The Measurement of Particle Concentration Using a Laser Diffraction Particle Size Analyzer.

A laser diffraction particle size analyzer based on the Fraunhofer diffraction theory has the advantages of the real-time measurement of particle size distribution in a broad range. However, the dispersed particle number concentration is not displayed in commercially available analyzers. The method of measuring the dispersed particle concentration was investigated for different particles having various shapes, i. e. spherical, cubical and prismoidal with log-normal distribution by considering the characteristics of the measured voltage of the set detector in relationship to diffracted light intensity.As a result, an approximate equation for the particle concentration was proposed expressing the measured median diameter and the highest voltage measured by the detector. This equation was applicable to particles having various shapes, i. e. spherical, cubical and prismoidal. Furthermore, this technique can be used for the continuous measurement of the particle concentration of growing crystals in the crystallizer for crystallization operation.