EP1235033A2 - Annular combustor and method of operating the same - Google Patents

Abstract

The method for operating an annular combustion chamber (13) with a series of premixing burners (1, 2) comprises operating at least one burner (2) so that it produces an air/fuel mixture with a different spatial profile (12) to all the others. E- An Independent claim is included for an annular combustion chamber for use in the method.

Description

Technical field

The invention relates to a method for operating an annular combustion chamber as well as an annular combustion chamber with a large number of circularly arranged premix burners, in which a fuel-air mixture is generated before it is used Ignition brought and as a hot gas stream to drive at least one turbine stage a gas turbine plant is used.

State of the art

When burning liquid or gaseous fuel in a combustion chamber The so-called premix combustion has established itself in a gas turbine. in this connection the fuel and the combustion air are premixed as evenly as possible and then passed into the combustion chamber. For ecological reasons to be fair, you pay attention to a low flame temperature by means of a large excess air. In this way, the nitrogen oxide formation can be kept low become.

In this context, so-called ring combustion chambers have prevailed, which a multitude of individual premixing burners in a circular arrangement around the provides rotating components of a gas turbine and their hot gases over one annular flow channel immediately downstream of the turbine stage be fed.

A related ring burner with premix burners for a gas turbine is known for example from EP-B1-597 138. The one at the head of the ring combustion chamber Premix burners provided are, for example, from EP-A1-387 532 known. Such premix burners are so-called double-cone burners. This type of premix burner essentially consists of two hollow, conical partial bodies, which are nested in the direction of flow are. The respective central axes of the two partial bodies are against each other added. The adjacent walls of the two partial bodies form in their longitudinal extent tangential slots for the combustion air, which in this way in the Burner inside. A fuel nozzle for liquid fuel is arranged there. The fuel is injected into the hollow cone at an acute angle. The emerging conical liquid fuel profile is from the tangentially flowing Combustion air enclosed. In the axial direction, the concentration of the Fuel continuously degraded as a result of mixing with the combustion air.

The premix burner can also be operated with gaseous fuel. For this purpose, in the area of the tangential slots in the walls of the two partial bodies longitudinally distributed gas inflow openings, the so-called premix holes, intended. In gas operation, the mixture formation begins with the combustion air thus already in the zone of the entry slots. It is understood that on mixed operation with both types of fuel is possible in this way. At the burner outlet the fuel concentration is as homogeneous as possible above the applied circular cross-section. It arises at the burner outlet a defined dome-shaped backflow zone, at the top of which the ignition takes place.

Now is from various publications, such as Combust. Sci. and tech. 1992, vol. 87, pages 329 to 362 that, in the case of a perfectly premixed flame, the size of the backflow zone, which is synonymous with the so-called flame stabilization area, has no influence on the nitrogen oxide emissions.

On the other hand, however, the carbon dioxide emissions as well as the emissions regarding unsaturated hydrocarbons (UHC) and especially the extinguishing limits the respective premix burner is strongly influenced by the size of the backflow zone. This means that the larger the backflow zone, the more the carbon dioxide emissions fall, the emissions with respect to unsaturated ones Hydrocarbons as well as the extinction limit. This also means that with a larger backflow zone covered a larger load range of the premix burner can be extinguished without extinguishing the flame. In addition to the size of the Backflow zone, which, as explained above, has a decisive influence on the mode of operation the individual premix burner also plays the fuel distribution, i.e. the mixture profile of the fuel / air mixture in the area of flame stabilization a major role. In a manner known per se, the mixture profile between fuel and air inside the premix burner through the premix perforation pattern determined, i.e. the spatial arrangement of the typically along the air inlet slots distributed openings through which premix fuel, preferably Premix gas is injected into the interior of the premix burner.

Normally, all ring combustion chambers are used to operate a gas turbine Premix burner equipped with identical premix perforation patterns. It shows however, that is due to the different load conditions of the gas turbine system Operating areas of the gas turbine arise which are caused by strong combustion chamber pulsations, bad burnout with regard to carbon oxide values and values of unsaturated Hydrocarbons and poor cross-ignition behavior of the individual premix burners Marked are. This needs to be significantly improved.

Presentation of the invention

The invention has for its object a method for operating an annular combustion chamber and a related annular combustion chamber with a plurality of circularly arranged premix burners, in each of which a fuel-air mixture is generated before it is ignited and as a hot gas stream for driving at least one turbine stage of a gas turbine system is used to develop in such a way that the disadvantages mentioned above are to be avoided. In particular, measures are to be taken which decisively counteract the combustion chamber pulsations that occur. Furthermore, for environmental reasons and the increasingly stringent requirements regarding emission values, the burnout should be completed and the CO, UHC, NO _X emissions that occur should be reduced.

According to the invention is a method for operating a combustion chamber with a plurality circularly arranged premix burner according to the preamble of the claim 1 designed such that at least one premix burner is operated in such a way that the at least one premix burner is one of all other premix burners deviating spatial mixture profile within the fuel-air mixture having.

According to the invention, the object is also achieved by an annular combustion chamber the preamble of claim 5, solved in that at least one premix burner one of all other premix burners at least one area in the Has premix gas perforation in which neighboring premix gas holes have a different one Have a distance from each other than in the rest of the premix gas perforation.

The idea on which the invention is based is based on the targeted refraction of the symmetry from the circular arrangement of a large number of identically trained Premix burners around the rotating components of a gas turbine system is structurally predetermined. Since the premix burner is usually identical in construction are arranged in a ring around the rotating components of the gas turbine system, which, due to their identical training, each have identical mixing profiles within of the individual fuel-air mixtures - this is the result of identical ones Premix perforation patterns - form in certain load ranges of the Annular combustion chamber circularly circulating, pulsating waves that need to be targeted suppress.

On the other hand, if you force the well-known symmetrical structure, a targeted one Asymmetry due to which by the constructive identity of all premix burners generated symmetry is broken, so there can be no circular orbiting Pulsation vibrations, which can ultimately be attributed to resonant causes, to adjust.

1. stabilere Flammenposition

2. tiefere Emissionen hinsichtlich CO, UHC, NO_X

3. vollständiger Ausbrand

4. größerer Betriebsbereich ohne Flammenlöschung

5. verbessertes Querzündverhalten zwischen zwei benachbarten Vormischbrennern, sowie

6. geringere Pulsationen.

Such asymmetry is enforced according to the invention in that at least one, preferably three or more premix burners have different premix perforations, the premix perforation patterns of which differ from all other premix burners. Through the targeted use of premix perforation patterns that differ from the usually equally distributed premix perforation patterns, different mixture profiles are generated, which in turn lead to different burnout results. Ultimately, this leads to a decisive damping or control of pulsations which usually circulate in the ring combustion chamber and which form in a resonant form. In particular, the measure according to the invention leads to the following advantages:

1. more stable flame position

2. Lower emissions in terms of CO, UHC, NO _X

3. complete burnout

4. Larger operating area without flame extinguishing

5. Improved cross-ignition behavior between two adjacent premix burners, as well

6. lower pulsations.

Brief description of the figures

Fig.1

einen Längsschnitt durch zwei benachbarte zirkular innerhalb einer Ringbrennkammer angeordnete Vormischbrenner gemäss dem Schnitt I-I in der Figur 2 zeigt und

Fig.2

eine Ansicht gemäss der Linie II-II in der Figur 1 darstellt.

The invention is described below by way of example without limitation of the general inventive concept using an exemplary embodiment with reference to the drawing, wherein

Fig.1

2 shows a longitudinal section through two adjacent premix burners arranged circularly within an annular combustion chamber, according to section II in FIG

Fig.2

is a view along the line II-II in Figure 1.

Only the elements essential to the invention are shown. Same elements are identified in the same way in different figures.

WAYS OF CARRYING OUT THE INVENTION, INDUSTRIAL APPLICABILITY

In Fig. 1 is a longitudinal section along the line I-I in Figure 2 through two adjacent Premix burners 1, 2 are shown, which are arranged side by side on an annular circumferential Front plate 3 of an annular combustion chamber 13 are arranged. A schematic View according to line II-II in FIG. 1 on the ring combustion chamber 13 is in of Figure 2 visible. The conical premix burners 1, 2 have an outlet opening 4, 5, which open downstream into the combustion chamber 6. The premix burner 1, 2 have a premix fuel perforation along their air inlet slots 7, 8 9, which consists of individual openings through which preferably gaseous fuel 10 into the interior of the conical premix burner 1, 2 flows.

The spatial distribution of the premix gas perforation 9 of the premix burner 1 is shown in conventionally distributed homogeneously, i.e. the premix gas holes are equidistant spaced from each other. With such a premix perforation pattern usually becomes a spatially uniformly distributed, homogeneous mixture profile 11 achieved over the entire cross section of the outlet opening 4.

In contrast, the premix burner 2 has two areas along the premix perforation pattern in which the individual premix gas holes 9 different distances to each other. With the in the exemplary embodiment according to FIG. 1 shown premix perforation pattern of the premix burner 2, in which the downstream arranged premix holes have a greater mutual distance than upstream, a mixture profile 12 is obtained which is designed in the manner of a Gaussian distribution is. By providing such a premix burner 2 in the circular Overall arrangement of all premix burners within the annular combustion chamber 13 can a targeted asymmetry in combustion behavior along the circular Hot gases are introduced, which, as stated above, is effective the formation of combustion chamber pulsations can be counteracted.

As indicated in FIG. 2, in order to effectively avoid the aforementioned Pulsations within the combustion chamber of at least three premix burners 2 formed in the above manner and circularly evenly distributed around the annular combustion chamber 13 may be arranged.

It is also conceivable to add the premix perforation pattern to the premix burner 2 invert, i.e. the mutual distances upstream within the premix burner larger than the premix openings downstream of the premix burner 2, whereby a correspondingly inverted mixture profile with respect to that in FIG Reference to the premix burner 2 shown mixing profile can be generated can.

Of course, it is also possible to use more of the homogeneous premix perforation arrangement to implement different premix perforation patterns.

LIST OF REFERENCE NUMBERS

1, 2

premix

3

Front plate of the ring combustion chamber 13

4, 5

outlet openings

6

combustion chamber

7, 8

Air inlet slot

9

Premixgaszuführöffnungen

10

fuel

11.12

mixture profile

13

annular combustion chamber

Claims (9)

Method for operating an annular combustion chamber (13) with a plurality of circularly arranged premix burners (1, 2), in each of which a fuel-air mixture is generated before it is ignited and used as a hot gas stream to drive at least one turbine stage of a gas turbine system,
characterized in that
at least one premix burner (2) is operated such that the at least one premix burner (2) has a spatial mixture profile (12) within the fuel / air mixture that differs from all other premix burners (1). Method according to claim 1,
characterized in that
at least three premix burners are operated in the manner described above, and that these at least three premix burners (1) are arranged in a circular manner in the annular combustion chamber (13) in a uniformly distributed manner with an equidistant distance from one another. The method of claim 1 or 2,
characterized in that
the spatially deviating mixture profile (12) is generated by a deviating premix gas perforation (9) within the premix burner (2). Method according to one of claims 1 to 3,
characterized in that
the at least one premix burner (2) is operated in such a way that at least one asymmetry is generated within the hot gases emerging circularly from the entirety of all premix burners, which at least effectively reduces the occurrence of combustion comb pulsations. Annular combustion chamber (13) with a multiplicity of circularly arranged premix burners (1, 2) with a premix gas perforation (9) inside the premix burner (1, 2), for driving a gas turbine,
characterized in that
at least one premix burner (2) has one of all other premix burners (1) at least one area in the premix gas perforation (9) in which adjacent openings of the premix gas perforation (9) are at a different distance from one another than in the rest of the premix gas perforation (9). Annular combustion chamber (13) according to claim 5,
characterized in that
all other premix burners (1) have a uniformly distributed premix gas perforation (9). Annular combustion chamber (13) according to claim 5 or 6,
characterized in that
in the case of the at least one premix burner (2) within the premix burner (2), the openings of the premix gas perforation (9) arranged downstream have a greater mutual distance than upstream. Annular combustion chamber (13) according to claim 5 or 6,
characterized in that
in the at least one premix burner (2) within the premix burner (2), the openings of the premix gas perforation (9) arranged upstream are at a greater mutual distance than downstream. Annular combustion chamber (13) according to one of Claims 5 to 8,
characterized in that
at least three premix burners are designed in the above manner and that the at least three premix burners are arranged in a circular, uniform distribution around the annular combustion chamber (13).

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