Crystallization Process in the Sugar Industry: A Discussion On Fundamentals, Industrial Practices, Modeling, Estimation and Control

The sugar industry plays a crucial role in numerous economies worldwide, and projections indicate an increase in sugar demand in the coming years. Sugar manufacturing is a complex and highly energy-demanding process, encompassing various sub-processes, including the milling of sugarcane, clarification of raw cane juice, evaporation of syrup, crystallization of syrup, and centrifugation. The crystallization process involves extracting solid sucrose crystals from a supersaturated solution, with supersaturation being a crucial variable. Most previous review articles have focused on specific topics of the crystallization process in the sugar industry. This review aims to provide a broader and updated discussion. It explores various aspects, such as the fundamentals of the process in the sugar industry, a technological description of the three-stage operation, and an analysis of the role of supersaturation. The review examines the main process variables, the most commonly used industrial sensors, and their limitations. Additionally, it discusses the main proposals and approaches found in the literature related to monitoring, modeling, and control of crystallization in the sugar industry. The article identifies and analyzes some limitations present in the literature, including the selection of instruments for industrial monitoring, confusing references to supersaturation sensors, and the need for proper error analysis in the design of process-focused estimators. In particular, there is an emphasis on including information about error bounds for supersaturation estimators.