METHOD AND APPARATUS FOR DETERMINING PARTICLE-SIZE DISTRIBUTION IN A FLOW OF GRANULAR MATERIAL

摘要

1452864 Determining particle size distributions K LESCHONSKI 1 Feb 1974 [1 Feb 1973] 04845/74 Heading G1A [Also in Division G2] The size distribution of particles is determined by injecting them into a flowing carrier fluid (liquid or gas) so that the particles are distributed across the fluid-flow according to their size; the distribution is then found by measuring the absorption of radiation by the particles at different points across the flow. Figs. 1 and 2 show the carrier fluid 2 passing via flow straightening baffles 3 into a measuring zone 4, the particles being injected at 10. Small particles follow path 15 and large ones follow path 14 to form a distribution across the zone. A light source 5, lens 6, apertures 7 and detector 8 are pivoted about point 11 so as to scan across the zone along an arcuate path. The optical assembly is driven by motor 13; the inside of zone 4 is electrically conductive and is earthed to avoid static electricity. The scanning may be replaced by an elongate source; alternatively multiple sources and detectors may be reciprocated across the zone. The measurement may be effected in regions where there are no particles to obtain a measurement of the absorption due to the carrier fluid alone. Gamma rays may be used. The particle size measurement may be used for process control.