Optical Measurement of Wet Steam in Turbines

Abstract

The wetness fraction of steam causes dangerous erosion of turbine blades and other components, and decreases efficiency of stages. The instrumentation of wet steam has, therefore, attracted growing interest from the point of safety and economical operation of power stations. Based on the light scattering technique, a method is presented that is capable of measuring the wetness fraction of steam, the mean water droplet diameter as well as their full size distribution. An optical probe has been constructed that can be used in the turbines in operation. Its main characteristic and features are discussed in this paper. Experimental results in a 200 MW condensing steam turbine are also given.