Turbine systems and methods for using internal leakage flow for cooling

1. A cooling system for a turbine with a first section and a second section, comprising:

a first line for diverting a first flow from the first section;

wherein the first flow comprises a first temperature;

a second line for diverting a second flow from the first section;

wherein the second flow comprises a second temperature less than the first temperature; and

a merged line for directing a merged flow of the first flow and the second flow to the second section;

wherein the merged flow has substantially a same temperature throughout the length of the merged line.

2. The cooling system of claim 1 , wherein the first line comprises a first valve thereon to prevent a backflow into the first section.

3. The cooling system of claim 1 , wherein the second line comprises a throttling valve thereon.

4. The cooling system of claim 3 , wherein the throttling valve begins to open when the second flow exceeds a predetermined temperature.

5. The cooling system of claim 3 , wherein the throttling valve comprises a variable flow rate therethrough.

6. The cooling system of claim 1 , wherein the merged line comprises a merged line valve.

7. The cooling system of claim 6 , wherein the merged line valve opens when the turbine exceeds a predetermined load.

8. The cooling system of claim 6 , wherein the merged line valve opens when the second section exceeds a predetermined temperature.

9. The cooling system of claim 6 , wherein the merged line valve comprises a hydraulic valve.

10. The cooling system of claim 1 , wherein the merged line comprises a flow orifice thereon.

11. The cooling system of claim 1 , wherein the first flow comprises a leakage flow.

12. The cooling system of claim 1 , wherein the second flow comprises a cold reheat flow.

13. The cooling system of claim 1 , wherein the second flow comprises an endpacking leakage flow.

14. A method for cooling an intermediate pressure turbine section with a leakage flow from a high pressure turbine section of a turbine, comprising:

directing the leakage flow away from the high pressure turbine section;

combining the leakage flow with a reheat flow from the high pressure turbine section to form a combined flow; and

directing the combined flow to the intermediate pressure turbine section, wherein the combined flow has substantially a same temperature from the high pressure section to the intermediate pressure section.

15. The method of claim 14 , wherein the combining step occurs when the reheat flow exceeds a predetermined temperature.

16. The method of claim 14 , wherein the directing the combined flow step occurs when the turbine exceeds a predetermined load.

17. The method of claim 14 , wherein the directing the combined flow step occurs when the intermediate pressure turbine section exceeds a predetermined temperature.

18. The method of claim 14 , further comprising varying a flow rate of the cold reheat flow according to a temperature of the intermediate pressure turbine section.

19. A cooling system for a turbine with a high pressure section and an intermediate pressure section, comprising:

a first line for diverting a leakage flow from the high pressure section;

a second line for diverting a reheat flow from the high pressure section;

a throttling valve positioned on the second line so as to vary a flow rate of the reheat flow; and

a merged line for directing a merged flow of the leakage flow and the reheat flow to the intermediate pressure section;

wherein the merged flow has substantially a same temperature throughout the length of the merged line.

20. The cooling system of claim 19 , wherein the throttling valve begins to open when reheat flows exceeds a predetermined temperature.