Method for operating a gas turbine and gas turbine system for carrying out the method

1. A method for operating a gas turbine using a first fuel at full load, the method comprising:

operating the gas turbine during partial load operation with a second fuel instead of the first fuel to achieve an improved emission behavior, with the second fuel having a richer mix of higher-value hydrocarbons with 2 or more carbon atoms per molecule than said first fuel.

2. A method according to claim 1 , wherein the share of higher-value hydrocarbons is approximately 10% to 30% higher in the second fuel than in the first fuel.

3. A method according to claim 1 , wherein the second fuel comprises a fuel selected from the group consisting of ethane (C 2 H 6 ) and propane (C 3 H 8 ).

4. A method for operating a gas turbine using a first fuel at full load, the method comprising:

operating the gas turbine with a second fuel instead of said first fuel to achieve an improved emission behavior, with the second fuel having a richer mix of higher-value hydrocarbons with 2 or more carbon atoms per molecule than said first fuel;

wherein the first fuel and second fuel each comprise gaseous fuel.

5. A method according to claim 4 , comprising:

supplying the first fuel and the second fuel from two separate gas sources, the first fuel and the second fuel having different gas compositions with regard to said higher-value hydrocarbon.

6. A method according to claim 5 , comprising:

supplying the two fuels directly from said gas sources; and

when switching from full load to partial load, switching between a gas source with a low share of higher-value hydrocarbon and a gas source with a higher share of high-value hydrocarbon.

7. A method according to claim 5 , comprising:

generating the two fuels based on a different mixture of the gases from the two gas sources.

8. A method according to claim 4 , comprising:

producing the first fuel from the second fuel, including separating the higher-value hydrocarbon.

9. A method according to claim 8 , comprising:

placing the separated higher-value hydrocarbons in intermediate storage; and

adding said separated higher-value hydrocarbons to the second fuel during partial load operation.

10. A method according to claim 9 , comprising:

liquefying the separated higher-value hydrocarbons prior to intermediate storage;

placing said liquefied separated higher-value hydrocarbons in intermediate storage as liquid gas; and

evaporating said liquefied separated higher-value hydrocarbons prior to said adding.

11. A method according to claim 4 , comprising:

generating the second fuel from the first fuel, including adding higher-value hydrocarbons.

12. A method according to claim 11 , comprising:

taking the added higher-value hydrocarbons from a local reservoir.

13. A method according to claim 12 , wherein the local reservoir comprises a liquid gas storage tank; and comprising:

evaporating liquid gas from the liquid gas storage tank by an evaporator prior to said adding.

14. A method according to claim 12 , wherein the local reservoir comprises a gas reservoir.

15. A method according to claim 4 , comprising:

generating the first fuel and second fuel from a third fuel whose content of higher-value hydrocarbons ranges between those of the first fuel and the second fuel, including either separating the first fuel and the second fuel from the third fuel or adding higher-value hydrocarbons to the third fuel.

16. A method according to claim 15 , comprising:

placing the higher-value hydrocarbons that are separated from the third fuel when generating the first fuel in intermediate storage;

removing higher-value hydrocarbons from said intermediate storage; and

generating the second fuel, including adding said removed higher-value hydrocarbons to the third fuel.

17. A method according to claim 16 , comprising:

liquefying the separated higher-value hydrocarbons prior to said placing into intermediate storage;

wherein said placing comprises placing said liquefied separated higher-value hydrocarbons in intermediate storage as a liquid gas; and

evaporating liquefied separated higher-value hydrocarbons from intermediate storage prior to said adding.

18. A method according to claim 4 , wherein the share of higher-value hydrocarbons is approximately 10% to 30% higher in the second fuel than in the first fuel.

19. A method according to claim 4 , wherein the second fuel comprises a fuel selected from the group consisting of ethane (C 2 H 6 ) and propane (C 3 H 8 ).