On-line size measurement of fine dust through digital imaging

On-line continuous particle sizing is important in many industrial applications, such as particulate emission monitoring, drug delivery, painting and so on. For many years, the design and implementation of a low-cost, non-invasive instrument for the on-line continuous monitoring of particulate emission remains a challenge. The on-line size distribution measurement of fine dusts through digital imaging is investigated and discussed in this paper. In order to acquire the particle size information, an on-line imaging system is designed and built up. An ellipse-fitting algorithm is implemented to acquire the equivalent size of a particle from the captured images. The image segmentation is accomplished by thresholding processing and the connected regions in the binary images are successfully identified based on the definitions of 4-connectivity. The statistical analysis on the basis of experimental results is accomplished in order to obtain the particle size distribution and evaluate the imaging system performance. This on-line particle sizing system is tested with narrow classified fractions of natural calcium carbonate.