Apparatus accurately determining particle size distribution and total concentration in moist sample gas stream, uses laser light pulses of differing intensity to reveal coarse and finest particles down to sub-micron sizes

摘要

Light source (24) intensity can be controlled. An Independent claim is included for the corresponding method of measurement. Dispersed light is evaluated to determine the particle numbers. Illumination with light of differing intensity is used to measure differing bands of particle size. Preferred Features: Two or more sources are included, of differing intensity. The gas flow is illuminated with a succession of controlled (28) pulses of alternating intensity. A single, variable-intensity source can be employed, controlled to similar effect. The source produces white light. Laser(s) are employed. Short pulses of high intensity are alternated with lower intensity light, respective durations being 1 and 2 seconds. In external operation wavelength is 670-680 nm, in moisture-sensing operation it is 320-780 nm. A dryer is connected in the recycle line, following the measurement cell.