Gas turbine plant and method of operation

1. A method for operating a gas turbine plant having a compressor for the compression of combustion air sucked in from the surroundings, a combustion chamber for generating hot gas by the combustion of a fuel with the compressed combustion air, and a turbine, the method comprising:

expanding the hot gas from the combustion chamber to perform work;

measuring temperatures and pressures at various points in the gas turbine plant;

determining the composition of the exhaust gas of the turbine;

deriving a combustion chamber exit temperature from the measured temperatures and pressures and from the determined composition of the exhaust gas of the turbine; and

controlling the gas turbine plant based in part on the derived combustion chamber exit temperature.

2. The method as claimed in claim 1 , wherein measuring temperatures comprises measuring temperatures at the compressor inlet and at the turbine outlet;

wherein measuring pressures comprises measuring the pressure at the turbine outlet and at least one of the pressures at the compressor outlet, at the entrance of the combustion chamber, at the exit of the combustion chamber, or at the turbine inlet; and

wherein deriving comprises deriving from measured temperatures at the compressor inlet and at the turbine outlet and the ratio of one of the measured pressures at the compressor outlet, at the entrance of the combustion chamber, at the exit of the combustion chamber, or at the turbine inlet to the measured pressure at the turbine outlet.

3. The method as claimed in claim 1 , wherein determining the composition of the exhaust gas of the turbine comprises determining the water content of the exhaust gas.

4. The method as claimed in claim 3 , wherein the gas turbine plant further includes means for monitoring the NOx content in the exhaust gas of the turbine, and wherein determining comprises determining the composition of the exhaust gas of the turbine with the monitoring means.

5. The method as claimed in claim 3 , wherein determining the water content in the exhaust gas of the turbine comprises approximately determining the water content from the composition of the fuel and from the size of the fuel mass flow.

6. The method as claimed in claim 5 , comprising directly measuring the fuel mass flow.

7. The method as claimed in claim 5 , further comprising:

regulating the fuel mass flow with a regulating valve;

monitoring the position of the regulating valve; and

calculating the fuel mass flow from the position of the regulating valve.

8. The method as claimed in claim 5 , further comprising:

measuring the initial power of the gas turbine plant; and

calculating the fuel mass flow from the measured initial power.

9. The method as claimed in claim 3 , further comprising:

determining the water content of all the mass flows flowing into the working medium of the gas turbine plant; and

wherein determining the water content of the exhaust gas of the turbine comprises determining based on the determined water content of all the mass flows flowing into the working medium of the gas turbine plant.

10. A gas turbine plant comprising:

a compressor configured and arranged to compress combustion air sucked in from the surroundings;

a combustion chamber in communication with the compressor, configured and arranged to generate hot gas by the combustion of a fuel with the compressed combustion air;

a turbine in communication with the combustion chamber, configured and arranged to expand hot gas from the combustion chamber to perform work;

first means for the measurement of temperatures and pressures at points in the gas turbine plant;

second means for determining the water content in the exhaust gas of the turbine; and

a control connected to the first means and to the second means, the control configured and arranged to derive a combustion chamber exit temperature from the measured temperatures and pressures and water content of the exhaust gas, and to control the gas turbine plant based in part on the derived combustion chamber exit temperature.

11. The gas turbine plant as claimed in claim 10 , wherein the compressor includes an inlet and an outlet, the turbine includes an inlet and an outlet, the combustion chamber includes an entrance and an exit, wherein the first means comprises measurement points positioned for measuring the temperature at the compressor inlet and the temperature and pressure at the turbine outlet, and at least one measurement point positioned for measuring one of the pressures at the compressor outlet, at the entrance of the combustion chamber, at the exit of the combustion chamber, or at the turbine inlet.

12. The gas turbine plant as claimed in claim 10 , wherein the second means comprises an analysis device configured and arranged to analyze the exhaust gas of the turbine.

13. The gas turbine plant as claimed in claim 10 , wherein the second means comprises means for determining the fuel mass flow.

14. The gas turbine plant as claimed in claim 13 , wherein the means for determining the fuel mass flow comprises a throughflow measurement device arranged in the fuel supply.

15. The gas turbine plant as claimed in claim 13 , further comprising:

a regulating valve arranged in the fuel supply; and

wherein the means for determining the fuel mass flow comprises a device configured and arranged to detect the position of the regulating valve.

16. The gas turbine plant as claimed in claim 13 , further comprising:

a generator having terminals, the turbine configure to drive the generator for generating electrical power; and

wherein the means for determining the fuel mass flow comprises a power measurement device at the generator terminals.

17. The gas turbine plant as claimed in claim 10 , further comprising:

points in the gas turbine plant at which a supply of water into the working medium of the gas turbine, discharge of water, or both, can be made; and

wherein the second means comprises water measurement devices at the points.

18. The gas turbine plant as claimed in claim 13 , wherein the second means further comprises means for determining the fuel composition and the influence of the fuel composition on the exhaust gas composition.

19. The gas turbine plant according to Claim 10 :

wherein said combustion chamber is a first combustion chamber downstream of the compressor;

wherein said turbine is a first turbine downstream of the first combustion chamber;

further comprising a second combustion chamber downstream of the first turbine; and

further comprising a second turbine downstream of the second combustion chamber;

wherein the first combustion chamber and the second combustion chamber each have an annular configuration; and

wherein the second combustion chamber is configured and arranged to operate as an autoignition combustion chamber.

20. The method as claimed in claim 3 , wherein determining the water content of the exhaust gas comprises measuring the water content of the exhaust gas.