Development of Steam Quality Measurement and Monitoring Technique Using Absorption Spectroscopy With Diode Lasers

Techniques using a tunable diode laser (TDL) and multiple broadband lasers have been developed and tested for measuring the steam quality or steam wetness fraction. The steam wetness fraction was estimated using a ratiometric technique combining measured absorbance of water and water vapor overtone transitions in the near infrared spectral band. Using these techniques we were able to measure a wide variation in steam quality ranging from saturated steam condition to 80% mass fraction of steam with less than 1% error. Our sensor can be tailor-made to suit cost, sensitivity, and operating conditions as per requirements, and could be used eventually for measuring the quality of steam in the low pressure stage of steam turbines.