In Situ Particle Counting for Research and Industry

Optical methods for particle size distribution measurements in practical high temperature environments have achieved feasibility and offer significant advantages over conventional sampling methods. The present paper describes a mobile prototype optical system which has been designed for general use in a wide range of research and industrial environments. Specific features of this system include a method of providing in situ alignment, and incorporation of an extinction measurement for application to optically thick aerosol flows. The instrument has demonstrated capability for measuring individual particles in the size range 0.25-100 microns at number densities up to lO-^/nW. Frequency distribution measurements of flyash and pulverized coal obtained in an atmospheric combustion exhaust simulator are given in the paper. In addition to demonstration of the system's wide dynamic range, we show the utility of the in situ alignment method in hot (1000K) turbulent flows where beam steering can be a problem.