferential gap 9 can also be seen on the swirl generator 7, which is necessary to enable a connection between the outlet openings 4 of the gas supply element 13 and the swirl chamber 12. In the present example, the injection area for the fuel in the burner trays is completely cut out. The gas supply element 13 is anchored directly in this section of the burner shells 1 and the swirl generator 7. This solves the voltage problem at the junctures of the cold gas supply element 13 and the warm burner bowl. The swirl generator 7 itself is preferably formed from at least two partial shells with tangential air inlet slots, as is known, for example, from EP 0 321 809 B1.

Figure 3 shows the burner of Figure 2 again along the section line B-B. In this figure, the two partial shells of the swirl generator 7 with the tangential air inlet slots 14 and the fuel feeds 8 of the gas feed element 13 can be clearly seen. The 12 fuel outlet openings 4 are again indicated in each of these fuel feeds 8. The burner is enclosed by a housing 15. The gas supply element 13 can be designed on the one hand as an annular supply slot for forming a single fuel supply channel 8 or can also be divided into separate fuel supply channels. Of course, it is also possible to lead individual feed lines as fuel feed channels 8 to the outlet openings 4.

The fuel supply channels 8 are adapted for the supply of synthesis gas to the up to seven times larger fuel volume flow compared to conventional fuels and in particular provide the necessary large flow cross sections. Of course, additional gas injection ducts can also be arranged along the air inlet slots 14 in such a burner, as is the case with the known burner geometries of the prior art, for example the already mentioned EP 0 321 809 B1. Conventional fuel can be injected into the inner volume 12 in addition or as an alternative to the synthesis gas via these additional fuel supply channels.

FIG. 4 schematically shows the injection direction of the fuel outlet openings 4 of a burner like that of FIGS. 2 and 3 according to an embodiment of the present invention. In partial view a), one half of the burner can be seen in plan view with the fuel outlet openings 4 arranged distributed over the circumference. The direction of injection of the twelve outlet openings 4 shown relative to the radial direction is d = 0 °, d. H. that all fuel jets emerging from the outlet openings are aligned with the central longitudinal axis of the burner, as is illustrated by the lines shown in the figure.

In part b) is the injection angle alternating between two values in this example? relative to the axial direction of the burner recognizing the values? = 40 ° and? = 50 °. All even fuel outlets

(II / IV / VI / VIII / X / XII) have an injection angle of 50 °, all odd-numbered outlet openings 4 (I / III / V / VII / IX / XI) have a smaller injection angle angle of? = 40 ° on. Because of this variation of the injection angle? The local mixing of the injected fuel with the combustion air is improved over the circumference of the burner due to the different penetration depth of the fuel jets. The overlap of the individual fuel jets is reduced, so that the fuel is better distributed within the swirl flow.

An improved distribution can also be achieved by varying the opening diameter d of the individual fuel outlet openings 4. For example, these can alternate between two values in the same way as the injection angle in FIG. 4, so that every second outlet opening has the same opening diameter. These different opening diameters also change the penetration depth of the fuel jet, so that better distribution and mixing of the fuel with the combustion air is achieved. Of course, the variation of the opening diameter can be combined with the variation of the injection angle at any time. Here, a larger opening diameter is preferably combined with a larger injection angle.

FIG. 5 shows a further embodiment of the injection in a burner according to the present invention. This figure also shows schematically a half of a burner according to FIGS. 2 and 3 in plan view, nine in this example

Outlet openings 4 can be seen. In this example, three of these outlet openings 4 are arranged close to one another, so that over the entire Extent of the burner a total of 6 groups of outlet openings 4 are formed, three of which are shown in the figure. As a result of this grouping of the outlet openings 4, the individual jets initially emerging from the outlet openings 4 of a group form an overall jet which, owing to this combination, has a large jet diameter with a greater penetration depth. This grouping also allows the depth of penetration of the fuel into the interior 12 of the burner or the swirl flow to be locally increased.

In FIG. 5, different injection angles d of the individual groups of outlet openings relative to the radial direction are additionally selected, which intersect at a point 16 outside the longitudinal axis 2 of the burner.

Of course, in addition to these groups of fuel outlet openings, further, non-grouped outlet openings can also be provided, via which fuel jets with a smaller jet diameter are additionally injected. A combination with different injection angles? Relative to the axial direction and / or different opening diameters of the individual fuel outlet openings is of course possible. For example, grouped outlet openings can have larger opening diameters than ungrouped outlet openings, or the opening diameters of the outlet openings can vary from group to group. FIG. 6 shows another example of fuel injection in a burner according to the present invention. In this example, the injection angle d varies relative to the radial direction of the burner over the circumference of the burner, so that the

Cut the injection directions at a point 16 far outside the longitudinal axis 2 of the burner. If the fuel is injected in the same direction as the direction of the swirl of the combustion air which is formed in the inner volume 12, this results in a greater depth of penetration than in the case of injection in opposite directions. A better distribution of the fuel within the swirl flow can thus also be achieved via this injection angle d. In addition, the strength of this flow can be increased by the injection in the same direction to the direction of the swirl flow, so that the flame stabilization process can be supported. This variation of the injection angle d relative to the radial direction can also be combined with the examples explained above. Of course, it is also possible to design individual groups of fuel outlet openings with regard to their injection angle d such that their injection directions form different intersection points 16 within the internal volume of the burner.

It goes without saying that the number of fuel outlet openings 4 shown in the preceding exemplary embodiments can be chosen as desired, depending on the requirement. Likewise, of course, several rows of fuel outlet openings 4 can also be provided, which can be designed according to the preceding examples. Even when the fuel is injected via fuel outlet openings, which are arranged in the axial direction of the burner shells, they can be formed in accordance with the preceding exemplary embodiments. This can be seen by way of example from FIG. 7, which shows in part a) a known burner geometry with the swirl generator 7 and the fuel feeds 8 arranged on the swirl generator 7 with corresponding fuel outlet openings 4. The fuel outlet openings 4 of the individual fuel feeds 8 can, according to partial illustration b), be designed, for example, with different opening diameters in order to achieve different penetration depths. In a further embodiment, the channel axes of the outlet channels of these outlet openings 4 can form different angles both to the radial and to the axial direction of the burner. With such configurations, the same effects can be achieved as explained in connection with the preceding figures.

Although the invention was primarily shown on a double-cone burner of a type known from EP 0 321 809 B1, the person skilled in the art readily recognizes the applicability of the invention to other types of burner and swirl generator geometries, for example as described in EP 780 629 or WO 93/17279 are known. Modifications of these burner geometries are of course also possible, as long as the configuration of the fuel outlet openings according to the invention can be realized with these types of burners. For example, FIG. 8 shows an example of a swirl generator 7 with a purely cylindrical swirl body 17, in which a conical inner body 18 is inserted. In this example, the outlet openings 4 for synthesis gas are arranged distributed over the circumference of the burner at the combustion chamber end of the swirl chamber 12. The fuel supply channels 8 are not shown in this illustration. Here, too, additional gas outlet openings for natural gas, including the supply lines required for this, can additionally be provided at the tangential air inlet slots (not shown).

A further example of a burner, in which the swirl generator 7 is designed as a swirl grille, via which incoming combustion air 19 is swirled, is shown schematically in FIG. 9. Additional fuel for premix loading can be introduced into the combustion air 19 via the feed lines 20 leading to outlet openings in the area of the swirl generator 7. A pilot fuel or a liquid fuel is supplied via a nozzle 21 projecting centrally into the inner volume 12. In this burner, too, the outlet openings 4 for the synthesis gas are arranged distributed over the circumference of the burner at the end of the inner volume 12 on the combustion chamber side and are supplied with synthesis gas via the fuel supply channels 8. With both burner geometries of FIGS. 8 and 9, the same configurations can be seen

Realize outlet openings 4, as in the burner shown in Figures 2 and 3. LIST OF REFERENCE NUMBERS

Burner bowl Burner longitudinal axis Front panel first fuel outlet opening Outlet channel axis Swirl direction Swirl generator First fuel supply Opening slot in the swirl generator Tabs on the swirl generator Tabs on the gas supply element Internal volume (swirl chamber) Gas supply element Air inlet slots Housing Intersection of swirl body Internal body Combustion air supply lines Nozzle

Claims

claims

1. premix burner, essentially consisting of a swirl generator (7) for a combustion air flow — and means for injecting fuel into the combustion air flow, the swirl generator (7) having one or more combustion air inlet openings for the combustion air flow entering the burner and the means one or more first for injecting fuel into the combustion air flow

Fuel supply lines (8) with first fuel outlet openings (4), characterized in that the first fuel outlet openings (4) are designed such that the opening diameter of the first fuel outlet openings (4) and / or an injection angle of the first fuel - Outlet openings (4) vary relative to the axial and / or radial direction along the fuel feeds (8) and / or over the circumference of the burner.

2. Burner, consisting essentially of one

Swirl generator (7) for a combustion air flow and means for injecting fuel into the

Combustion air flow, the swirl generator (7) having one or more combustion air inlet openings for the combustion air flow entering the burner and the means for injecting fuel into the combustion air flow or comprise a plurality of first fuel inlets (8) with first fuel outlet openings (4), characterized in that at least some of the first fuel outlet openings (4) are arranged in one or more first groups of fuel outlet openings (4) which are close to one another, such that each of the first groups generates a fuel jet with a large jet cross section.

3. Burner according to claim 1, characterized in that at least some of the first fuel outlet openings (4) are arranged in one or more first groups of fuel outlet openings (4) located close to one another, such that each of the first groups has a fuel beam with a large beam cross section.

4. Burner according to one of claims 2 or 3, characterized in that at least some of the first groups of first fuel outlet openings (4) differ by different opening diameters of the respective fuel outlet openings.

5. Burner according to one of claims 2 to 4, characterized in that remaining, not arranged in first groups first fuel outlet openings (4) have a smaller opening diameter than that in one or more first groups arranged first fuel outlet openings (4).

Burner according to one of the preceding claims, characterized in that the injection angle of the first fuel outlet openings (4) relative to the axial direction alternates over the circumference between at least two values.

7. Burner according to one of the preceding claims, characterized in that the opening diameter of the first fuel outlet openings (4) alternates over the circumference between at least two values.

8. Burner according to one of the preceding claims, characterized in that first fuel outlet openings (4) with a larger injection angle relative to the axial direction have a larger opening diameter than first fuel outlet openings (4) with a smaller injection angle.

9. Burner according to one of the preceding claims, characterized in that the injection angle relative to the radial direction is selected such that at the first fuel outlet openings (4) emerging fuel jets of different second groups of first fuel outlet openings (4) each in different points (16) cut outside a central burner longitudinal axis (2).

10. Burner according to one of the preceding claims, characterized in that the first fuel outlet openings (4) are arranged distributed over the circumference of the burner at an end of the burner on the combustion chamber side.

11. Burner according to claim 10, characterized in that the first fuel outlet openings (4) are arranged in a row.

12. Burner according to one of the preceding claims, characterized in that the one or more first fuel feeds (8) are mechanically decoupled from the swirl generator (7).

13. Burner according to claim 12, characterized in that the one or more first fuel feeds (8) with the first fuel outlet openings (4) a first

Form swirl generator (7) surrounding component (13), the swirl generator (7) having openings (9) at the combustion chamber end for the access of the first outlet openings (4) to an internal volume (12) of the burner.

14. Burner according to claim 13, characterized in that the first component (13) is connected to the swirl generator (7) via connecting straps (10, 11).

15. Burner according to one of the preceding claims, characterized in that the first fuel feed (8) is designed as an annular slot running on the circumference of the swirl generator (7).

16. Burner according to one of claims 1 to 9, characterized in that the one or more first fuel feeds (8) with the first fuel outlet openings (4) are arranged substantially along the axial direction on the swirl generator (7).

17. Burner according to one of claims 1 to 15, characterized in that one or more second fuel feeds with a group of second fuel outlet openings arranged essentially along the axial direction are arranged on the swirl generator (7).

18. Burner according to claim 17, characterized in that the one or more first fuel feeds (8) are designed with a cross section that enables a volume flow that is several times higher than that of the one or more second fuel feeds.

19. Burner according to one of claims 17 or 18, characterized in that an inner body (18) is arranged in an inner volume (12) of the burner, wherein the second fuel outlet openings of at least one second fuel supply distributed substantially along the axial direction on the Inner body (18) are arranged.

20. Burner according to one of claims 17 to 19, characterized in that the second fuel outlet openings are designed such that the opening diameter of the second fuel outlet openings and / or an injection angle of the second fuel outlet openings relative to the axial and / or to the radial direction along the fuel feeds and / or over the circumference of the burner.

21. Burner according to one of claims 17 to 20, characterized in that at least some of the second fuel outlet openings are arranged in one or more third groups of closely spaced fuel outlet openings such that each of the third groups has a large fuel jet Beam cross section generated.

22. Burner according to one of claims 17 to 21, characterized in that means for independent control of the Premixed fuel supply to the first and to the second fuel supply or are provided.

23. Burner according to one of claims 1 to 22, characterized in that the swirl generator (7) is designed as a swirl grid.

24. Burner according to one of claims 1 to 23, characterized in that the combustion air inlet openings are tangential inlet slots (14) extending essentially in the axial direction.

25. A method of operating a burner according to one of claims 17 to 24, characterized in that synthesis gas is supplied via the first fuel supply (s) (8) and natural gas is supplied via the second (n) fuel supply (s).