On-line sizing and velocity measurement of particles in pneumatic pipelines through digital imaging

Abstract

This paper presents a new solution to the on-line continuous measurement of particle size and particle velocity within a dilute gas/solid pneumatic pipeline, using low-cost optoelectronic components and imaging hardware. A low-cost, single CCD colour digital camera is used with high power light emitting diodes (LEDs) of different wavelengths, which are driven with very narrow pulses during each camera frame. These resulting frames consist of multiple images of the same particle at different instances in time, by correlating these images it is possible to calculate the size and velocity for each individual particle to high accuracy as the blur due to the finite exposure time can be calculated and removed. As multiple images are taken of the same particle it is possible to extrapolate other information, including acceleration, rotation and direction of movement. The results from this research are very promising and the technique may provide a satisfactory solution to the long standing industrial measurement problem. This system is specifically developed for the measurement of particle sizes in the range of 10μm to 1,000μm, but the technique can be applied equally well to particles outside these limits. © 2007 IOP Publishing Ltd.