Research Of Steam Humidity Measurement System Based On The Light Scattering Theory

Electric energy is an important energy industry in China, which accounts for over 70% of thermal power.Occupies an important position in the thermal power system turbine still has many problems,End-stage of steam turbine exists not only reduces humidity steam turbine operating efficiency,and can cause severe erosion,to turbine security and economy has brought great harm.Therefore,the measurement of steam and humidity has important theoretical and practical significance.To this end, this paper presents a method of light scattering theory-based online real-time measurement of wet steam and conducted experimental studies.(1) First,analysis the influence of humidity in the turbine steam on turbine efficiency,introduce the domestic steam humidity measurement methods;studied the theory of light scattering,light scattering particles occurs through the scattered light signal carries a lot of information scattered particles; study Mie scattering model of spherical particles, combined with Lambert-Beer’s law, obtained as a function of steam humidity and scattered light; before and after comparison of the difference between the scattering scattering got better backscatter measurement theory.(2) Then, after scattering measurements based on the theory, build a simulation test bed, and describes how it works. The experimental system consists of two parts: Part and wet steam measurement part wet steam generation. Wet steam generating device section includes electric boiler, simulate wet steam cylinder; wet steam measurement section includes CCD cameras, lasers, lenses, optical power meter and optical lenses. Describes the working principle of CCD cameras use CCD area array as the optical power of the receiver to receive the scattered light intensity as the basis for the design of the experimental program backscattering measurements and calculations derived steam humidity solving.(3) Finally, the experimental program backscatter measurements in a multi-bench simulation experiments. Set different light intensity, depending on the receiving scattering angles, different positions and different cross-sectional parameters of the experimental conditions to obtain an image of scattered light intensity distribution.The results indicate that backscattering angle becomes larger scattering intensity will slowly weaken through backward scattered light intensity at 30° stronger than the other right for measurement;As the light intensity becomes stronger,the scattering intensity images are significantly strong,at about 20mw the scattering images measurement error is small so suitable for measuring;And wet steam generator in a position near the outlet ends of the image is not clear being not a suitable location,preferably at the near center of the wet steam generator is suitable for measuring,a bit nearer to the enter is the better position to measure. Also get the wet steam droplets radius about 0.96um,humidity 1.1% at one kind of condition,and prove the value after the laser measurement system is feasible.