SYSTEM AND METHOD FOR ONLINE MONITORING OF CORROSION OF GAS TURBINE COMPONENTS

• US 20110027063A1
• Filed: 07/30/2009
• Published: 02/03/2011
• Est. Priority Date: 07/30/2009
• Status: Active Grant

• Current Assignee: GE Infrastructure Technology, LLC (General Electric Company)
• Original Assignee: General Electric Company
• Inventors: Czapiewski, Jeff P., Hefner, Rebecca
• Granted Patent: US 8,475,110 B2
• Time in Patent Office: Days
• US Class Current: 415/1
• CPC Class Codes: G01N 17/02 Electrochemical measuring systems for weathering, corrosion or corrosion-protection measurement

Abstract

A system and method capable of performing online corrosion monitoring of a component installed in a gas turbine. A sensing device is located so that electrodes thereof are exposed to an operating environment within the gas turbine section containing the component. The electrodes are formed of a material so that the component and electrodes similarly respond to corrosive agents within the gas turbine section. The electrodes are electrically insulated from each other and each electrode is operable as an anodic electrode or a cathodic electrode, depending on the extent of corrosion thereat, so that each electrode has an electrical potential value, voltages exist across the electrodes, electric currents flow between the electrodes, and the electrical potential/current values correspond to corrosion behaviors at the anodic electrodes. During gas turbine operation, output signals are obtained from the sensing device and indications are provided as to when certain maintenance operations should be performed on the gas turbine.

Claims

1. A method for online monitoring of corrosion of a component installed in a section of a gas turbine, the method comprising:

locating a multi-electrode array sensing device on the gas turbine so that electrodes of the sensing device are exposed to an operating environment within the section of the gas turbine, the electrodes being formed of an electrode material and the component being formed of a component material that respond to at least one corrosive agent within the section of the gas turbine, the electrodes being electrically insulated from each other and each electrode being operable as an anodic electrode or a cathodic electrode depending on the extent of corrosion thereat so that each electrode has an electrical potential value, voltages exist across the electrodes, an electrical current flows from each anodic electrode to at least one of the cathodic electrodes, and the electrical potential values and the electric current values correspond to corrosion behaviors at the anodic electrodes;

operating the gas turbine and, while the gas turbine is operating, obtaining output signals from the sensing device based on at least one of the electrical potential values and the electric current values; and

indicating when a maintenance operation should be performed on the gas turbine by using the output signals of the sensing device to predict a corrosion characteristic of the component.

2. The method according to claim 1, wherein the corrosion characteristic is at least one of pitting depth and pitting rate of the component.

3. The method according to claim 1, wherein the corrosion characteristic is pitting depth of the component.

4. The method according to claim 8, wherein the corrosion characteristic is pitting rate of the component.

5. The method according to claim 1, further comprising the step of performing the maintenance operation following the indicating step.

6. The method according to claim 5, wherein the maintenance operation comprises shutdown of the gas turbine and dismantling the component from the section of the gas turbine.

7. The method according to claim 5, wherein the maintenance operation comprises online washing of the section of the gas turbine while the gas turbine is operating.

8. The method according to claim 5, wherein the maintenance operation comprises shutdown of the gas turbine and offline washing of the section of the gas turbine.

9. The method according to claim 1, wherein the electrode and component materials are the same so that the component and the electrodes similarly respond to the at least one corrosive agent.

10. The method according to claim 1, wherein the electrode material is more sensitive to the at least one corrosive agent than is the component material.

11. The method according to claim 1, wherein the section of the gas turbine is the compressor section and the component is a compressor blade.

12. The method according to claim 11, wherein the sensing device is located in a shell wall of the compressor section.

13. The method according to claim 11, wherein the sensing device is located in the compressor blade.

14. A method for online monitoring of corrosion of a compressor blade installed in a compressor section of a gas turbine, the method comprising:

locating a multi-electrode array sensing device in the compressor section so that electrodes of the sensing device are exposed to an operating environment within the compressor section of the gas turbine, the electrodes being formed of an electrode material and the blade being formed of a blade material so that the blade and the electrodes similarly respond to corrosive agents within the compressor section of the gas turbine, the electrodes being electrically insulated from each other and each electrode being operable as an anodic electrode or a cathodic electrode depending on the extent of corrosion thereat so that each electrode has an electrical potential value, voltages exist across the electrodes, an electrical current flows from each anodic electrode to at least one of the cathodic electrodes, and the electrical potential values and the electric current values correspond to corrosion behaviors at the anodic electrodes;

operating the gas turbine and, while the gas turbine is operating, obtaining output signals from the sensing device based on at least one of the electrical potential values and the electric current values;

indicating when a maintenance operation should be performed on the gas turbine by using the output signals of the sensing device to predict a corrosion characteristic of the blade; and

performing the maintenance operation, wherein the corrosion characteristic is at least one of pitting depth and pitting rate of the blade.

15. A system adapted to perform online monitoring of corrosion of a component installed in a section of a gas turbine, the system comprising:

a multi-electrode array sensing device located on the gas turbine so that electrodes of the sensing device are exposed to an operating environment within the section of the gas turbine, the electrodes being formed of an electrode material and the component being formed of a component material that respond to corrosive agents within the section of the gas turbine, the electrodes being electrically insulated from each other and each electrode being operable as an anodic electrode or a cathodic electrode depending on the extent of corrosion thereat so that each electrode has an electrical potential value, voltages exist across the electrodes, an electrical current flows from each anodic electrode to at least one of the cathodic electrodes, and the electrical potential values and the electric current values correspond to corrosion behaviors at the anodic electrodes;

means for obtaining output signals from the sensing device based on at least one of the electrical potential values and the electric current values; and

means for indicating when a maintenance operation should be performed on the gas turbine by using the output signals of the sensing device to predict a corrosion characteristic of the component.

16. The system according to claim 15, wherein the electrode and component materials are the same so that the component and the electrodes similarly respond to the at least one corrosive agent.

17. The system according to claim 15, wherein the electrode material is more sensitive to the at least one corrosive agent than is the component material.

18. The system according to claim 15, wherein the section of the gas turbine is the compressor section and the component is a compressor blade.

19. The system according to claim 18, wherein the sensing device is located in a shell wall of the compressor section.

20. The system according to claim 18, wherein the sensing device is located in the compressor blade.