Rotary kinetic fluid motors or pumps – With passage in blade – vane – shaft or rotary distributor...
Reexamination Certificate
2002-04-11
2004-03-09
Verdier, Christopher (Department: 3745)
Rotary kinetic fluid motors or pumps
With passage in blade, vane, shaft or rotary distributor...
C415S116000, C416S09600A
Reexamination Certificate
active
06702547
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is based on and hereby claims priority to European Patent Application No. 01109036.2, filed Apr. 11, 2001, the contents of which are hereby incorporated by reference.
FIELD OF THE INVENTION
The invention relates to a gas turbine having a number of rotor blades in each case combined into rows of rotor blades and arranged on a turbine shaft, and having a number of stator blades in each case combined into rows of stator blades and connected to a turbine casing.
BACKGROUND OF THE INVENTION
Gas turbines are used in many areas to drive generators or working machines. Here, the energy content of a fuel is used to produce a rotational movement of a turbine shaft. To this end, the fuel is burned in a combustion chamber, compressed air being fed in from an air compressor. The working medium produced in the combustion chamber by the combustion of the fuel and under high pressure and at a high temperature is in this case guided via a turbine unit connected downstream of the combustion chamber, where it is expanded and produces power.
In order to produce the rotational movement of the turbine shaft, in this case a number of rotor blades usually combined into groups of blades or rows of blades are arranged on said turbine shaft, and drive the turbine shaft via a transfer of momentum from the working medium. In order to guide the working medium in the turbine unit, rows of stator blades connected to the turbine housing are additionally normally arranged between adjacent rows of rotor blades.
In the design of gas turbines of this type, in addition to the achievable output, a particularly high efficiency is usually a design objective. On thermodynamic grounds, an increase in the efficiency can in principle be achieved by increasing the outlet temperature at which the working medium flows out of the combustion chamber and into the turbine unit. Therefore, temperatures of about 1200° C. to 1300° C. are aimed at for such gas turbines and are also achieved.
At such high temperatures of the working medium, however, the components exposed to the latter are subjected to high thermal stresses. In order nevertheless, with high reliability, to ensure a comparatively long life time of the components involved, cooling of the components involved, in particular of rotor blades and/or stator blades in the turbine unit, is usually provided. The turbine blades are therefore normally designed such that they can be cooled, the intention being in particular to ensure effective and reliable cooling of the first rows of blades as viewed in the flow direction of the working medium. For the purpose of cooling, the respective turbine blade in this case normally has a coolant duct integrated into the leaf of the blade or the profile of the blade, from which duct a coolant can specifically be fed in, in particular to the thermally stressed zones of the turbine blades.
The coolant used in this case is normally cooling air. This is normally fed to the respective turbine blade via an integrated coolant duct, in the manner of open cooling. Starting from said coolant duct, the cooling air flows through the respectively provided areas of the turbine blade in branching ducts. On the outlet side, these ducts are left open, so that after passing through the turbine blade, the cooling air emerges from the latter and in the process is mixed with the working medium guided in the turbine unit.
In this way, a reliable cooling system for the turbine blades can be provided with comparatively simple means, it being possible even for thermally particularly stressed zones of the turbine blades to be acted on with coolant in a suitable way. On the other hand, however, at the introduction of the cooling air into the working medium guided in the turbine unit, care must be taken that its characteristic parameters, such as pressure and temperature, can be combined with or are compatible with the corresponding parameters of the working medium. In particular, the permissible heating of the cooling air during the cooling of the turbine blades is only limited, so that precisely in the case of comparatively high intended outlet temperatures of the working medium, a particularly large quantity of cooling air is required. This in turn has a limiting effect on the efficiency of the gas turbine.
SUMMARY OF THE INVENTION
The invention is therefore based on the object of specifying a gas turbine of the type mentioned above in which, with reliable cooling of the turbine blades with simple means, a particularly high efficiency can be reached.
According to the invention, this object is achieved in that at least some of the stator blades have an inlet for a cooling medium at their free end facing the turbine shaft.
In this case, the invention is based on the consideration that the gas turbine should be designed for a particularly high efficiency in such a way that reliable cooling of the turbine blades can be carried out with only a low quantity of cooling medium. For this purpose, the cooling of the turbine blades should be carried out in the manner of closed cooling, in which, after flowing through the turbine blade to be cooled, the cooling medium is not mixed with the working medium flowing in the turbine unit but, instead, is led away in a controlled manner and supplied to another use. This is because, in such a cooling concept, no adaptation to the working medium of the operating parameters of the cooling medium flowing away out of the turbine blades is required.
In order to keep particularly low the production and development expenditure for a gas turbine having cooled turbine blades closed in this way, the design should to a large extent follow the design of a gas turbine with open cooling of the turbine blades. The flow paths of the cooling medium in the gas turbine should approximate as far as possible to the flow paths of the cooling medium with open cooling even in the case of closed cooling. This can be achieved in a particularly simple way by the feeding of the rotor blades with cooling air via the turbine shaft and the blade root being maintained but the discharge of the cooling medium from the respective rotor blade being carried out in the manner of closed cooling, likewise through the blade root and into the turbine shaft. From there, the further discharge of the cooling medium is provided via a stator blade adjacent to the respective rotor blades, as viewed in the flow direction of the working medium. To this end, the respective stator blade has an inlet for the cooling medium at its free end facing the turbine shaft. During operation, the respective stator blade therefore has cooling medium flowing through it from its free end in the direction of its blade root in the manner of “countercurrent” flow.
For a particularly beneficial saving effect with regard to the cooling medium needed, and therefore for a particularly high contribution to the increase in efficiency, such closed cooling is expediently provided for the first row of rotor blades, as viewed in the flow direction of the working medium. For this purpose, in an advantageous refinement, those stator blades which form the row of stator blades connected downstream of this row of rotor blades, as viewed in the flow direction of the working medium, have an inlet for the cooling medium at their free end.
On account of the envisaged flow direction of the cooling medium through the respective stator blades, the cooling medium flows out of the respective stator blades into an area of the turbine casing. The cooling medium can therefore be guided away particularly simply in a controlled manner. Accordingly, a gas turbine is in principle suitable both for the use of cooling vapor and also for the use of cooling air as the cooling medium. In this case, cooling air is advantageously provided as cooling medium. On the outlet side, said cooling air can be guided in an area of the front hook of the stator blade and, from there, can be supplied to the combustion again through holes in the stator blade carrier.
In order to provide closed co
Siemens Aktiengesellschaft
Verdier Christopher
LandOfFree
Gas turbine does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Gas turbine, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Gas turbine will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3254317