EP2773907A1

EP2773907A1 - Combustion chamber for a gas turbine and burner arrangement

Info

Publication number: EP2773907A1
Application number: EP12780155.3A
Authority: EP
Inventors: Christian Beck; Olga Deiss; Werner Krebs; Bernhard Wegner
Original assignee: Siemens AG
Current assignee: Siemens AG
Priority date: 2011-10-31
Filing date: 2012-10-19
Publication date: 2014-09-10
Also published as: US20140260265A1; CN104024737B; CN104024737A; EP2587158A1; WO2013064383A1

Abstract

The invention relates to a combustion chamber (10, 20) for a gas turbine (1) with at least one combustion zone (23, 24) and at least one burner arrangement (11, 28) for the combustion of a fuel/air mixture in the combustion zone (23, 24), wherein the burner arrangement (11, 28) comprises at least one premixing passage (29) that opens into the combustion zone (23, 24) to provide a fuel/air mixture, and an air supply (32) and at least one fuel supply (33) encompassed in the burner arrangement (11, 28) open into the premixing passage (29). The combustion chamber permits a particularly effective damping of combustion chamber pressure fluctuations. To this end, the air supply (32) is designed in a stepped manner such that the outlet openings (34, 34a, 34b, 34c) of the stepped air supply that open into the premixing passage can be assigned different delay times (τ_1, τ_2, τ₃).

Description

description

The invention relates to a combustion chamber for a gas turbine having at least one combustion zone and at least one burner arrangement for combustion of a fuel / air mixture, wherein the burner arrangement comprises at least one premix passage opening into the combustion zone for providing a fuel / air mixture. Mixture comprises, and merges into the premix ^¬ passage enclosed by the burner assembly air supply and at least one fuel supply.

The invention also relates to a gas turbine with such a combustion chamber and to a burner assembly.

Known gas turbines comprise, in addition to an initially mentioned combustion chamber, a compressor and a turbine. The compressor compresses the gas supplied to the gas turbine, a portion of this air is used to burn fuel in the combustion chamber and a part is used to cool the gas turbine and / or the combustion gases. The provided by the combustion ^¬ process in the combustion chamber hot gases are introduced from the combustion chamber into the turbine, where they relax in this and cool and thereby put under the power of labor turbine blades in rotation. By means of this rotational energy, the gas turbine drives a Arbeitsma ^¬ machine. When working machine beispielswei ^¬ se, it may be a generator.

By said at least one burner assembly ready rack ^¬ te fuel / air mixture is pre-mixed in a Vormischpassage the minimum quantity to be then ignited after introduction into the combustion zone. The premixing of the fuel with the air reduces the pollutant emissions produced during the combustion, in contrast to the previously customary direct injection of the fuel into the combustion zone. A disadvantage of the premix of the fuel However, this arrangement is much more susceptible to the formation of combustion chamber pressure fluctuations. If there is pressure fluctuations in the combustion zone, also arise fluctuations in concentration in the fuel / air mixture in the Vormischpassage which result in the combustion to heat control ^¬ reduction fluctuations. These thermoacoustic instabilities in turn increase the combustion chamber pressure fluctuations, wherein there are preferred frequencies in the arrangement for these aufschaukelnden combustion chamber pressure fluctuations. The concentration fluctuations in the fuel / air mixture, ie temporal variations in the air-fuel mixture ratio ^¬ can also be referred to with Luftzahlschwankungen. The air number fluctuations result from different acoustic resistances of the air supply and fuel supply. For damping the combustion chamber pressure fluctuations, known gas turbines comprise resonators arranged in the housing. Since the resonators are directly adjacent to the combustion zone and also interrupt a heat shield arrangement in the housing and therefore have to be cooled, such a design of the combustion chamber is expensive. An alternative embodiment of a known combustion chamber provides for suppression of such combustion chamber ^pressure fluctuations that the fuel nozzles opening into the premix passage are distributed along the premix passage in the axial direction, so that mixing zones with different delay times are formed in the premix passage. This staged design of the fuel supply makes it possible to mitigate the variations in concentration in the fuel injected by the fuel supply caused by the combustion chamber pressure fluctuation. The fuel nozzles may also be referred to as exhaust ports of the fuel supply.

The object of the invention is to provide a combustion chamber of the type mentioned and a gas turbine with such a combustion chamber and a burner arrangement comprising such a combustion chamber, which allows a particularly effective Dämp ^¬ tion of combustion chamber pressure fluctuations. The object is achieved according to the invention in a combustion chamber of the type mentioned above in that the air supply is stepped, so that different delay times can be assigned in the Vormischpassage mün ^¬ denden outlet openings of the stepped air supply.

By the known BrennstoffZuführung with along the Vormischpassage distributed in the axial direction arranged fuel nozzles can indeed be caused by combustion chamber pressure fluctuations fluctuations in the ^amount of fuel from ^¬ same, which is mixed with the air flow along the Vormischpassage. This known gradation can not jet so einzu- on ^¬ due to the different acoustic resistances of the air and fuel the fuel into the air stream that a constant ratio of fuel and air and a constant amount of fuel per time from the pre ^¬ mixing passage off and enters the combustion zone. Therefore he ^¬ inventively to suppress combustion chamber pressure fluctuations and also proposed by Wärmefreisetzungsfluktu ^¬ ation, the train stepped confluent air supply into the Vormischpassage and thus mitigate the caused by combustion chamber pressure fluctuations Density fluctuations in the Vormischpassage passing airflow. Due to the high compressibility of the air compared to, for example, liquid fuel and the lower pressure in the air supply line compared to the pressure in the fuel supply line, this is particularly effective for suppressing combustion chamber pressure fluctuations.

According to the invention, the stepped air supply comprises opening into the Vormischpassage outlet openings, which difference ^¬ Liche delay times are assigned. The stepped air supply may further comprise further outlet openings, which redundant delay times can be assigned. The delay time can also be referred to as convective time delay. It is determined from the time it takes for a fluid element entering the premix ^passage to escape combustion. ne to arrive. The outlet openings can also be referred to with outlet openings.

For example, the burner assembly may include a pilot burner having a premix passage with a pilot burner lance centrally disposed therein, the pilot burner lance connected to a fuel supply and including fuel nozzles. In the premix passage of the pilot burner opens an air supply. Around the pilot burner, a plurality of main mixers included in the burner assembly can be arranged. Each of the main mixers may comprise a premix passage, which is enclosed by a cylindrical housing, into which an air feed opens and in which a lance with fuel nozzles connected to a fuel feed is arranged axially. The lance can be supported on the housing, for example via swirl ^blades . According to the invention, at least one of the premix passages in the exemplified burner arrangement comprises a stepped air supply. For example, each of the air supply of the

Shaped main mixer be formed by the spin show ^¬ feln form in the Vormischpassage opening air outlet openings, which different delay times can be assigned. These can preferably be chosen such that cancel or weaken each other at least in the frequency range of a preferred combustion chamber pressure fluctuation caused by this density fluctuations in the supplied air by means of the different delay times of the air outlet openings. An advantageous development of the invention may provide that an additional opening into the Vormischpassage and pressurized with gaseous fuel fuel supply is also formed ge ^¬ ranks to the step-formed air supply.

Since the gaseous fuel also has a high compressibility compared to air, can be through the additional grading of gaseous fuel can be more effectively damped act on fuel supply caused by fluctuations in the combustion chamber pressure fluctuations in concentration and density of the flowing from the Vormischpassage in the combustion zone fuel / air mixture. If the premix passage comprises more than one fuel feedstock that can be supplied with gaseous fuel, one or more of these fuel feeds which can be acted upon by gaseous fuel can be designed in a stepped manner.

Advantageously, it can further be provided that delay times can be assigned to the outlet openings of the stepped feed, wherein for a minimum delay time x _mn and a maximum delay time ^~ u _max with respect to a combustion chamber pressure fluctuation of the frequency f to be suppressed: ^~ u _max -T _m i _n > 1 / f.

By the condition it is ensured that are to be suppressed combustion chamber pressure fluctuation effectively attenuated by this induced density variations in the supplied by the stepped feed fluid at least in the frequency ^¬ frequency range. The staged feeder is the staged air supply. If further feeds leading into the premix passage are formed in a stepped manner, the condition can also apply to these feeds. The specified in the condition of minimum and maximum Ver ^¬ zugszeit refers to the shortest and the longest of the delay times that are associated with the outlet of a feeder.

It can also be considered advantageous that the outlet openings of the stepped feed opening into the premix passage are arranged such that density fluctuations caused by at least one preferred combustion chamber pressure fluctuation of the frequency f in the fluid supplied through the outlet openings in the premix passage due to the outlet openings different types of superimpose train times so that they essentially cancel each other out.

According to an advantageous development of the invention it can be provided that the burner arrangement is arranged in the region of a second axial stage with at least one premix passage opening into the combustion zone, the combustion zone following downstream of a first combustion zone with a first burner arrangement.

By means of a second axial stage, the heat release over the entire available combustion chamber can be further distributed, so that the tendency of the combustion system to thermoacoustic instabilities is further reduced. In addition, a staged air supply to at least one

Vormischpassage the burner assembly of the second axial stage in terms of apparatus particularly easy to implement.

A preferred embodiment of the invention may provide that the burner arrangement comprises a fuel distributor ring arranged outside around a combustion chamber housing and a multiplicity of premix passage, wherein the premix passages open into the combustion zone with their one end into the combustion chamber and with at least one of the fuel distributor ring branching fuel supply correspond, at least along one of the premixing say outlet openings of a stepped air supply are distributed. This stepped air supply to at least one Vormischpas ^¬ say the burner arrangement of the second axial step is particularly simple in equipment to realize. The premixing passages may, for example, have a tubular design, wherein the situation of the air outlet openings along the premixing passages or the corresponding delay times relative thereto may be adaptable to the frequency of the combustion chamber pressure fluctuations to be suppressed. For example, the tubular Pre-mixing passage made of an elastic material whose length - and thus also the corresponding to the outlet openings delay times - is adaptable to a frequency to be suppressed.

Another object of the invention is to provide a gas turbine with at least one combustion chamber mentioned above, which allows a particularly effective damping of combustion ^¬ chamber pressure fluctuations.

For this purpose, the gas turbine on at least one combustion chamber, which is designed according to one of claims 1 to 4.

Another object of the invention is to provide a encompassed by the initially mentioned combustion chamber burner assembly, which allows a particularly effective damping of internal ^¬ chamber pressure fluctuations.

For this purpose, the burner assembly is part of the combustion chamber according to one of claims 1 to 4.

Further expedient configurations and advantages of the ^invention are the subject of the description of Ausführungsbeispie ^¬ len of the invention with reference to the figure of the drawing, wherein like reference symbols refer to identically acting components ver ^¬.

FIG. 1 shows a schematic sectional view of a gas turbine according to the prior art,

2 shows a detail of a combustion chamber with second axial stage according to an embodiment of the invention in a schematic sectional view, and 3 shows a detailed view of that shown in FIG

Embodiment in the region of the stepped air ^¬ supply in a schematic sectional view. 1 shows a schematic sectional view of a gas turbine 1 ^¬ according to the prior art. The gas turbine 1 has inside a rotatably mounted about a rotation axis 2 rotor 3 with a shaft 4, which is also referred to as a turbine runner. Along the rotor 3 successively follow an intake housing 6, a compressor 8, a combustion system 9 with a number of combustion chambers 10, each comprising a burner assembly 11 and a combustion chamber housing 12, a turbine 14 and an exhaust housing 15. The combustion system 9 communicates with an beispielswei ^¬ se annular hot gas duct. There form a plurality of successive turbine stages, the turbine 14. Each Turbi ^¬ nenstufe is formed of blade rings. Viewed in the flow direction of a working medium follows in the hot runner formed by a number 17 vanes row formed from blades 18 row. The guide vanes 17 are secured to an inner housing of a stator 19 while the rotor blades 18 ^¬ a number, for example, by means of a Turbi ^¬ nenscheibe on the rotor 3 are attached. Coupled to the rotor 3 is, for example, a generator (not shown).

During operation of the gas turbine, air is sucked in and compressed by the compressor 8 through the intake housing 6. The compressed air provided at the turbine-side end of the compressor 8 is led to the combustion system 9 where it is mixed with a fuel in the area of the burner assembly 11. The mixture is then burned by means of the burner ^arrangement 11 to form a working gas stream in the combustion system 9. From there, the working gas stream flows along the hot gas channel past the guide vanes 17 and the rotor blades 18. At the rotor blades 18, the working gas stream relaxes in a pulse-transmitting manner, so that the running Blades 18 drive the rotor 3 and this coupled to him generator (not shown).

2 shows a section of a combustion chamber 20 of a gas turbine according to an embodiment of the invention. The combustion chamber 20 has a combustion chamber housing 21, which is rotationally symmetrical about an axis 22. In the combustion chamber housing 21 is a first combustion ^¬ zone 23 and a second combustion zone 24, wherein the second combustion zone 24 downstream - with respect to a flow direction Hauptströ ^¬ 26 - following the first combustion zone 23rd The combustion chamber 20 comprises a first burner array (not shown) and a second burner assembly 28 to the Burn ^¬ voltage of a fuel / air mixture into the secondary combustion zone 24. The second burner assembly 28 includes an opening into the second combustion zone 24 Vormischpassage 29 to provide a fuel / air mixture, wherein in the Vormischpassage 29 includes an included from the second burner assembly 28 air supply 32 and a fuel supply 33, wherein the air supply 32 is stepped, so that the opening into the Vormischpassage 29 outlet ^¬ openings 34 of the stepped air supply 32 different delay times can be assigned. The second burner arrangement 28 is thus arranged in the region of a second axial step. Comprises the second burner assembly 28 includes an externally around the combustion chamber housing 21 around at ^¬ subordinate fuel manifold ring 36 and a plurality of Vormischpassagen 29, wherein the Vormischpassagen 29 into open at one end 37 to the combustor casing 21 in the second combustion zone 24 and respectively with one of the Fuel distributor ring 36 branching fuel supply 33 correspond, wherein along at least one of the Vormischpassagen 29 outlet openings 34 of a stepped air supply 32 are arranged distributed.

According to an advantageous embodiment of the illustrated embodiment of the invention, each of the premixing say 29 of the second burner assembly 28 have a stepped air supply 32.

The fuel injected into the premix passage 29 through the fuel feeder 33 mixes with the air entering the premix passage 29 through the discharge ports 34, so that a fuel / air mixture flows in the flow direction 39 along the premix passage. An air volume exiting from an outlet opening 34 will mix with the fuel and, depending on the position of the outlet opening 34, will require a period of time to enter the

To reach combustion zone 24. This period of time is referred to as the delay time and is determined by the time it takes for a fluid element entering the premix passage to reach the combustion zone. The outlet openings 34 arranged along the premix passage 29 correspond with different delay times due to their different arrangement in the premix passage 29. Each of the outlet openings 34 in the premix passage 29 can thus be assigned different delay times.

3 shows a detailed view of Darge in Figure 2 ^¬ presented combustion chamber according to an embodiment under the second burner assembly of a second axial step. Shown is a section of the

Combustor housing 21, which is a first combustion zone

23 (partially shown) and a to these downstream ^¬ Windwärts subsequent second combustion zone 24 (partially shown) surrounds wherein a comprised Vormischpassage arrangement of the second burner 29 for providing egg ^¬ nes fuel / air mixture in the second combustion zone

24 opens. In the tube-shaped Vormischpas ^¬ say 29 opens a fuel supply 33 for injecting fuel 35 into the Vormischpassage 29 and a Luftzufüh- tion 32 which is stepped. The step-out ^¬ formed air supply 32 includes in the Vormischpassage 29 opening into outlet openings 34a, 34b, 34c for supplying air 40, wherein the outlet openings 34a, 34b, 34c sub- different delay times x _lr x ₂ , 1 3, are assignable. In ^¬ play, a leaking from the outlet port 34a air volume is to mix with the injected by the fuel supply 33 to flowing fuel 35 and this need, starting from the position of the outlet opening 34a a period ii in order to reach the two BWA combustion zone 24th For damping or suppressing a combustion chamber pressure fluctuation of the frequency f, the position of the outlet openings 34a, 34b and 34c can advantageously be selected such that ii-X3> 1 / f. The density fluctuations of the air caused by the combustion chamber ^pressure fluctuation of the frequency f in the outlet openings can be superimposed upon ignition of the fuel / air mixture in the second combustion zone 24 due to the different delay times x _lr x ₂ , 1 3 such that these density fluctuations essentially cancel each other out. For this purpose, the arrangement of the outlet openings 34a, 34b, 34c along the premix passage 29 can be selected accordingly. The combustion chamber pressure fluctuation of the frequency f may be a combustion chamber pressure fluctuation which can preferably be excited on account of the design of the combustion chamber. This can also be referred to with preferential combustion chamber pressure fluctuation. A further development of the illustrated embodiment can also Vorse ^¬ hen, is excluded that the fuel supply 33 is also stepped (not shown here).

Claims

claims

1. combustion chamber (10,20) for a gas turbine (1) with

- At least one combustion zone (23,24) and

at least one burner arrangement (11, 28) for combustion of a fuel / air mixture in the combustion zone (23, 24),

wherein the burner arrangement (11, 28) comprises at least one premix passage (29) discharging into the combustion zone (23, 24) for providing a fuel / air mixture, and one in the premix passage (29) from the burner arrangement (11, 28) comprising air supply (32) and at least one fuel feed (33) opens,

characterized in that the air supply (32) is stepped, so that in the premix passage (29) opening outlet openings (34, 34a, 34b, 34c) of the stepped air supply different delay times (τι, T2, 13) can be assigned, wherein for a mini ^The _{delay time} τ _πι ± _η and a maximum _{delay time} ^~ u _max in relation to a suppressing combustion chamber pressure fluctuation of the frequency f are: T _max -T _min > 1 / f and the outlet openings (29) opening into the premixing ^gas (29) 34, 34a, 34b, 34c) of the stepped air supply (32) are arranged such that density fluctuations caused by at least one preferred combustion chamber pressure fluctuation of frequency f in the fluid supplied through the outlet openings (34a, 34b, 34c) in the premix passage (29 ) on the basis of the outlet openings (34, 34a, 34b, 34c) associated different delay times (τι, τ ₂ , τ ₃ ) superimpose such that they are essentially against each other pick it up.

2. combustion chamber (10,20) according to claim 1,

characterized in that in addition to the staged formed air supply (32) in the Vormischpassage (29) opening and can be acted upon with gasför ^¬ migem fuel supply is also stepped.

3. combustion chamber (10, 20) according to one of the preceding claims,

characterized in that the burner assembly (28) is arranged in the region of a second axial step with at least one in the Burn ^¬ drying zone (24) opening out Vormischpassage (29), wherein the combustion zone (24) downstream to a first combustion zone (23) first with a Burner assembly (11) follows.

4. combustion chamber (10, 20) according to claim 3,

The burner assembly (28) includes a fuel distributor ring disposed around a combustion chamber housing (12, 21) around the outside of the combustion chamber housing (12, 21)

(36) and a plurality of Vormischpassage (29), wherein the Vormischpassagen (29) open with its one end in the combustion chamber housing (12, 21) into the combustion zone (24) and with at least one of the Brennstoffverteiler- ring (36 ) branching fuel supply (33), at least along one of the Vormischpassagen (29) outlet openings (34, 34a, 34b, 34c) of a stepped air supply (32) are arranged distributed.

5. Gas turbine (1) with at least one combustion chamber (10, 20), d a d e c e c e n e c e n e s, at least one combustion chamber (20) according to one of claims 1 to 4 is formed.

6. burner arrangement (28) for a gas turbine (1),

It is a part of the combustion chamber (20) according to one of the claims

1 to 4 is.