In-situ imaging of particle size distribution in an industrial-scale calcination reactor using micro-focusing particle shadowgraphy

Abstract

We present a novel demonstration of in-situ particle size measurement in a high-temperature, industrial-scale reactor for lime-calcination using micro-focusing particle shadowgraphy in particle-laden flows with volume fraction up to 0.02 and an optical path length of 670 mm. This non-intrusive method was demonstrated to provide reliable in-situ measurement of both particle size distribution (PSD) and sphericity, which are relevant to the performance of a novel cement production technology under development to provide direct capture of process-derived CO2 emissions. The details of the optical diagnosing system and test rig are presented. A previously reported processing algorithm based on image gradient to accurately identify the edges of particles in the focal plane with negligible line-of-sight interference was employed to derive both particle diameter and sphericity in comparison with independent extractive measurements with a commercial Mastersizer. The in-situ measurement revealed the presence of large calcined particle agglomerates under some conditions that were not identified with the extractive measurements. Statistical correlations between particle diameter and sphericity are also reported.