METHOD OF STARTING A STEAM TURBINE

• US 20110146276A1
• Filed: 12/23/2009
• Published: 06/23/2011
• Est. Priority Date: 12/23/2009
• Status: Abandoned Application

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Sathyanarayana, Dileep, Dipalma, Steven
• Application Number:
  US12/646,201
• Publication Number:
  US 20110146276A1
• Time in Patent Office: Days
• US Class Current: 60/646
• CPC Class Codes: F01D 17/145 by means of valves, e.g. for steam turbines valves in general F16K
• CPC Class Codes: F01D 19/02 dependent on temperature of component parts, e.g. of turbine-casing
• CPC Class Codes: F01K 13/02 Controlling, e.g. stopping or starting
• CPC Class Codes: F05D 2270/301 Pressure
• CPC Class Codes: F05D 2270/3032 excessive temperatures, e.g. caused by overheating

Abstract

The present invention has the technical effect of reducing the start-up time associated with starting a steam turbine. Embodiments of the present invention provide a new methodology for reducing the steam-to-metal temperature mismatch present during the start-up of a steam turbine. Essentially, embodiments of the invention may raise the pressure of the steam upstream of an admission valve associated with a High Pressure (HP) section of a steam turbine. The initial high pressure of the steam may reduce the enthalpy of steam, reducing temperature of the steam admitted to the HP section.

Claims

1. A method of starting a powerplant machine, the method comprising:

providing a steam turbine configured for converting steam to a mechanical torque;

wherein the steam turbine comprises an HP section; and

increasing a pressure of steam upstream of an admission valve to a pressure matching range, wherein the admission valve is located upstream of the HP section;

wherein the step of increasing the pressure of the steam decreases a temperature of the steam prior to admission into the HP section.

2. The method of claim 1 further comprising the step of initiating a start-up of the steam turbine if a start-up permissive is satisfied.

4. The method of claim 2 further comprising the step of determining whether a rotor stress is within an acceptable range.

5. The method of claim 4 further comprising the step of maintaining a current load on the steam turbine until the rotor stress is within the acceptable range.

6. The method of claim 5 further comprising the step of decreasing the pressure of the steam upstream of the admission valve.

7. The method of claim 6 further comprising the step of increasing a temperature of the steam in an HP bowl region of the HP section.

8. The method of claim 5 further comprising the step of increasing a temperature of the steam in an HP bowl region of the HP section.

9. The method of claim 8 further comprising the step of decreasing the pressure of the steam upstream of the admission valve.

3. The method of claim further comprising the step of opening the admission valve to allow the steam to enter the HP section.

10. A method of starting a powerplant comprising a steam turbine, the method comprising:

providing a steam turbine configured for converting steam to a mechanical torque;

wherein the steam turbine comprises an HP section and a bypass system;

determining whether a cold start of the steam turbine is requested;

increasing a pressure the steam upstream of an admission valve to a pressure matching range, wherein the admission valve is located upstream of the HP section;

determining whether the steam upstream of the admission valve is within the pressure matching range;

initiating a start-up of the steam turbine if a start-up permissive is satisfied; and

modulating the admission valve such that allow the steam flows into the HP section;

wherein the step of increasing the pressure of the steam decreases a temperature of the steam before steams flows into the HP section.

11. The method of claim 10, wherein the step of increasing the pressure of the steam upstream of the admission valve to a pressure matching range, further comprises the step of modulating a bypass valve of the bypass system.

12. The method of claim 11 further comprising the step of determining whether a rotor stress is within an acceptable range.

13. The method of claim 12 further comprising the step of adjusting a loading rate of the steam turbine until the rotor stress is within the acceptable range.

14. The method of claim 13 further comprising the step of modulating the bypass valve to decrease the pressure of the steam upstream of the admission valve.

15. The method of claim 14 further comprising the step of increasing a temperature of the steam in an HP bowl region of the HP section.

16. The method of claim 13 further comprising the step of increasing a temperature of the steam in an HP bowl region of the HP section.

17. The method of claim 16 further comprising the step of modulating the bypass valve to decrease the pressure of the steam upstream of the admission valve.

18. A system configured for starting a steam turbine, the system comprising:

a steam turbine configured for converting steam to a mechanical torque;

wherein the steam turbine comprises an HP section; and

a control system configured for starting the steam turbine, wherein the control system performs the steps of;

determining whether a cold start of the steam turbine is requested;

increasing a pressure the steam upstream of an admission valve to a pressure matching range, before the steam flows into the HP section, wherein an admission valve is located upstream of the HP section;

determining whether the steam upstream of the admission valve is within the pressure matching range;

initiating a start-up of the steam turbine if a start-up permissive is satisfied; and

opening the admission valve to allow the steam to flow into the HP section;

wherein the step of increasing the pressure of the steam decreases a temperature of the steam prior to admission into the HP section.

19. The system of claim 18, wherein the control system performs the step of modulating a bypass valve of the bypass system to increase the pressure of the steam upstream of the admission valve.

20. The system of claim 19, wherein the control system further performs the steps of:

modulating the bypass valve to decrease the pressure of the steam upstream of the admission valve in order to increase a temperature of the steam in an HP bowl region of the HP section.