COMBUSTION CHAMBER OF A GAS TURBINE, GAS TURBINE AND METHOD FOR OPERATING THE SAME

A combustion chamber assembly of a gas turbine, for combusting a fuel in the presence of combustion air, includes: a combustion chamber, in which combustion of fuel occurs; a precombustion chamber upstream of the combustion chamber; an atomization device that feeds a liquid fuel to the precombustion chamber; and a swirl body that feeds combustion air and gaseous fuel to the precombustion chamber. The combustion chamber assembly is configured as a dual-fuel combustion chamber assembly, which, in a gas fuel operating mode, feeds a mixture of a gaseous fuel and combustion air to the combustion chamber via the swirl body, and which, in a liquid fuel operating mode, feeds liquid fuel to the combustion chamber via the atomization device and combustion air to the combustion chamber via the swirl body. The atomization device includes an atomization lance with a central atomization nozzle, and plural decentralized atomization nozzles.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a combustion chamber assembly, having a combustion chamber, of a gas turbine, a gas turbine having such a combustion chamber assembly and to a method for operating such a gas turbine.

2. Description of the Related Art

Gas turbines comprise a combustion chamber and a turbine arranged downstream of the combustion chamber. In the combustion chamber of a gas turbine, a fuel is combusted and hot exhaust gas created in the process. The hot exhaust gas is expanded in the turbine of the gas turbine to extract energy in the process, which can serve for providing drive power in order to, for example, drive a generator for generating electric current. Gas turbines designed as dual fuel turbines are already known from practice. Such dual fuel gas turbines comprise a dual fuel combustion chamber in which in a gas fuel operating mode a gaseous fuel and in a liquid fuel operating mode a liquid fuel are combusted. In the gas fuel operating mode, a mixture of a gaseous fuel and combustion air can be fed to the combustion chamber via a swirl body. In the liquid fuel operating mode, the liquid fuel can be fed to the combustion chamber of the gas turbine via an atomization device and the combustion air via the swirl body.

Thus, there is a need for further improving combustion chambers of a gas turbine formed as dual fuel combustion chambers so that, in particular in the liquid fuel operating mode, the liquid fuel can be more effectively combusted, namely while reducing undesirable exhaust gas emissions such as nitrogen oxide emissions.

SUMMARY OF THE INVENTION

Starting out from the above, an object of the present invention is to create a new type of combustion chamber assembly, including a combustion chamber, of a gas turbine, a gas turbine of such a combustion chamber assembly and a method for operating such a gas turbine.

This object may be attained, in one aspect of the invention through a combustion chamber assembly of a gas turbine in which, the atomization device of which comprises, based on a longitudinal center axis of the combustion chamber or based on a longitudinal center axis of a precombustion chamber of the combustion chamber assembly, a central atomization lance with at least one atomization nozzle. The atomization device, furthermore, comprises multiple, based on the longitudinal center axis of the combustion chamber or based on the longitudinal center axis of the precombustion chamber of the combustion chamber assembly, decentralized atomization nozzles.

Via the central atomization lance, which comprises at least one atomization nozzle, and via the multiple decentralized atomization nozzles, the liquid fuel, in the liquid fuel operating mode, can be optimally introduced into the combustion chamber to ensure effective combustion of the liquid fuel. By way of the central atomization lance, the liquid fuel can be directly introduced into a central recirculation zone within the combustion chamber or the precombustion chamber of the combustion chamber assembly, as a result of which a stable combustion can be achieved. Here, introducing the fuel via the central atomization lance does not take place homogeneously to the combustion air, no premixing of liquid fuel and combustion air takes place here. By way of the decentralized atomization nozzles, the liquid fuel can be homogeneously distributed in the combustion air. Furthermore, a part premixing of liquid fuel and combustion air is achieved via the decentralized atomization nozzle. By way of the decentralized atomization nozzles, exhaust gas emissions, in particular nitrogen oxide emissions, can be reduced compared with the central atomization lance.

According to a further development of the invention, the decentralized atomization nozzles are positioned on a circular path extending about the longitudinal center axis of the combustion chamber or about the longitudinal center axis of the precombustion chamber of the combustion chamber assembly. Preferentially, a center point of the circular path on which the decentralized atomization nozzle is positioned, is positioned on the longitudinal center axis of the combustion chamber or the precombustion chamber of the combustion chamber assembly. Preferentially, a radius of the circular path, on which the decentralized atomization nozzles are positioned, preferably amounts to between 0.4 times and 1.1 times and the inner radius of the swirl body. By way of such decentralized atomization nozzles, with fuel, providing a homogenous distribution of the same with the combustion air and with respect to a premixing of the same with the combustion air can be optimally introduced into the combustion chamber in order to reduce exhaust gas emissions such as nitrogen oxide emissions as much as possible.

According to a further development of the invention, the central atomization lance comprises at least two, preferentially two atomization nozzles, which alone and jointly each provide an atomization cone with a maximum spray angle of 60°, preferentially of maximally 55°. Each of the decentralized atomization nozzles provides an atomization cone with a maximum spray angle of 40°, preferentially of maximally 30°. In this manner, it can be avoided that walls of the combustion chamber and of the precombustion chamber are wetted with liquid fuel. In particular, this serves for the effective combustion of the liquid fuel while the reduction of exhaust gas emissions.

According to a further development of the invention, the central atomization lance, while forming a radial gap, is bounded by an adjoining component radially outside, at least in sections, wherein the combustion chamber can be supplied with combustion air via the radial gap while bypassing the swirl body. When using the central atomization lance for introducing the liquid fuel into the combustion chamber or precombustion chamber of the combustion chamber assembly, an effective combustion of the liquid fuel in the liquid fuel operating mode while reducing in particular nitrogen oxide emissions can also be ensured by this.

According to a first version of the method according to an aspect of the invention, both the central atomization lance and also the decentralized atomization nozzles are utilized in the liquid fuel operating mode throughout the operating range between no load and full load in order to feed the liquid fuel to the combustion chamber. This operating version of the invention is suitable in particular when the gas turbine to be operated is to perform rapid load changes since individual injection nozzles then need not be activated or deactivated. Purging procedures, as are required when switching off individual atomization nozzles, can be avoided in this way. Compared with gas turbines, the combustion chambers of which only have a central atomization lance, exhaust gas emissions can be reduced.

According to a second version of the method according to an aspect of the invention, both the central atomization lance and also the decentralized atomization nozzles are utilized in the liquid fuel operating mode in an operating range below a predetermined load limit in order to feed liquid fuel to the combustion chamber, whereas in an operating range above the predetermined load limit exclusively the decentralized atomization nozzles are utilized in order to feed the liquid fuel to the combustion chamber. This operating version of the invention serves for further reducing exhaust gas emissions, in particular nitrogen oxide emissions. In an upper load range, the central atomization lance for introducing the liquid fuel is not utilized further but the introduction of the liquid fuel in the upper load range takes place exclusively using the decentralized atomization nozzles. Because of this, exhaust gas emissions such as nitrogen oxide emissions can be further reduced namely in the operating range of high loads.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

The invention relates to a combustion chamber assembly of a gas turbine, to a gas turbine having such a combustion chamber assembly and to a method for operating such a gas turbine.

FIG. 1shows a schematic extract from a gas turbine in the region of a combustion chamber1. The combustion chamber1is delimited by a wall2, wherein in the combustion chamber1a fuel is combusted. Exhaust gas generated during the combustion of the fuel in the combustion chamber1can be fed to a turbine100of the gas turbine in order to expand the exhaust gas in the turbine and extract energy in the process.

The combustion chamber assembly is configured as dual fuel combustion chamber assembly, which, on the one hand, can be operated in a gas fuel operating mode and, on the other hand, can be operated in a liquid fuel operating mode.

In the gas fuel operating mode of the combustion chamber assembly, a gaseous fuel is combusted in the combustion chamber1, and a mixture of the gaseous fuel and combustion air is fed to the combustion chamber1, via a precombustion chamber9upstream of the combustion chamber1, via a swirl body3.

The swirl body3is preferentially embodied as radial swirl body and creates a defined swirl of the mixture of combustion air and gaseous fuel entering the precombustion chamber9adjacent the combustion chamber1. The mixture of the gaseous fuel and the combustion air is ignited in the gas fuel operating mode with the help of an electric ignition device, which is not shown.

In the liquid fuel operating mode of the combustion chamber assembly, a liquid fuel is combusted in the combustion chamber1, and the liquid fuel is fed to the combustion chamber1, via the precombustion chamber9, with the help of an atomization device4.

The atomization device4comprises a central atomization lance17which is positioned approximately in the middle of the precombustion chamber9or on a longitudinal center axis20of the precombustion chamber9or on a longitudinal center axis20of the combustion chamber1and injects the liquid fuel in the direction of the longitudinal center axis20into the precombustion chamber9while forming an atomization cone or spray cone8a.

In addition, with respect to the longitudinal center axis20of the combustion chamber1, or of the precombustion chamber9, central atomization lance17, the atomization device4comprises multiple, based on the longitudinal center axis20of the combustion chamber1, or precombustion chamber9, decentralized atomization nozzles18, which can likewise inject the liquid fuel into the precombustion chamber9, namely while forming a respective spray cone8b.

Accordingly, the atomization device4comprises the central atomization lance17and multiple decentralized atomization nozzles18. The central atomization lance17comprises at least one atomization nozzle, preferentially multiple atomization nozzles15,16(seeFIG. 2).

FIG. 2shows a detail of the central atomization lance17of the atomization device4. Between the atomization lance17, which is received in an assembly wall12of the combustion chamber assembly, and an adjoining component5, which is likewise received in the assembly wall12, which follows the atomization lance17of the atomization device4radially outside and which surrounds the atomization lance17of the atomization device4radially outside at least in sections, a radial gap6is formed via which combustion air can be likewise fed to the precombustion chamber9, while bypassing the swirl body3. Accordingly, an arrow13(seeFIG. 1) visualises a flow of combustion air via the swirl body3and an arrow14(seeFIG. 2) a flow of combustion air via the radial gap6between the atomization lance17and the component5, wherein the combustion air flow via this radial gap6is conducted via a swirl body25.

The specific component5, which together with the atomization lance17of the atomization device4provides the annular gap6, is preferentially embodied as a separate sleeve connected to the atomization lance17. In contrast with this it is also possible that the assembly wall12itself defines the component5adjoining the atomization lance17radially outside, which, together with the atomization lance17, defines the radial gap6.

Based on the longitudinal center axis20of the combustion chamber1or precombustion chamber9, the decentralized atomization nozzles8of the atomization device4are preferentially positioned on a circular path19(seeFIG. 3), which extends about the longitudinal center axis20of the combustion chamber1or the longitudinal center axis20of the precombustion chamber9.

A center point of this circular path19, on which the decentralized atomization nozzles18are positioned, is positioned on the longitudinal center axis20in this case. The decentralized atomization nozzles18accordingly surround the central atomization lance17, preferentially concentrically.

FIG. 3shows a radius d18of the circular path19, on which the decentralized atomization nozzles18are arranged. Here it is provided, in particular, that this radius dig of the circular path19, on which the decentralized atomization nozzles18are positioned, amounts to between 0.4 times and 1.11 times an inner diameter d3of the swirl body3. In particular, when the radius d18of the circular path19, on which the decentralized atomization nozzles18are arranged, amounts to between 1.0 times and 1.1 times the inner diameter d3of the swirl body3is the swirl body3at least partly covered by the decentralized atomization nozzles18in its outlet region.

The decentralized atomization nozzles18can also be arranged on multiple preferentially concentric circular paths or on an elliptical path or a polygon.

As already explained, the central atomization lance17of the atomization device4preferentially comprises multiple atomization nozzles, in the exemplary embodiment ofFIG. 2, two atomization nozzles15,16, which are preferentially swirl atomization nozzles. These two atomization nozzles15,16of the central atomization lance17can be supplied with the liquid fuel in the liquid fuel operating mode originating from a common liquid fuel feed21, wherein the fuel conducted from the liquid fuel feed21can be divided into two liquid fuel part feeds21a,21bin order to supply both atomization nozzles15,16of the central atomization lance17with liquid fuel.

The central atomization lance17with both its atomization nozzles15,16sprays in the liquid fuel in the direction of the combustion chamber1with the spray angle α which maximally amounts to 60°, preferentially maximally 55°. In particular when both atomization nozzles15,16of the atomization lance17are jointly operated and also, in particular, when one of these atomization nozzles15,16is operated alone, does the spray angle α amount to maximally 60°, preferentially maximally 55° in each case. Because of this it is ensured that neither walls2aof the precombustion chamber9nor walls2of the combustion chamber1are wetted with liquid fuel, as a result of which a more effective combustion of the liquid fuel can be provided.

As already explained, combustion air can be fed via the gap6to the combustion chamber1, via the precombustion chamber9. The air flow14conducted via this annular gap6serves, on the one hand, for cooling the central atomization lance17of the atomization device4while this air flow14, on the other hand, at least partly surrounds the spray cone8aof the liquid fuel of the atomization lance17on the outside, thus bundling the same.

The specific combustion air14, which can be fed to the combustion chamber1, inFIG. 1, via the precombustion chamber9, while bypassing the swirl body3via the radial gap6, amounts to in particular between 1% and 10% of the combustion air that can be fed to the combustion chamber via the swirl body3.

Here, the combustion air flow14cannot only be fed to the combustion chamber1via the radial gap6in the liquid fuel operating mode but can also be fed via the radial gap6in the gas fuel operating mode, In the gas fuel operating mode the atomization device4, i.e., in particular the atomization lance17of the same, is inactive so that in the gas fuel operating mode no fuel is then introduced via the atomization device4, but is only supplied via the swirl body3.

As already explained, the atomization lance17is orientated centrically, with respect to the longitudinal center axis20; liquid fuel can be introduced into a central recirculation zone via the atomization lance17in the liquid fuel operating mode. Because of this, a very stable combustion can be ensured. Introducing the liquid fuel, based on the longitudinal center axis20, via the central atomization lance17accordingly takes place locally, i.e., not homogeneously to the combustion air, so that no premixing of liquid fuel and combustion air takes place.

As already explained, the combustion chamber assembly, in addition to the central atomization lance17, comprises multiple decentralized atomization nozzles18, which are preferentially arranged on the circular path19. These decentralized atomization nozzles18can be supplied with liquid fuel via a separate liquid fuel feed22(seeFIG. 1), wherein the decentralized atomization nozzles18introduce the liquid fuel into the precombustion chamber9or combustion chamber1approximately in the same direction as the central atomization lance17, however with a spray angle β that is smaller than the spray angle α, wherein the spray angle β of the decentralized atomization nozzles18preferentially amounts to maximally 40°, preferably maximally 30°.

By virtue of the decentralized atomization nozzles18, which are preferentially equally distributed over the circular path19, the fuel, while forming a homogeneous distribution with the combustion air, is introduced into the combustion chamber1, via the precombustion chamber9, while at the same time a part premixing of combustion air and liquid fuel is provided, in particular supported in that the decentralized atomization nozzles18are arranged adjacent to the outlet of the swirl body3. This part premixing can be improved when the radius d18is greater than the radius d3. Accordingly, the radius d18can amount to between 1.0 times and 1.1 times the radius d3.

Preferentially double-jet nozzles or so-called plane jets are utilized as decentralized atomization nozzles18. By way of the decentralized atomization nozzles18a homogeneous supply of the liquid fuel to the combustion air is achieved and furthermore a part premixing of liquid fuel and combustion air.

In particular when the combustion chamber assembly is to be operated in the gas fuel operating mode is a gas-combustion air mixture fed to the combustion chamber1via the swirl body3.

In the gas fuel operating mode, combustion air can likewise be conducted via the annular gap6. The combustion air flow14conducted via the annular gap6is branched off in the region of an air space, of a so-called plenum10, upstream of the swirl body3.

Accordingly,FIG. 1shows an air line11, via which the combustion air can be branched off the plenum10, wherein the combustion air14branched off the plenum10is fed via the air line11to an air chamber7formed by the wall12in order to then, starting out from this air chamber7, to be introduced into the precombustion chamber9via the annular gap6formed between the atomization lance17of the atomization device4and the adjoining component5.

In particular when the combustion chamber assembly is operated in the liquid fuel operating mode with active atomization device4is the liquid fuel fed to the combustion chamber1or precombustion chamber9via the atomization device4, combustion air via the swirl body3and preferentially via the annular gap6between the central atomization lance17and the component5.

In a first advantageous operating mode in the liquid fuel operating mode both the central atomization lance17and also the decentralized atomization nozzles18of the atomization device4are utilized throughout the operating range between no load and full load in order to feed liquid fuel to the combustion chamber1.

For this first operating condition, multiple curve profiles21,22,23and24are shown over the load L of the gas turbine, the curve profile21corresponds to the liquid fuel feed21via the central atomization lance17, wherein the curve profile22corresponds to the liquid fuel feed22via the decentralized atomization nozzles18, the curve profile23shows the load proportion in the total load L, which can be provided by the combustion of the liquid fuel introduced via the central atomization lance17, and wherein the curve profile24shows the load proportion in the total load L that can be provided by the combustion of the fuel that is introduced into the combustion chamber via the decentralized atomization nozzles18.

Accordingly,FIG. 4shows that, in particular when fuel is fed to the combustion chamber1over the entire load range between 0% (no load) and 100% (full load) both via the central atomization lance17and also via the decentralized atomization nozzles18, preferentially a constant quantity of liquid fuel is fed to the combustion chamber1throughout the operating range between no load (0%) and full load (100%) via the central atomization lance (17) (see curve profile21). Then, the power modulation is effected by changing the liquid fuel introduced into the combustion chamber1via the decentralized atomization nozzles (18) (see curve profile22) so that with increasing load demand L the load proportion23of the central atomization lance17compared with the load proportion of the decentralized atomization nozzles18decreases or the corresponding load proportion24of the decentralized atomization nozzles18increases.

According to this operating concept, in which throughout the load range or operating range between no load and full load both the central atomization lance17and also the decentralized atomization nozzles18are utilized to feed the liquid fuel to the combustion chamber it is provided, in particular, that during the acceleration of the gas turbine of the combustion in the combustion chamber1fuel is introduced into the combustion chamber1exclusively via one of the two atomization nozzles15,16of the atomization lance17and that following the acceleration and following the reaching of a defined rotational speed of the gas turbine both atomization nozzles15,16of the atomization lance17are utilized and also to introduce the fuel into the combustion chamber1via the atomization lance17.

As already explained, the fuel quantity provided via the central atomization lance17over the entire operating range and thus load range of the gas turbine according to the operating concept ofFIG. 4is constant, the power modulation is exclusively effected by varying the fuel quantity provided via the decentralized atomization nozzles18. This operating concept is suitable in particular for rapid load changes on the gas turbine since, except for the ignition process, no atomization nozzles will then have to be activated or deactivated. Nor is it required to purge the atomization nozzles after the same have been deactivated. This operating concept serves for a very robust and stable combustion of the liquid fuel. In addition to this, low fuel emissions can be realised, in particular nitrogen oxide emissions of less than 150 vppm based on 15% of oxygen.

FIG. 5illustrates a second operating concept of the combustion chamber assembly according to the invention or of the gas turbine according to the invention comprising the combustion chamber assembly according to the invention. Accordingly,FIG. 5shows that the load range L between no load (0%) and full load (100%) is divided into two load ranges namely into a load range between no load (0%) and a limit value (GW) and into a load range between a limit value GW and full load (100%).

According to the second operating concept ofFIG. 5according to the invention, both the central atomization lance17and also the decentralized atomization nozzles18are utilized in the liquid fuel operating mode in the operating range or load range below the predetermined load limit GW in order to feed liquid fuel to the combustion chamber1. Here, the fuel quantity (see curve profile21) introduced via the central atomization lance17in this load range is preferentially constant, the power modulation in turn is again effected exclusively by changing the liquid fuel quantity introduced via the decentralized atomization nozzles (18) (see curve profile22).

In the load range above the defined limit value GW, the central atomization lance17is deactivated so that no fuel whatsoever is supplied via the same so that in the upper load range between the load limit GW and full load (100%) liquid fuel is then exclusively fed to the combustion chamber1via the decentralized atomization nozzles18.

An advantage of this second operating concept according to the invention consists in that at loads above the defined load limit (GW) the liquid fuel is not centrally introduced into the recirculation zone of the combustion chamber1but exclusively decentralized, so that for the entire introduced liquid fuel a homogeneous introduction to the combustion air and a part premixing with combustion air can be ensured as a result of which exhaust gas emissions, in particular nitrogen oxide emissions can be further reduced compared with the operating concept ofFIG. 4. In particular, nitrogen oxide emissions of less than 90 vppm based on 15% oxygen can be realised