Method for operating a gas turbine

1. A method for operating a gas turbine which is supplied with natural gas, the method comprising:

measuring, during the operation of the gas turbine, the C 2 + concentration in natural gas that is supplied to the gas turbine; and

operating the gas turbine based on the measured current concentration of C 2 +, said operating comprising, with increasing C 2 + concentration,

reducing a flame temperature, or

reducing a turbine inlet temperature, or

increasing a preheating temperature, or

combinations thereof.

2. A method according to claim 1 , comprising:

measuring the C 3 + concentration in the natural gas during the operation of the gas turbine; and

wherein operating comprises operating the gas turbine based on the measured current C 2 + and C 3 + concentrations.

3. A method according to claim 1 , wherein a control procedure for operating the gas turbine is adapted to the current C 2 + concentration.

4. A method according to claim 1 , comprising:

adapting at least one operating parameter of the gas turbine to the current C 2 + concentration.

5. A method according to at least claim 4 , wherein adapting comprising adapting according to a characteristic diagram in which a characteristic line is indicated for at least one operating parameter that changes based on the C 2 + concentration and that shows the respective operating parameter as a function of C 2 + concentration.

6. A method according to claim 5 , wherein the characteristic diagram for at least one operating parameter that is changed based on the C 2 + concentration contains at least two characteristic lines that are allocated to different C 3 + concentrations.

7. A method according to claim 1 , wherein said reduction of the flame temperature, said reduction of the turbine inlet temperature, or both, is carried out so that:

a reference temperature that is measured at a location subject to flashback remains constant; or

a pollutant emissions value remains constant; or

a position of the flame front remains constant in a combustion chamber of the gas turbine; or

combinations thereof.

8. A method according to claim 7 , comprising:

measuring the reference temperature at a burner or a natural gas injection lance.

9. A method according to claim 7 , wherein the pollutant emissions value comprises a NO x emissions value.

10. A method according to claim 1 , wherein operating the gas turbine based on the current C 2 + concentration comprises operating above a preset control concentration.

11. A method according to claim 10 , wherein the control concentration is approximately 9 to 12 vol. % C 2 + in natural gas.

12. A method according to claim 1 , comprising:

generating a warning signal when the current C 2 + concentration exceeds a preset alert concentration.

13. A method according to claim 12 , wherein the alert concentration is less than the control concentration.

14. A method according to claim 12 , wherein the alert concentration is approximately 7 to 10 vol. % C 2 + in natural gas.

15. A method according to claim 1 , comprising:

generating an emergency signal when the current C 2 + concentration exceeds a preset maximum concentration.

16. A method according to claim 15 , wherein the maximum concentration is approximately at least 16 vol. % C 2 + in natural gas.

17. A method according to claim 1 :

wherein operating the gas turbine based on the current C 2 + concentration comprises operating above a preset control concentration which is approximately 9 to 12 vol. % C 2 + in natural gas; or

comprising generating a warning signal when the current C 2 + concentration exceeds a preset alert concentration which is approximately 7 to 10 vol. % C 2 + in natural gas; or

comprising generating an emergency signal when the current C 2 + concentration exceeds a preset maximum concentration which is approximately at least 16 vol. % C 2 + in natural gas; or

combinations thereof.

18. A method according to claim 1 , wherein measuring the C 2 + concentration comprises measuring with a gas-phase chromatograph, a flame ionization detector, an infrared spectrometer, or combinations thereof.

19. A method according to claim 1 , wherein the gas turbine is part of a power plant.

20. A gas turbine comprising:

a control device configured and arranged to operate a gas turbine;

a measuring device configured and arranged to measure C 2 + concentrations in natural gas supplied to the gas turbine;

wherein the control device operates the gas turbine based on the measured current C 2 + concentration such that, with increasing C 2 + concentration, the control device operates the gas turbine to

reduce a flame temperature, or

reduce a turbine inlet temperature, or

increase a preheating temperature, or

combinations thereof.

21. A gas turbine according to claim 20 , wherein the measuring device is configured and arranged to measure C 3 + concentrations.

22. A power plant comprising a gas turbine according to claim 20 .