Systems and methods to improve shut-down purge flow in a gas turbine system

Patent metadata

Field	Value
Publication number	US-10082090-B2
Application number	US-201615247161-A
Country	US
Kind code	B2
Filing date	Aug 25, 2016
Priority date	Aug 25, 2016
Publication date	Sep 25, 2018
Grant date	Sep 25, 2018

Abstract

A system includes a controller including a memory storing instructions and a processor that executes the instructions. The instructions cause the controller to control a steam turbine system coupled to a power generation system to release steam during deceleration of a gas turbine. The instructions cause the controller to receive a first temperature of the gas turbine and a rotational speed of the gas turbine. The instructions cause the controller to calculate an exhaust flow rate of the power generation system based on at least the first input signal and the second input signal. The instructions cause the controller to control the power generation system to isolate a fuel source from the gas turbine at a portion of normal operating speed of the gas turbine sufficient to achieve a predetermined purging volume during coast down of air flow through the power generation system based on the exhaust flow rate.

First claim

The invention claimed is:

1. A system, comprising:
a controller of a gas turbine and heat recovery steam generator (HRSG) system, comprising:
a memory storing instructions to perform operations of the gas turbine and HRSG system; and
a processor configured to execute the instructions, wherein the instructions, when executed by the processor, cause the controller to:
control a steam turbine system coupled to the gas turbine and HRSG system to release steam to relieve back pressure of a condenser of the steam turbine system during deceleration of a gas turbine of the gas turbine and HRSG system;
receive a first input signal representative of a first temperature at an inlet of a compressor section of the gas turbine and a second input signal representative of a rotational speed of the gas turbine;
calculate an exhaust flow rate of the gas turbine and HRSG system based on at least the first input signal and the second input signal; and
control the gas turbine and HRSG system, during shut-down of the gas turbine and HRSG system, to isolate a fuel source from the gas turbine at a portion of normal operating speed of the gas turbine sufficient to achieve a predetermined purging volume during coast down of air flow through the gas turbine and HRSG system based on the exhaust flow rate.

2. The system of claim 1 , wherein the steam turbine system and the gas turbine and HRSG system are coupled to each other in a single shaft generator system.

3. The system of claim 1 , comprising:
a first temperature sensor that provides the first input signal, wherein the first temperature sensor is positioned at the inlet of the compressor section of the gas turbine; and
a rotational speed sensor that provides the second input signal.

4. The system of claim 1 , wherein the instructions, when executed, cause the controller to receive at least a third input signal representative of a second temperature at an exhaust of the gas turbine or an exhaust stack of an HRSG of the gas turbine and HRSG system, and the exhaust flow rate is based at least in part on the third input signal in addition to the first input signal and the second input signal.

5. The system of claim 1 , wherein instructing the steam turbine system to release steam to relieve back pressure of the condenser of the steam turbine system increases an amount of time for the gas turbine to decelerate below a minimum purging speed of the gas turbine.

6. The system of claim 1 , wherein releasing steam to relieve back pressure of the condenser of the steam turbine system comprises opening a cooling and sealing air system of the steam turbine system, opening a steam valve of the steam turbine system, or both.

7. The system of claim 1 , wherein the instructions, when executed, cause the controller to control the gas turbine and HRSG system to isolate the fuel source when the gas turbine reaches the portion of normal operating speed of the gas turbine sufficient to achieve the purging volume while the gas turbine operates at a rotational speed greater than a minimum purge flow requirement of the gas turbine.

8. The system of claim 1 , wherein relieving the back pressure of the condenser of the steam turbine system reduces drag on the gas turbine.

9. The system of claim 8 , wherein the instructions, when executed, cause the controller to control the steam turbine system to stop releasing steam when the predetermined purging volume is achieved.

10. A method, comprising:
utilizing a controller to:
control a steam turbine system coupled to a gas turbine and heat recovery steam generator (HRSG) system to release steam to relieve back pressure of a condenser of the steam turbine system during deceleration of a gas turbine of the gas turbine and HRSG system;
receive a first measurement of a first temperature of the gas turbine and HRSG system from a first sensor, wherein the measurement of the first temperature comprises at least a temperature at an inlet of a gas turbine of the gas turbine and HRSG system;
receive a second measurement of a rotational speed of the gas turbine from a second sensor;
calculate an exhaust volume flow rate of the gas turbine and HRSG system based on at least the first temperature and the rotational speed of the gas turbine;
obtain a purging volume of the gas turbine and HRSG system that is based on at least a volume of an HRSG of the gas turbine and HRSG system; and
control the gas turbine and HRSG system, during shut-down of the gas turbine and HRSG system, to isolate a fuel source from the gas turbine at a portion of normal operating speed of the gas turbine sufficient to achieve the purging volume during coast down of air flow through the gas turbine and HRSG system based on the exhaust volume flow rate.

11. The method of claim 10 , wherein the first sensor comprises a temperature sensor positioned at an inlet of a compressor section of the gas turbine, and the second sensor comprises a rotational speed sensor of the gas turbine.

12. The method of claim 10 , comprising utilizing the controller to receive a third measurement of a second temperature of the gas turbine and HRSG system via a third sensor, wherein the third sensor comprises a temperature sensor positioned at an exhaust of the gas turbine or an exhaust stack of the HRSG, and calculating the exhaust volume flow of the gas turbine and HRSG system is based on at least the second temperature.

13. The method of claim 10 , comprising utilizing the controller to determine the portion of normal operating speed at which the fuel source is isolated from the gas turbine based at least in part on historical data relating to an amount of time the gas turbine takes to reach a minimum purging speed after isolating the fuel source from the gas turbine.

14. The method of claim 10 , wherein utilizing the controller to control the steam turbine system to release steam to relieve the back pressure of the condenser of the steam turbine system comprises at least one of:
controlling a first valve of a cooling and sealing air system of the steam turbine system to open;
controlling a steam valve of the steam turbine system to open; or
controlling both the first valve and the steam valve to open.

15. A tangible, non-transitory, machine-readable-medium, comprising machine-readable instructions to:
receive a first measurement of a first temperature of a power generation system via a first sensor, wherein the first temperature comprises a temperature at an inlet of a gas turbine of the power generation system;
receive a second measurement of a rotational speed of the gas turbine via a second sensor;
calculate exhaust flow rate of the power generation system based on at least the first temperature and the rotational speed of the gas turbine;
control a steam turbine system coupled in a single shaft arrangement to the gas turbine to release steam to relieve back pressure of a condenser of the steam turbine system during deceleration of the gas turbine of the power generation system; and
control the power generation system, during shut-down of the power generation system, to isolate a fuel source from the gas turbine at a portion of normal operating speed of the power generation system sufficient to achieve a purging volume during coast down of air flow through the power generation system based at least on the exhaust flow rate.

16. The machine-readable-medium of claim 15 , wherein the purging volume is based on at least a volume of a defined portion of the power generation system that comprises a heat recovery steam generator.

17. The machine-readable-medium of claim 15 ,

Assignees

• Gen Electric

Inventors

• Snider David August
• Davis Jr Lewis Berkley
• Alexander Michael Joseph

Classifications

• F05D2270/303

  Temperature · CPC title

• F01D25/002

  Cleaning of turbomachines · CPC title

• F05D2270/54

  by electronic means, e.g. electronic tubes, transistors or IC's within an electronic circuit · CPC title

• F05D2270/306

  Mass flow · CPC title

• F01D21/00 Primary

  Shutting-down of machines or engines, e.g. in emergency; Regulating, controlling, or safety means not otherwise provided for · CPC title