Steam Quality Monitoring via Spectral Absorption
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Solution Overview
Problem
Existing steam quality monitoring instruments are inaccurate due to the effects of large water droplets, which cause attenuation of optical signals, leading to incorrect steam quality measurements and potential efficiency and erosion issues in steam turbines.
Innovation Solution
A method and system that emit multiple wavelengths of light through wet steam, measure intensity ratios, apply scaling factors to account for droplet size distribution, and calculate steam quality based on droplet number density, using an optical probe and processor to determine accurate steam quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If optical signals are used for steam quality monitoring, then the monitoring can be performed non-invasively, but the accuracy is reduced due to attenuation by large water droplets
Solution Approach 1:
The patent transforms the optical measurement from direct intensity detection to detection of spectral features (absorption lines). By changing the parameter being measured from overall intensity to specific wavelength absorption characteristics, the system becomes insensitive to droplet-induced attenuation while maintaining accuracy in steam quality measurement.
Solution Approach 2:
The patent introduces spectral absorption features as an intermediary measurement mechanism. Instead of directly measuring steam quality through attenuated optical signals, the system uses the absorption spectrum as an intermediate indicator that correlates with steam quality but is not affected by droplet attenuation.
2Measurement precision
If existing optical monitoring instruments are used, then the system is simple to operate, but measurement precision is compromised due to droplet effects
Solution Approach 1:
The system measures spectral absorption features at specific wavelengths rather than overall optical intensity. This parameter change enables accurate steam quality measurement even in the presence of droplets, as absorption line characteristics remain unchanged by droplet attenuation.
3Ease of operation
If optical signals pass through wet steam with large droplets, then the monitoring covers the steam turbine interior, but the signal accuracy deteriorates due to droplet attenuation
Solution Approach 1:
The system shifts from measuring overall optical intensity to measuring spectral absorption characteristics. This parameter transformation preserves measurement accuracy because absorption line positions and shapes are determined by molecular transitions that are unaffected by droplet-induced attenuation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system provides accurate steam quality measurements by reducing the impact of large droplets, improving the assessment of steam quality and turbine performance by aligning with physical predictions, thus enabling better operational decisions.
Implementation Method 1
emitting from an optical probe a plurality of wavelengths through the wet steam
Implementation Method 2
measuring with the optical probe a wet steam intensity corresponding to each of the plurality of wavelengths emitted through the wet steam
Data Source
AI summary
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.