Improving the Sensitivity of Forward Light Scattering Technique to Large Particles

Abstract

The detection of a small number of large particles whose size lies outside the required size distribution is important in the processing of many materials when those particles result in the deterioration of the product quality. Laser diffraction, which is a very popular technique for on‐line monitoring and process control, has, however, limited sensitivity to those few large particles. This paper deals with the improvement of this sensitivity. The fluctuations of the signal received by the detectors were analyzed by both experiment and simulation. Two statistical approaches, cross‐correlation and principal component analysis (PCA), were applied. A detection procedure is proposed which is based on the combination of sweep selection through PCA and an appropriate deconvolution of the selected sweeps. The preliminary experiments with Al2O3 powder showed an improved sensitivity to the large particles.

Development and Evaluation of an In-line and On-line Monitoring System for Granule Size Distributions in Continuous Roll Compaction/Dry Granulation Based on Laser Diffraction

“…The scattered light intensity is measured by circular detector plates and used to calculate the size of the particle that would be responsible for this scattering under certain assumptions (e.g., a spherical particle shape) [34]. Laser diffraction is widely used for off-line analytics in batch mode manufacturing, has been intensively studied [35][36][37], and was explored for process monitoring in pharmaceutical applications [26].…”