Experimental Evaluation of the Concentration Zone Widths in Cane Sugar Crystallization using Data and Image Acquisition

摘要

The crystallization process consists in the solid-liquid separation of organic and inorganic chemicals involving mass transfer of a solute dissolved in a liquid phase to a solid phase. The concentration zone widths let define the equilibrium or saturation line, metastable zone (first and second) and unstable or labile zone, and they are of prime importance for the design of optimal operation of cane sugar processes. This work has the goal to present a novel method to determine experimentally the concentration zone widths for commercial cane sugar (refined) using data and image acquisition approach. Crystal size distribution (CSD) analysis and micrograph sequences were used for determining the stability limits in terms of density. As a main result, we found that the width of the concentration zones (metastable and labile) increases nonlinearly whereas the saturation temperature (cooling) decreases in a range from 70 to 40°C. The results are commented in terms of process operation conditions according to the required information by the cane sugar crystallization industry, in order to have an appropriate control of the supersaturation inside the process.