EP1730448B1 - Multiple burner arrangement for operating a combustion chamber, and method for operating the multiple burner arrangement - Google Patents

Description

Technical area

The invention relates to a multiple burner arrangement with a plurality of trained as Vormischbrennem individual burners, which serve for firing a combustion chamber for a heat engine, preferably for a gas turbine plant, and each having a swirl space, are fed into the Verbrennungszuluft and fuel to form a swirl flow, wherein the swirl flow downstream of the premix burner within the combustion chamber forms a largely stably forming return flow zone, in which a burner flame is formed after ignition of the fuel-air mixture. Likewise, a method for operating such a multiple burner arrangement will be described.

State of the art

Multiple burner arrangements have prevailed not least for reasons of environmental considerations, since the formation of nitrogen oxides in the exhaust gases can be kept low due to low flame temperature with high excess air. In this context, in particular so-called annular combustion chambers have become established which are used for the purpose of driving gas turbine plants and which provide a multiplicity of individual premix burners in a circular arrangement around the rotating components of a gas turbine, whose hot gases are fed directly via a ring-shaped flow channel of the downstream turbine stage.

Such an annular combustion chamber arrangement is for example from the EP 597 138 B1 can be seen, which provides a plurality annularly arranged Vormischbrenner, as for example the EP 387 532 A1 can be removed and are each designed as a double-cone burners, which provide a radially enclosed from two hollow conical bodies torso swirl space whose respective center axes are offset from each other, so that adjacent walls of two cone bodies include tangential slots for the combustion air in their longitudinal extent. Liquid fuel can be fed into the swirl chamber, which widens conically in the axial direction, via a fuel nozzle arranged largely centrally within the swirl space. Likewise, the premix burner can be supplied with gaseous fuel via gas inlet openings distributed along the tangential slots within the wall of both partial cone bodies. Thus, already forms a mixture formation with the Verbrennungszuluft in zones of the inlet slots, wherein along the axially within the swirl space propagating swirl flow forms a homogeneous fuel concentration over the entire cross section of the swirl space. At the burner outlet, a defined dome-shaped backflow zone is created, at the top of which the ignition takes place, forming a burner flame which is spatially stable within the zone.

In the operation of such a gas turbine plant, the fuel supply for each premix burner is usually carried out at startup of the gas turbine and at low load ranges via a so-called pilot stage, depending on the design of the premix burner as a central burner lance, as for example in the DE 196 52 899 A1 is described, or as a directly at the burner outlet in the flow direction in front of the combustion chamber provided pilot gas supply is formed.

In both cases, fuel is added directly into the flow zone required for flame stabilization, but burns for pollutant emissions in an extremely unfavorable mixing ratio under almost stoichiometric conditions. Due to the so-called pilot high emission values with respect to NO ₂ , CO and NO _X , it is therefore especially in Medium and upper load range of the gas turbine plant required to throttle the fuel supply via the respective pilot stage and make the fuel supply in the context of the so-called premix, ie the supply of gaseous fuel along the air inlet slots through the wall of the Teilkegelschalen. After completely shutting off the pilot fuel supply, it is necessary to remove combustible debris from the pilot leads to avoid flashbacks to the pilot stage. For this purpose, technically complicated rinsing procedures are required. In addition, the switching operations are not desirable from Pilotzum premixing or vice versa, as this burner-internal pulsations are excited, which mechanically load heavily depending on the severity of the system components involved in the combustion process.

Such thermoacoustic oscillations moreover preferably also occur in premix mode, i. in the middle and upper load range, through which the forming within the combustion chamber flame stability is greatly impaired.

Normally, in gas turbine fueled ring combustors, all premix burners are supplied with gaseous fuel in the same manner during premix operation. It turns out, however, that at different load conditions of the gas turbine plant operating areas are formed in which strong Brennkammerpulsationen, poor burnout and associated high carbon oxides and high levels of unsaturated hydrocarbons occur and in which a poor Querzündverhalten the individual premix burners is observed.

To counteract these problems, is in the DE 101 08 560 A1 proposed the previously applied symmetry in the fuel supply of all Purposefully break up premix burners provided in the multiple burner assembly to effectively reduce the incidence of combustor pulsations. In this case, at least one premix burner is operated such that the at least one premix burner has a different spatial mixing profile within the fuel-air mixture from all other premix burners provided in the multiple burner arrangement. In this case, the at least one premix burner provides a fuel feed for the gaseous fuel, which differs constructively from all other premix burners, along the partial cone shells which radially delimit the conical swirl space. Although this measure contributes to the damping of the usual form in resonant form circularly circulating in an annular combustion chamber pulsations in the upper load range of the gas turbine plant, but are the further influence on the burner behavior with respect to the operation of the gas turbine plant at different load conditions and taking into account other, the combustion processes within the respective premix burner influencing parameters, such as greatly varying moisture content in the combustion air supply with performance increase of the gas turbine, ambient temperature, change in the fuel composition as well as aging phenomena of the entire gas turbine plant limits. Moreover, the above-described proposal does not allow subsequent retrofitability to existing gas turbine plants, so that the known measure can be realized only in new-to-be-acquired gas turbine plants.

A multiple burner arrangement with a multiplicity of individual burners designed as premix burners according to the preamble of claim 1 is known US2003 / 0041588 A1 ,

Presentation of the invention

The invention has the object of providing a multiple burner arrangement with a plurality of trained as Vormischbrennern individual burners, in particular for operating a gas turbine plant according to the preamble of claim 1 such that the operation of a variety of individual premix burners as flexible or variable depending on the particular load condition and the parameter influencing the combustion process, as mentioned above, can be optimized. In particular, it is necessary to create a regulatory option which optimizes the operation of a multiple burner arrangement in terms of pollutant emissions and significantly reduces the pulsations caused by the combustion in the entire load range.

The solution of the problem underlying the invention is specified in claim 1. The subject matter of claim 8 is a method for operating a multiple burner arrangement, as it is suitable for example for the operation of an annular combustion chamber.

The multi-burner arrangement according to the invention is based on the targeted use of stepped premix burner systems which have means for internally staged fuel injection into the swirl chamber for premix operation. For this purpose, each individual premix burner provided in the multiple burner arrangement is supplied with fuel, preferably gaseous fuel, via at least two separate fuel lines, a so-called first and a second fuel line, through which the fuel is fed into the swirl space for further formation of the swirl flow. The respective first fuel line of each premix burner is connected to a first ring line via which the respective first fuel lines of all premix burners within the multiple burner arrangement are supplied with fuel. Furthermore, a second ring line is provided, which is connected to each of the second fuel line of each individual, provided in the multi-burner arrangement Vormischbrenners. It is essential that in a first group of premix burners, the number of which is chosen smaller than half of the total provided in the multiple burner assembly, in at least one of the fuel lines, a fuel supply influencing control unit, such as a throttle valve, is provided. By means of a regulated throttling of the fuel supply with respect to a selected group of premix burners, it is possible, on the one hand, to provide a deliberately asymmetrical temperature profile along an annular premix burner arrangement within the scope of an annular combustion chamber arrangement and thus effectively counteract the burner-induced thermoacoustic oscillations. On the other hand, the controllable fuel throttling allows individual tuning of the burner behavior to basically all parameters influencing the combustion process.

The burner concept according to the invention with controllable fuel throttling, at least for selectively selected premix burners within a multiple burner arrangement, can be realized both with premix burners with burner lances or with external pilot feeds.

When Vorischbrennem with a swirl space at least partially centrally passing burner lance a large part of the preferably gaseous fuel is fed via the burner lance into the swirl chamber during startup or lower load range of the gas turbine. For this purpose, each of the burner lances are connected to the respective first fuel line, which are fed by a respective common ring line with fuel. In the middle and upper load range, however, the multiple burner arrangement is operated such that significantly more than half of the gaseous fuel is supplied via the respective second fuel line to the premix burner via the fuel outlet openings, which extend along the air inlet slots. This is made possible by connecting the fuel supply via the second ring line, from which the respective second fuel lines of the individual premix burners are fed, wherein, as required, the fuel feed via the first loop is throttled. This has the advantage that regardless of the operating point of the gas turbine plant always an ideal air-fuel mixture can be produced in which the individual fuel levels are supplied differently depending on the load range of the gas turbine plant with fuel and in this way an optimum combustion behavior with respect to pollutant emissions and To achieve pulsation behavior, whereby the operating range of the gas turbine can be significantly expanded.

In the same way, with a fuel staging is realized via a burner lance in the middle at least partially projecting burner lance, it is also possible to carry out a fuel staging along the burner air inlet slots. It is also conceivable to realize a fuel staging via an externally guided pilot stage, which is provided at the burner outlet upstream of the combustion chamber.

Regardless of the particular embodiment of the premix burner used as well as the load condition adjustable fuel supply ratio between the ring lines and the first and second fuel lines connected thereto, the inventive burner concept by providing additional control units along the branched off from a ring line fuel lines only for a selected group of provided in the multi-burner arrangement Premixing a targeted disruption of the symmetry in the temperature distribution along the flame forming within the combustion chamber, whereby a decisive influence on the reduction of forming within the combustion chamber thermoacoustic vibrations can be taken. Likewise, the control units provided in the fuel lines, which are preferably designed as throttle valves, allow active regulation or control as a function of parameters influencing the combustion process, such as the varying proportion of moisture in the combustion air supply depending on the load range of the gas turbine arrangement, the ambient temperature, change in temperature Fuel composition as well as aging of gas turbine components.

Brief description of the invention

Fig. 1

Schematisierte Darstellung eines gestuften Vormischbrenners,

Fig. 2 a-c

Darstellung alternativer Brennstoffleitungen zur Brennstoffversorgung eines Vormischbrenners,

Fig. 3a, b

Anordnung zweier Ringleitungen zur Befeuerung einer zweifach gestuften Vormischbrenneranordnung und

Fig. 4

annulares Anordnungsschema für Vormischbrenner zur Befeuerung einer Ringbrennkammer.

The invention will now be described by way of example without limitation of the general inventive idea by means of embodiments with reference to the drawings. Show it:

Fig. 1

Schematized representation of a stepped premix burner,

Fig. 2 ac

Representation of alternative fuel lines for fuel supply of a premix burner,

Fig. 3a, b

Arrangement of two ring lines for firing a two-stage premix burner assembly and

Fig. 4

annular arrangement scheme for Vormischbrenner for firing an annular combustion chamber.

Ways to carry out the invention, industrial usability

Fig. 1 shows a longitudinal section and an oriented against the flow direction S front view of a premix burner 1 with stepped fuel supply. The cone-shaped Vormischbrenner 1 closes with his in Fig. 1 shown highly schematic part cone shells 2 a cone-shaped swirl space 3 a. Due to their mutually overlapping arrangement, the subcone shells 2 each include air inlet slots 4, along which the fuel feed openings 5 are distributed, through which gaseous fuel is fed into the swirl chamber 3 to form a swirl flow.

At the center of the swirling space 3 at least partially projecting a burner lance 6 is provided, which also has fuel outlet openings through which fuel in the swirl chamber 3 can be fed. The fuel feed via the lance stage 6 is preferably carried out when starting the gas turbine plant and in the lower load range. On the other hand, if the gas turbine is located in the middle or upper load range, the fuel feed takes place primarily via the fuel supply openings 5 extending along the partial cone shells.

FIG. 2a schematically shows the fuel supply to a single premix burner in the manner of a FIG. 1 illustrated embodiment. A first fuel line 7 is connected to the lance stage 6, whereas a second fuel line 8 is connected to the fuel inlet openings 5, which extend along the air inlet slots 4 within the Teifkegelschalen 2.

As an alternative to the premix burner variant described above, it is also possible according to a representation in FIG FIG. 2b graduated Premix burner along two axially offset fuel feed areas 9, 10 separately to supply via the fuel lines 7, 8 with fuel.

Another variant of the fuel feed is in Figure 2c illustrated, in which a first fuel stage via an external pilot stage 11, which is provided after the burner outlet and upstream to the combustion chamber BK. The second burner stage corresponds to that in the image representation according to FIG FIG. 2b Along the air inlet slots 4 distributed fuel feed openings 5 along the part cone shells. 2

Out FIG. 3 schematically a piping plan to remove fuel for the individual fuel lines 7, 8, by the premix burner, not shown in the in FIG. 2 supplied with fuel in the manner indicated. In this case, the fuel lines 7 of all premix burners with a first ring line 12 and the fuel lines 8 are connected correspondingly with a second ring line 13. To set a desired fuel supply ratio between the ring lines 12, 13 and thus between the connected to the ring lines 12, 13 fuel lines 7, 8 is at least one control device 14, with a targeted adjustable fuel distribution via the respective ring lines 12, 13 are made can. Further, in a certain number of fuel lines 7, here four, additional control units 15, preferably controllable throttle valves, provided by a targeted throttling of the fuel supply via the example in the first fuel line 7, which is preferably connected to the burner lance, is possible.

In the in FIG. 3 In the illustrated embodiment, four of ten premix burners (not shown) provided in annular array are fueled by respective throttling of the control units 14 via the respective fuel lines 7, whereby the respective premix burners have a combustion temperature different from the combustion temperature of all others in the annular one Arrangement provided unthrottled premix burners. As explained above, this leads to an asymmetry in the temperature distribution along the annular premix burner arrangement, whereby the formation of thermoacoustic oscillations within the combustion chamber can be effectively counteracted. Due to the controllability of the control units 15 designed as throttle valves, it is possible to optimize the combustion process taking into account a wide variety of parameters influencing the combustion process.

In FIG. 4 a schematic representation of a multiple burner arrangement for firing an annular combustion chamber is shown. Equally distributed on an annular surface 18 premix burners are arranged, of which those premix burners are operated unthrottled with a black point, the rest, each marked with a circle throttled, for example, operated with a throttled lance stage. Since, as indicated above, the degree of fuel throttling can be variably adjusted and this ultimately for each individual throttled premix burner, different irregular temperature profiles running along the combustion chamber circumference can be set, which are able to decisively influence the combustion process. By controlled influence on targeted premix burners operable in the multiple burner arrangement, the combustion process can be optimized directly during operation of the gas turbine.

So, suppose that the in FIG. 4 arranged for firing an annular combustion chamber arranged 18 Vormischbrenner with a brennerintemen fuel grading with a lance and a burner stage. While both burner stages are completely open at 12 of the burner, the lance stages are completely closed in the remaining 6 remaining burners. In principle, this burner arrangement permits an operating range which is acceptable in terms of pollutant emissions if 10 to 50% of the fuel supplied to the burners in their entirety is introduced by the lance stage in each case. In this way, it is possible to include the azimuthal burner grouping of the lean burner group To set the burners 1, 4, 7, 10, 13, 16 in a range of 16 - 30% based on the total introduced fuel.

The burner concept according to the invention can be used successfully not only for annular combustion chambers, but also for burner arrangements which provide uniformly distributed or unevenly distributed individual burners, for example for firing a pot combustion chamber. Thus, it is possible by appropriate positioning of throttled premix burner in addition to the already described variant for azimuthal burner grouping also set any radially extending temperature profiles. Variants are also conceivable in which burner arrangements are arranged axially one behind the other, such as, for example, in axially stepped combustion chambers.

LIST OF REFERENCE NUMBERS

1

premix

2

Partial cone shell

3

swirl space

4

Air inlet slot

5

fuel ports

6

Lance, lance level

7.8

fuel line

9, 10

Fuel feed area

11

External pilot stage

12.13

First, second loop

14

control device

15

control unit

Claims (13)

1. Multiple burner arrangement with a plurality of individual burners configured as premix burners (1) which serve to fire a combustion chamber of a thermal engine and each comprise a swirl chamber (3) into which combustion intake air and fuel can be introduced to form a swirl flow, wherein downstream of the premix burner (1) inside the combustion chamber, the swirl flow forms a backflow zone inside which a burner flame forms, wherein the premix burners (1) can be supplied with fuel via at least one first and one second fuel line (7, 8) through which the fuel can be fed into the swirl chamber (3) in order to form the swirl flow, wherein the first fuel line (7) of each premix burner is connected to a first ring line (12), and the second fuel line (8) of each premix burner is connected to a second ring line (13), characterized in that at least for a first group of premix burners, a control unit (15) which influences the supply of fuel is provided in at least one of the fuel lines (7, 8), and that the number of premix burners of the first group is less than half the total number of the plurality of premix burners.
2. Multiple burner arrangement according to claim 1, characterized in that the control unit (15) is a choke valve or an aperture disc.
3. Multiple burner arrangement according to claim 1 or 2, characterized in that the premix burners (1) each have a swirl chamber (3) formed as a partial cone which is delimited radially by at least two mutually partially overlapping part-cone shells (2) which enclose between them a tangential air intake slot (4), and that the fuel feed directed into the swirl chamber (3) takes place via at least two separate fuel feed regions which are separated axially from the part-conical swirl chamber (3) or arranged axially partly overlapping and each connected to a fuel line (7, 8).
4. Multiple burner arrangement according to claim 3, characterized in that a burner lance (6) is provided axially protruding at least partially and centrally into the swirl chamber (3), that a first fuel feed region is provided along the burner lance (6) and a second fuel feed region is provided along the part-cone shells (2), preferably in the region of the air intake slot (4).
5. Multiple burner arrangement according to claim 3, characterized in that a first fuel feed region (9) is provided along the part-cone shells (2), preferably in the region of the air intake slot (4), and a second fuel feed region (10) is provided axially adjacent to the first fuel feed region (9) along the part-cone shells (2).
6. Multiple burner arrangement according to any of claims 1 to 5, characterized in that the plurality of premix burners (1) is arranged in the form of a ring for firing an annular combustion chamber, or in the form of a circular face arrangement for firing a pot-like combustion chamber.
7. Multiple burner arrangement according to any of claims 1 to 6, characterized in that a control device (14) is arranged inside the first and/or the second ring line (12, 13) respectively.
8. Method for operating a multiple burner arrangement with a plurality of individual burners which serve to fire a combustion chamber of a thermal engine and are configured as premix burners (1) which each comprise a swirl chamber (3) into which combustion intake air and fuel are introduced to form a swirl flow, wherein downstream of the premix burner (1) inside the combustion chamber, the swirl flow forms a backflow zone inside which a burner flame forms, wherein the premix burners (1) are divided into at least two groups which are each supplied with different fuel mixtures, wherein the premix burners are supplied with fuel via at least a first and a second fuel line (7, 8) through which the fuel is fed into the swirl chamber (3) to form a swirl flow, wherein the first fuel line (7) of each premix burner is supplied with fuel via a first ring line (12), and the second fuel line (8) of each premix burner is supplied with fuel via a second ring line (13), characterized in that at least for the first group of premix burners, the number of which is less than half of the plurality of individual burners provided in the multiple burner arrangement, the fuel is supplied choked along at least one of the fuel lines.
9. Method according to claim 8, characterized in that the choking of the fuel supply is regulated or controlled.
10. Method according to claim 9, characterized in that the regulation or control of the fuel choking takes place as a function of the load state of the thermal engine, based on the reduction of pulsations forming inside the combustion chamber, a reduction in the pollutant emissions occurring on combustion, and/or as a function of the fuel composition, the ambient temperature and/or the ambient humidity.
11. Method according to any of claims 8 to 10, characterized in that the fuel feed takes place via at least two axially separate fuel feed regions along the swirl chamber (3) of each premix burner.
12. Method according to claim 11, characterized in that a first fuel feed takes place via a burner lance (6) provided centrally inside the swirl chamber (3) and a second fuel feed takes place along part-cone shells (2) radially delimiting the swirl chamber (3).
13. Method according to claim 11, characterized in that a first and second fuel feed take place along part-cone shells (2) radially delimiting the swirl chamber (3).

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