Vent system for use in a gas turbine and method of operating thereof

1. A vent system for use in a gaseous fuel supply circuit of a gas turbine, the gaseous fuel supply circuit including a fuel routing line extending between an insulation valve and a regulation valve coupled downstream from the insulation valve, said system comprising:

a main pipe tapped from the fuel routing line;

a first outlet in downstream flow communication with said main pipe and configured to release gaseous fuel from said main pipe at atmospheric pressure;

a first valve coupled in upstream flow communication with said first outlet;

a second outlet in downstream flow communication with said main pipe and configured to channel the gaseous fuel from said main pipe towards a combustion device;

a second valve coupled in upstream flow communication with said second outlet;

a pressure sensor coupled to the fuel routing line and operable to measure a gaseous fuel pressure therein; and

a control device coupled to said pressure sensor, said first valve, and said second valve, said control device configured in an emergency shutdown phase of the gas turbine to:

open said second valve and close said first valve in response to the measured pressure being above a predetermined value, such that the gaseous fuel in the fuel routing line is routed through said main pipe and through said second outlet; and

close said second valve and open said first valve in response to the measured pressure being below the predetermined value, such that the gaseous fuel in the fuel routing line is routed through said main pipe and through said first outlet.

2. The system in accordance with claim 1 further comprising a third valve coupled in upstream flow communication with said second outlet and in parallel flow communication with said second valve, wherein said control device is further configured in a start-up phase of the gas turbine to selectively open and close said third valve based on a temperature of the gaseous fuel in the supply circuit.

3. The system in accordance with claim 2 further comprising a temperature measurement device configured to measure the temperature of the gaseous fuel, wherein said control device is configured to receive a temperature measurement from said temperature measurement device.

4. The system in accordance with claim 1 , wherein the predetermined value corresponds to a supply pressure for operation of said combustion device.

5. The system in accordance with claim 1 wherein the controller is further configured to close the insulation valve and the regulation valve in the emergency shutdown phase of the gas turbine.

6. The system in accordance with claim 5 further comprising a fourth valve coupled downstream from the regulation valve, wherein said fourth valve is configured to release residual gaseous fuel at atmospheric pressure when said regulation valve is closed.

7. The system in accordance with claim 1 further comprising a gas control valve coupled downstream from said regulation valve.

8. A gas turbine comprising:

a combustor; and

a gaseous fuel supply circuit coupled upstream from said combustor, said gaseous fuel supply circuit comprising:

an insulation valve;

a regulation valve coupled downstream from said insulation valve;

a fuel routing line extending between said insulation valve and said regulation valve;

a main pipe tapped from said fuel routing line;

a first outlet in downstream flow communication with said main pipe and configured to release gaseous fuel from said main pipe at atmospheric pressure;

a first valve coupled in upstream flow communication with said first outlet;

a second outlet in downstream flow communication with said main pipe and configured to channel the gaseous fuel from said main pipe towards a combustion device;

a second valve coupled in upstream flow communication with said second outlet;

a pressure sensor coupled to said fuel routing line and operable to measure a gaseous fuel pressure therein; and

a control device coupled to said pressure sensor, said first valve, and said second valve, said control device configured in an emergency shutdown phase of said gas turbine to:

open said second valve and close said first valve in response to the measured pressure being above a predetermined value, such that the gaseous fuel in said fuel routing line is routed through said main pipe and through said second outlet; and

close said second valve and open said first valve in response to the measured pressure being below the predetermined value, such that the gaseous fuel in said fuel routing line is routed through said main pipe and through said first outlet.

9. The gas turbine in accordance with claim 8 further comprising a third valve coupled in upstream flow communication with said second outlet and in parallel flow communication with said second valve, wherein said control device is further configured in a start-up phase of said gas turbine to selectively open and close said third valve based on a temperature of the gaseous fuel in said supply circuit.

10. The gas turbine in accordance with claim 9 further comprising a temperature measurement device configured to measure the temperature of the gaseous fuel, wherein said control device is configured to receive a temperature measurement from said temperature measurement device.

11. The gas turbine in accordance with claim 8 , wherein the predetermined value corresponds to a supply pressure for operation of said combustion device.

12. The gas turbine in accordance with claim 8 wherein the controller is further configured to close said insulation valve and said regulation valve in the emergency shutdown phase of said gas turbine.

13. The gas turbine in accordance with claim 12 further comprising a fourth valve coupled downstream from said regulation valve, wherein said fourth valve is configured to release residual gaseous fuel at atmospheric pressure when said regulation valve is closed.

14. The gas turbine in accordance with claim 8 further comprising a gas control valve coupled downstream from said regulation valve.

15. A method of operating a gas turbine, the gas turbine including a gaseous fuel supply circuit that includes a fuel routing line extending between an insulation valve and a regulation valve coupled downstream from the insulation valve, said method comprising:

selectively channeling a flow of gaseous fuel from the fuel routing line into a main pipe tapped from the fuel routing line, wherein a first outlet in downstream flow communication with the main pipe is configured to release the gaseous fuel from the main pipe at atmospheric pressure, a first valve is coupled in upstream flow communication with the first outlet, a second outlet in downstream flow communication with the main pipe is configured to channel the gaseous fuel from the main pipe towards a combustion device, and a second valve is coupled in upstream flow communication with the second outlet;

measuring a pressure of the flow of gaseous fuel;

opening the second valve and closing the first valve in response to the gas turbine being in an emergency shutdown phase and the measured pressure being above a predetermined value, such that the gaseous fuel in the fuel routing line is routed through the main pipe and through the second outlet; and

closing the second valve and opening the first valve in response to the gas turbine being in the emergency shutdown phase and the measured pressure being below the predetermined value, such that the gaseous fuel in the fuel routing line is routed through the main pipe and through the first outlet.

16. The method in accordance with claim 15 , further comprising:

selectively opening and closing a third valve in response to the gas turbine being in a start-up phase and based on a temperature of the gaseous fuel, the third valve coupled in upstream flow communication with the second outlet and in parallel flow communication with the second valve.

17. The method in accordance with claim 16 , wherein selectively opening and closing the third valve comprises measuring the temperature of the gaseous fuel with a temperature measurement device.

18. The method in accordance with claim 15 , wherein opening the second valve and closing the first valve in response to the measured pressure being above the predetermined value comprises opening the second valve and closing the first valve in response to the measured pressure being above a supply pressure for operation of the combustion device.

19. The method in accordance with claim 15 , further comprising closing the insulation valve and the regulation valve in the emergency shutdown phase of the gas turbine.

20. The method in accordance with claim 19 , further comprising selectively opening and closing a fourth valve, the fourth valve coupled downstream from the regulation valve and configured to release residual gaseous fuel at atmospheric pressure when the regulation valve is closed.