Moisture Measurements in a Low Pressure Steam Turbine Using a Laser Light Scattering Probe

Abstract

The paper describes the development of a moisture probe using the principle of laser light attenuation. The probe response was calculated for various droplet sizes and steam conditions. A calibration under known conditions in a special test facility agreed with the predictions for a fog droplet size of 0.2 μm. Using this calibration, measurements were made in a low pressure steam turbine of approximately 500 MW output. Typical distributions of moisture along the blade height are presented.