EP0710797B1 - Method and device for operating a premix burner - Google Patents

Description

Technical field

The invention relates to a method and an apparatus for Operation of a premix burner, in particular an agent vortex breakdown stabilized double cone type burner, which operated in particular with gaseous fuels and preferably used in gas turbine combustors becomes. The device relates to the fuel supply.

State of the art

With premix burners, such as the double-cone burner according to EP 0 321 809, the aerodynamic phenomenon of vortex breakdown used to recirculate the hot exhaust gases and thus the fuel / air mixture for a low-pollutant Stabilize combustion. A vortex breakdown arises when an axially symmetrical, forward spreading vortex becomes unstable and a backflow zone in the axis creates.

The premix burners are used for typical gas turbine operations Usually designed so that their fuel / air ratio the lowest NOx emissions when operating under Full load delivers. You will therefore be close to the lean extinguishing limit operated, their control range is very limited.

At partial load of the gas turbine or with a lower fuel supply it is therefore necessary to maintain combustion, turn off individual burners so the rest Burners can continue to operate stably or it the combustion air mass flow must be reduced.

An increase in the area of flame stability would Necessity or the required accuracy of such Reduce measures while reducing the performance of the gas turbine increase considerably.

One way to expand the stability range of the The premix burner is the additional one that is located close to the axis Injection of pilot gas so that the fuel gases are enriched.

For the optional operation of a burner with gaseous or liquid fuel, a method is known in which the fuel oil used as an alternative to the pilot gas by injection is atomized by air near the axis of the burner. The air injection also takes place during pilot operation with gas, in which but no atomization is necessary. This extra air destabilizes the pilot gas flame and sets the lean one Extinguishing limit of the flame down. That is why a procedure and a device for operating a combined burner developed for liquid and gaseous fuels, at which atomizes the liquid fuel in one Airblast nozzle and the gaseous fuel inside the burner near the axis of the burner by feeding Pilot gas is enriched, in which the inflow of fan air is controlled in the burner interior. This is how it works with gaseous fuel the inflow of fan air throttled into the burner interior, for example by introducing pilot gas into the blower air.

DE-A-43 06 956 describes a fuel supply for a vortex breakdown stabilized low pollutant premix burner, especially one Double cone burner known in which the main gas pipe for the gaseous Fuel is integrally connected to the burner and a fuel lance Supply means for pilot gas and pilot air and with a supply channel for Liquid fuel is arranged in the main gas pipe. The fuel lance serves the Injection of gaseous and liquid fuels in the center of the Double cone burner. The disadvantage of this solution is that the fuel is cold in the Burner enters and does not react with the air. If liquid fuel is used, so it is mixed with the air and atomized before being injected into the burner. Also there is no reaction between fuel and air within the lance.

WO 93/10400 describes the use of a catalyst in a gas turbine burner. For this purpose, a separate partial oxidation reactor is used to control the pilot gas, e.g. B. methane, in a fuel with a low calorific value, for. B. H ₂ or CO to convert.

Presentation of the invention

The invention tries to avoid all these disadvantages. you the task is based on a vortex breakdown stabilized, operated with gaseous fuels Premix burner for a gas turbine combustor with simple Means to enlarge the area of flame stability, so that the premix burner can also be used without problems under partial load conditions or in the case of very lean main fuel / combustion air mixtures is working.

According to the invention, this is the case with a method according to the preamble of claim 1 achieved in that the Pilot gas / air mixture at one inside the fuel lance arranged at the top of the burner arranged catalyst is ignited and burned there and the hot gas flow then the colder main burner flow inside the burner is added.

According to the invention, this is for a fuel supply for a low-pollutant stabilized by vortex breakdown Premix burner, in particular a burner of the double cone type, achieved according to the preamble of claim 4, that the supply means for the pilot gas and the pilot air are connected to a jet pump arranged in the fuel lance to form a pilot gas / air mixture and that at the end of the fuel lance at the burner tip Catalyst ring-shaped between the feed channel for the liquid fuel and the main gas pipe for igniting and burning the supplied pilot gas / air mixture is arranged.

The advantages of the invention include that the area of flame stability for one by means of vortex breakdown stabilized premix burner towards lean Fuel / air mixtures are shifted and the efficiency the plant is increased. The catalyst sets the Combustion without NOx generation in progress and the resulting hot flow mixes with the colder main burner flow. This delays a further homogeneous reaction. The catalytic ignition is therefore stabilized with a hot flow flame connected.

Another advantage of the invention is that Because of the arrangement of the catalyst in the interchangeable Fuel lance also replaced the catalytic converter very quickly if operational safety problems occur. In addition, a fuel lance can already work for you burner in operation in a gas turbine plant can be easily retrofitted with the catalyst.

It is particularly useful if the pilot gas is under pressure by means of a jet pump integrated in the fuel lance is introduced and its pressure energy is used to a sufficient amount of combustion air from the plenum outside the burner hood into the fuel lance and pre-mix it with the pilot gas, because that’s one good mixing of pilot fuel and combustion air achieved and a cheap high pressure combustion of the gaseous Fuel / air mixture is reached.

It is also advantageous if the combustion air Fuel lance is swirled because it also causes the mixing between pilot fuel and combustion air takes place better.

Finally, there are advantages between the catalyst and the feed channel for the liquid fuel or between the Catalyst and the main gas channel cooling annuli arranged. This will overheat the catalytic converter and the fuel lance or the burner prevented.

It is also expedient if an active catalyst, preferably palladium oxide PdO, platinum, metal oxide mixtures or barium hexaaluminates can be used, being the catalyst support a honeycomb body with a suitable cell density or Pellets can be used.

Brief description of the drawing

In the drawing is an embodiment of the invention using a double-cone type premix burner for one Gas turbine combustor shown.

Fig. 1

einen Teillängsschnitt der Brennkammer und des Doppelkegelbrenners;

Fig. 2

einen vergrösserten Teillängsschnitt des Doppelkegelbrenners im Bereich der Kegelspitze und der Brennstofflanze;

Fig. 3

einen vergrösserten Teillängsschnitt der Brennstofflanze im Düsenbereich;

Fig. 4

einen Teilquerschnitt gemäss Fig. 3.

Show it:

Fig. 1

a partial longitudinal section of the combustion chamber and the double cone burner;

Fig. 2

an enlarged partial longitudinal section of the double-cone burner in the region of the cone tip and the fuel lance;

Fig. 3

an enlarged partial longitudinal section of the fuel lance in the nozzle area;

Fig. 4

3 a partial cross section according to FIG. 3.

It is only essential for understanding the invention Elements shown. The direction of flow of the media is marked with arrows.

Way of carrying out the invention

The invention is described below using an exemplary embodiment and the drawings explained in more detail.

Fig. 1 shows a partial longitudinal section of a gas turbine combustion chamber 1 with a premix burner 2. This premix burner is a low-pollution double-cone burner, which in its basic structure described for example in EP-B1-0 321 809 becomes. It essentially consists of two hollow Partial conical bodies complementing a body with tangential ones Air inlet slots, the central axes of the Partial cone body widening in the direction of flow Have a taper and offset in the longitudinal direction to each other run. The two partial cone bodies each have one Fuel line 3 for supplying the main gaseous fuel 4 on which of the through the tangential air inlet slots flowing combustion air 5 is mixed.

The combustion air 5 is used before mixing with the Main fuel gas 4 as cooling air from the combustion chamber 1. This collects then in turn within the burner hood 6 located plenum 7 before starting with the main fuel is mixed. The mixture formation with the combustion air takes place directly at the end of the air inlet slots.

The fuel lance 8 is easily exchangeable and contains supply means 9 for the gaseous pilot fuel 10, supply means 11 for a possibly usable liquid fuel 12 through a nozzle 13, for example a swirl nozzle or a pressure atomizer into the burner interior 14 is dusted, and feed means 15 for from a plenum 16th pilot air 17 supplied outside the burner hood 6.

2 shows an enlarged view for a more precise illustration Partial longitudinal section of the double cone burner in the area of the cone tip and the fuel lance.

The main fuel 4 flows in the feed line 3 in the Double cone burner and mixes with the combustion air 15, which are formed by the partial cone bodies 18, 19 Air inlet slots 20 in the burner interior of the double-cone burner 2 flows. Ignition of the fuel / air mixture occurs only at the top of the backflow zone, so that there is a stable flame front. The flame strikes not back inside the burner.

Within the fuel lance 8 is at the top of the cone arranged a catalyst 21 according to the invention. He is is annular between the feed channel 11 for liquid fuel 12 and the feed channel 3 for the main fuel 4. Upstream of the catalyst 21 is a jet pump 22 in the Fuel lance 8 arranged. By means of this into the fuel lance 8 integrated jet pump 22 becomes the pilot gas 10 introduced into the lance under pressure. At the same time, his Pressure energy used a sufficient amount of pilot air 17 to be introduced from the plenum 16 outside the burner hood 6 and mix it well with the pilot fuel. By Installation of vortex elements in the feed channel 15 of the pilot air 17 a further advantageous mixing can be achieved become. The pilot fuel / air mixture 25 then flows to the catalyst located at the top of the double cone burner 21 to. The catalyst now initiates the combustion, whereby Hardly measurable NOx emissions arise. The through the Hot gas flow generated by the catalyst mixes in the interior of the burner 14 with the colder main burner flow and improved thereby the stability of the main flame.

The area of flame stability is expanded significantly, by catalytic ignition with hot gas flow flame stabilization is linked.

As can clearly be seen from FIGS. 2 to 4, there are between the catalyst 21 and the feed channel 11 for one possibly used liquid fuel 12, as well as between the Catalyst 21 and the feed channel 3 of the main gas 4 narrow Cooling ring spaces 23 arranged. These are used to prevent overheating to prevent the catalyst 21 and the fuel lance 8.

A material is used as the catalyst 21, which a the highest possible catalytic activity with sufficient thermal Stability guaranteed. It is particularly advantageous the use of palladium oxide PdO as catalyst 21 because it is the most active material for igniting methane oxidation is.

Of course, in other embodiments also other thermally stable, compared to PdO catalytic somewhat less active materials are used, for example Platinum, metal oxide mixtures (such as perovskite, spinels) or barium hexaaluminate.

4 shows a possible structure of the catalyst carrier refer to. The catalyst 21 is in a honeycomb body 24 arranged, the cell density of the honeycomb body 24 different Stress conditions can be adjusted. The design must be such that a sufficiently large one Catalyst area is available.

The catalyst 21 can be replaced quickly and easily become. In addition, the fuel lances 8 can already be existing burner 2 well with this catalyst 21 and the Retrofit jet pump 22.

The previous embodiment referred to a burner 2, which is operated with gaseous fuels 4, 10. However, the invention can also be used for combined operation or for operation with liquid fuel 12. Then the introduction of pilot gas 10 into the fuel lance 8 not necessary, but this will be 22 additional with the jet pump Air 17 pumped in, for example, at part-load operation in addition to atomizing the liquid fuel 12 can be used. However, the catalyst then has 21 lost its actual function; but it bothers not even the operational process.

Reference list

1

Combustion chamber

2nd

burner

3rd

Fuel line

4th

main gaseous fuel

5

Combustion air

6

Burner hood

7

Plenum inside the burner hood

8th

Fuel lance

9

Feeding agent for gaseous pilot fuel

10th

gaseous pilot fuel

11

Liquid fuel supply means

12th

liquid fuel

13

jet

14

Burner interior

15

Feeder for pilot air

16

Plenum outside the burner hood

17th

Pilot air

18th

Partial cone body

19th

Partial cone body

20th

Air inlet slot

21

catalyst

22

Jet pump

23

Cooling annulus

24th

Honeycomb body

25th

Pilot gas / air mixture

Claims (8)

1. Method of operating a low-pollution premixing burner (2) stabilized by means of vortex breakdown, in particular a burner of the double-cone type of construction, with gaseous fuels (4, 10), the main fuel gas (4) being fed to the burner (2) via a main gas tube (3) connected in one piece to the burner (2) and the pilot gas (10) being fed to the burner (2) near the axis of the latter via a separate feed line (9) by means of an exchangeably inserted fuel lance (8), and the pilot gas (10) being mixed inside the fuel lance (8) with air (17) fed from a plenum (16) outside the burner hood (6), characterized in that the pilot-gas/air mixture (25) is fed to a catalyser (21) arranged inside the fuel lance (8) at the tip of the burner (2) and is ignited and burnt there, and the hot gas flow is then mixed with the colder main burner flow in the burner interior space (14).
2. Method according to Claim 1, characterized in that the pilot gas (10) is introduced under pressure by means of a jet pump (22) integrated in the fuel lance (8) and its pressure energy is utilized to introduce a sufficient quantity of combustion air (17) from the plenum (16) outside the burner hood (6) into the fuel lance (8) and to premix this quantity of combustion air (17) with the pilot gas (10).
3. Method according to Claim 2, characterized in that the combustion air (17) is fed to the fuel lance (8) in a swirled fashion.
4. Fuel feed for a low-pollution premixing burner (2) stabilized by means of vortex breakdown, in particular a double-cone burner, the main gas tube (3) for the gaseous fuel (4) being connected in one piece to the burner (2), and an easily exchangeable fuel lance (8) having feed means (9, 15) for pilot gas (10) and pilot air (17) and having a feed passage (11) for liquid fuel (12) being arranged in the main gas tube (3), characterized in that the feed means (9, 15) for the pilot gas (10) and the pilot air (17) are connected to a jet pump (21) arranged in the fuel lance (8) in order to form a pilot-gas/air mixture, and in that a catalyser (21) is arranged at the end of the fuel lance (8) at the burner tip in an annular shape between the feed passage (11) for the liquid fuel (12) and the main gas tube (3) in order to ignite and burn the pilot-gas/air mixture supplied.
5. Fuel feed according to Claim 4, characterized in that annular cooling spaces (23) are arranged between the catalyser (21) and the feed passage (11) for the liquid fuel (12) and between the catalyser (21) and the main gas passage (3) respectively.
6. Fuel feed according to Claim 4, characterized in that active material, preferably palladium oxide, platinum, metal oxide mixtures or barium hexaaluminates, are used as catalyser (21).
7. Fuel feed according to Claim 6, characterized in that a honeycomb body (24) having suitable cell density is used as catalyser carrier.
8. Fuel feed according to Claim 6, characterized in that pellets are used as catalyser carrier.

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