Method and system for steam quality monitoring

• US 8,433,526 B2
• Filed: 11/12/2010
• Issued: 04/30/2013
• Est. Priority Date: 11/12/2010
• Status: Active Grant

• Current Assignee: GE Infrastructure Technology, LLC (General Electric Company)
• Original Assignee: General Electric Company
• Inventors: Roy, Binayak, Guo, Tao
• Primary Examiner(s): TSAI, CAROL S W
• Application Number:
  US12/945,680
• Publication Number:
  US 20120123696A1
• Time in Patent Office: 900 Days
• Field of Search: 702/24, 702/85, 738/610.6, 73/290.1, 735/97, 735/99, 73/645.3, 250/227.3, 250/222.2, 250/339.1, 250/339.06, 250/227.11, 250/343, 250/239, 250/345, 250/575, 250/351, 250/216, 250/215, 250/352, 250/573, 250/574, 356/336, 356/342, 356/484, 356/335, 356/328, 356/28.5, 356/343, 356/341, 356/227, 356/339, 356/338, 356/37, 356/72, 481/01, 481/97.R
• US Class Current: 702/24
• CPC Class Codes: F01D 21/003 Arrangements for testing or measuring for measuring vibrations G01H
• CPC Class Codes: F22B 35/16 responsive to the percentage of steam in the mixture of steam and water
• CPC Class Codes: G01N 15/0205 by optical means
• CPC Class Codes: G01N 21/534 by measuring transmission alone, i.e. determining opacity

Abstract

A method of determining a steam quality of a wet steam located in an interior of a steam turbine includes emitting from an optical probe a plurality of wavelengths through the wet steam, measuring with the optical probe a wet steam intensity corresponding to each of the plurality of wavelengths emitted through the wet steam, determining an intensity ratio vector by dividing the wet steam intensity by a corresponding dry steam intensity for each of the plurality of wavelengths, successively applying scaling factors to the intensity ratio vector to obtain a scaled intensity ratio vector, calculating a suitable value for each of the scaling factors to obtain a plurality of residuals, determining a minimum residual of the plurality of residuals, determining a droplet size distribution by calculating the droplet number density corresponding to the minimum residual, and determining the steam quality based on the droplet size distribution.

Claims

1. A method of determining a steam quality of a wet steam located in an interior of a steam turbine, the method comprising:

emitting from an optical probe a plurality of wavelengths through the wet steam;

measuring with the optical probe a wet steam intensity corresponding to each of the plurality of wavelengths emitted through the wet steam;

determining an intensity ratio vector by dividing the wet steam intensity by a corresponding dry steam intensity for each of the plurality of wavelengths;

successively applying scaling factors to the intensity ratio vector to obtain a scaled intensity ratio vector;

calculating a suitable value for each of the scaling factors to obtain a plurality of residuals;

determining a minimum residual of the plurality of residuals;

determining a droplet size distribution by calculating the droplet number density corresponding to the minimum residual; and

determining the steam quality based on the droplet size distribution.

2. The method of claim 1, wherein the suitable value is based on the function

3. The method of claim 2, wherein the droplet number density N(D) is constrained to droplets of two diameters.

4. The method of claim 2, wherein the droplet number density N(D) is constrained to droplets of more than two diameters.

5. The method of claim 2, wherein the maximum droplet size D_max is greater than approximately 5,000 nanometers.

6. The method of claim 1, wherein the plurality of wavelengths are generated as white light.

7. The method of claim 1, wherein the plurality of wavelengths comprises greater than approximately 15 wavelengths.

8. One or more non-transitory tangible machine-readable media comprising executable instructions, wherein the executable instructions, when executed by a processor, cause the processor to perform acts comprising:

measuring with an optical probe a wet steam intensity corresponding to each of a plurality of wavelengths emitted through a wet steam;

determining an intensity ratio vector by dividing the wet steam intensity by a corresponding dry steam intensity for each of the plurality of wavelengths;

successively applying scaling factors to the intensity ratio vector to obtain a scaled intensity ratio vector;

calculating a suitable value for each of the scaling factors to obtain a plurality of residuals;

determining a minimum residual of the plurality of residuals;

determining a droplet size distribution by calculating the droplet number density corresponding to the minimum residual; and

determining a steam quality based on the droplet size distribution.

9. The machine-readable media of claim 8, wherein the suitable value is based on the function

10. The machine-readable media of claim 9, wherein the droplet number density N(D) is constrained to droplets of two diameters.

11. The machine-readable media of claim 9, wherein the droplet number density N(D) is constrained to droplets of more than two diameters.

12. The machine-readable media of claim 9, wherein the maximum droplet size D_max is greater than approximately 5,000 nanometers.

13. The machine-readable media of claim 8, wherein the plurality of wavelengths are generated as white light.

14. A steam quality monitoring system, comprising:

an optical emitter configured to emit light at a plurality of wavelengths;

an optical detector configured to detect light at the plurality of wavelengths;

a processor coupled to the optical emitter and the optical detector, and configured to execute instructions stored in a memory or storage device, wherein the instructions, when executed by the processor, cause the processor to perform acts comprising;

detecting with the optical detector a wet steam intensity corresponding to each of the plurality of wavelengths emitted by the optical emitter through the wet steam;

determining an intensity ratio vector by dividing the wet steam intensity by a corresponding dry steam intensity for each of the plurality of wavelengths;

successively applying scaling factors to the intensity ratio vector to obtain a scaled intensity ratio vector;

calculating a suitable value for each of the scaling factors to obtain a plurality of residuals;

determining a minimum residual of the plurality of residuals;

determining a droplet size distribution by calculating the droplet number density corresponding to the minimum residual; and

determining a steam quality based on the droplet size distribution.

15. The steam quality monitoring system of claim 14, comprising a steam turbine, wherein the optical emitter and the optical detector are disposed in an interior of the steam turbine.

16. The steam quality monitoring system of claim 14, comprising a steam quality controller configured to initiate a control function to increase the steam quality if a sensed level is below a threshold level of the steam quality.

17. The steam quality monitoring system of claim 14, wherein the suitable value is based on the function

18. The steam quality monitoring system of claim 17, wherein the droplet number density N(D) is constrained to droplets of two diameters.

19. The steam quality monitoring system of claim 17, wherein the droplet number density N(D) is constrained to droplets of more than two diameters.

20. The steam quality monitoring system of claim 17, wherein the maximum droplet size D_max is greater than approximately 5,000 nanometers.