GAS TURBINE BURNER HUB WITH PILOT BURNER

Abstract

A burner arrangement for a combustion chamber for combustion of fluid fuels has a main burner and pilot burner arranged centrally within the main burner for the ignition and/or stabilization of the combustion of the main burner. The main burner has central fuel feed arrangement arranged around the pilot burner, an annular air duct surrounding the central fuel feed arrangement for the supply of combustion air, first fuel nozzles for injection of substantially gaseous fuel into the annular air duct. The first fuel nozzles are fed from a first fuel distributor in the central fuel feed arrangement, and second fuel nozzles for the injection of a substantially liquid fuel into the annular air duct are fed from a second fuel distributor in the central fuel feed arrangement. Ducts are provided which branch off from at least one of the fuel distributors and issue into the pilot burner.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application is the US National Stage of International Application No. PCT/EP2014/072741 filed Oct. 23, 2014, and claims the benefit thereof. The International Application claims the benefit of German Application No. DE 102013222152.5 filed Oct. 31, 2013. All of the applications are incorporated by reference herein in their entirety.

FIELD OF INVENTION

The invention relates to a burner arrangement, in particular a burner arrangement with a main burner and a pilot burner, and to the mixing of fuel with air.

BACKGROUND OF INVENTION

When operating a gas turbine plant, the mixing of fuel with air is of crucial significance, if optimum and consequently low-pollutant combustion is to be achieved. For this purpose, fuel is injected in a maximally precisely metered manner and fed to the combustion air. To achieve good mixing of the fluids, both the combustion air and the fuel are set in swirling motion by structural measures. This is typically mainly achieved by curved vanes and fuel nozzles.

The increasingly stringent stipulations relating to pollutant reduction require constant improvement of combustion. Pollutants such as nitrogen oxides (NO_x) are mainly influenced by the mixing ratio of fuel to air and the efficiency of combustion. Complete combustion of the fuel is desirable if pollutants are to be reduced.

Possible fuels are gaseous fuels, such as natural gas or synthesis gas, and also liquid fuels. It is precisely in the case of the liquid fuel oil that nozzle geometry in combination with vane swirl has hitherto primarily influenced mixing of said fuel with air. No further active influencing of for example the depth of penetration of the fuel into the air stream or the swirling of the fuel and thus optimized mixing does not conventionally take place.

In the case of gas premixing injection, the gas is injected for example via bores in a swirl vane and premixed and swirled with the compressed air.

With both fuels, gas and oil, a pilot burner is typically used to stabilize the premixing flame. In the case of oil, this is an oil diffusion burner, while in the case of gas it is a pilot gas burner.

SUMMARY OF INVENTION

An object of the invention is to further develop the above-stated device such that, when the device is in operation, maximally complete combustion is achieved.

According to aspects of the invention, this object is achieved by the burner arrangement according to the independent claim. Advantageous further developments of the invention are defined in the dependent claims. In a burner arrangement for a combustion chamber, in particular a gas turbine combustion chamber, for burning fluid fuels, with a main burner and a pilot burner arranged centrally therein, which pilot burner serves to ignite and/or to stabilize main burner combustion, the main burner comprising a central fuel feed arrangement arranged around the pilot burner, an annular air duct surrounding the central fuel feed arrangement for supplying combustion air, first fuel nozzles for injecting a substantially gaseous fuel into the annular air duct, wherein the first fuel nozzles are supplied by a first fuel manifold in the central fuel feed arrangement, and second fuel nozzles for injecting a substantially liquid fuel into the annular air duct, wherein the second fuel nozzles are supplied by a second fuel manifold in the central fuel feed arrangement, ducts are provided which branch off from at least one of the fuel manifolds and lead into the pilot burner and the pilot burner has a gas feed duct independent of the ducts, thereby ensuring that the pilot flame is enhanced as a result of removal from the premixing passage of the diagonal swirler in the main burner and addition to the pilot burner, whereby combustion is improved and the emissions therefrom are reduced.

In this case, it is convenient if the pilot burner comprises a pilot annular air duct for supplying combustion air and the ducts lead into this pilot annular air duct.

To be able to supply the fuel as uniformly as possible to the pilot annular air duct, it is advantageous for the ducts leading into the pilot annular air duct to be uniformly distributed around the circumference thereof.

In this respect it is convenient, because it is simple and inexpensive to implement, for the ducts to take the form of bores.

In one advantageous embodiment, the ducts branch off from the second fuel manifold and comprise nozzles at their ends leading into the pilot burner. The second fuel manifold for injecting a substantially liquid fuel, i.e. oil, is mechanically particularly stressed, such that it is particularly advantageous here for the nozzles to be cavitation-free and screw-fastenable should replacement be required.

With regard to the best possible intermixing of fuel and air, it is advantageous for the annular air duct to comprise swirl vanes and for the first fuel nozzles to be arranged in these swirl vanes.

The admixture of fuel from the central fuel feed arrangement does not however replace the independent supply of gas or oil in the pilot burner, but rather in combination therewith ensures additional fuel enrichment, for which reason in advantageous embodiments the pilot burner also comprises an oil feed duct independent of the ducts, in addition to a gas feed duct independent of the ducts.

The additional mass flows according to the invention from the gas or oil manifolds are mixed with the compressed air in the pilot gas line and then combined with the fuel in the pilot burner. This makes possible additional fuel enrichment and mixing, which may lead to an improvement in the fuel/air mixture and thus to a reduction in pollutants.

The invention may also be implemented in an existing design by the simple introduction of bores and/or nozzles.

BRIEF DESCRIPTION OF THE DRAWINGS

The FIGURE shows schematically, and not to scale, a burner arrangement according to the invention.

DETAILED DESCRIPTION OF INVENTION

The invention is described in greater detail below with reference to a drawing. The FIGURE shows schematically, and not to scale, a burner arrangement 1 according to the invention, which may optionally be used in conjunction with a plurality of similar burner arrangements for example in the combustion chamber of a gas turbine plant. The burner arrangement 1 has a main axis 19 and comprises a pilot burner 3 and a main burner 2 concentrically surrounding the pilot burner 3. Both pilot burner 3 and main burner 2 may optionally be operated with gaseous and/or liquid fuels, such as for example natural gas or heating oil. The pilot burner 3 then comprises as fuel ducts an inner oil feed duct 18 and an inner, annular gas feed duct 17 concentrically surrounding said duct 18. This is in turn surrounded concentrically by a pilot annular air duct 13 for supplying combustion air 14.

In or on this pilot annular air duct 13 it is additionally possible to arrange a suitable ignition system (not shown in the FIGURE).

In the pilot annular air duct 13 there are additionally arranged swirl vanes 20, which comprise fuel nozzles 21 for supplying a fuel to a stream 14 of oxygen-containing gas, typically air.

The main burner 2 surrounding the pilot burner 3 comprises, relative to the main axis 19, a radially outer annular air duct 5 for the combustion air 6, through which extend a plurality of swirl vanes 16 of a swirl vane assembly. These swirl vanes 16 have as inlet for fuel first fuel nozzles 7, through which fuel gas may be injected into the air 6 flowing in through the annular air duct 5. The first fuel nozzles 7 are supplied via a first fuel manifold 8 in a central fuel feed arrangement 4. A second fuel manifold 10 in the central fuel feed arrangement 4 supplies second fuel nozzles 9 typically with oil.

The task of the pilot burner 3 is to maintain stable combustion operation in the burner arrangement 1, since this is mostly operated with a lean mixture with a tendency towards instability.

In the example in the FIGURE, the invention provides not only ducts 11 which branch off from the first fuel manifold 8 for the gas supply and lead into the pilot burner 3 but also ducts 12 which branch off from a second fuel manifold 10 for oil. The ducts 12 have nozzles 15 at their ends leading into the pilot burner 3.

The ducts 11, 12 are distributed uniformly over the circumference of the pilot annular air duct 13 and may take the form of simple bores.

Claims

1. A burner arrangement for a combustion chamber for burning fluid fuels, comprising:

a main burner and a pilot burner arranged centrally therein, which pilot burner serves to ignite and/or to stabilize main burner combustion,

the main burner comprising a central fuel feed arrangement arranged around the pilot burner, an annular air duct surrounding the central fuel feed arrangement for supplying combustion air, first fuel nozzles for injecting a substantially gaseous fuel into the annular air duct, wherein the first fuel nozzles are supplied by a first fuel manifold in the central fuel feed arrangement, and second fuel nozzles for injecting a substantially liquid fuel into the annular air duct, wherein the second fuel nozzles are supplied by a second fuel manifold in the central fuel feed arrangement,

wherein ducts are provided which branch off from at least one of fuel manifolds and lead into the pilot burner and the pilot burner has a gas feed duct independent of the ducts.

2. The burner arrangement as claimed in claim 1,

wherein the pilot burner comprises a pilot annular air duct which supplies combustion air and the ducts lead into this pilot annular air duct.

3. The burner arrangement as claimed in claim 2,

wherein the ducts leading into the pilot annular air duct are uniformly distributed around the circumference thereof.

4. The burner arrangement as claimed in claim 1,

wherein the ducts take the form of bores.

5. The burner arrangement as claimed in claim 1,

wherein the ducts branch off from the second fuel manifold and have nozzles at their ends leading into the pilot burner.

6. The burner arrangement as claimed in claim 5,

wherein the nozzles are cavitation-free and screw-fastenable.

7. The burner arrangement as claimed in claim 1,

wherein the annular air duct comprises swirl vanes and the first fuel nozzles are arranged in these swirl vanes.

8. The burner arrangement as claimed in claim 1,

wherein the pilot burner comprises an oil feed duct independent of the ducts.

9. The burner arrangement as claimed in claim 1,

wherein the combustion chamber comprises a gas turbine combustion chamber,