Crystal growth and vacuum pan productivity

The sugar industry in Australia, as in many other parts of the world, has e xpanded rapidly in recent years greatly increasing the burden on processing stations in sugar factories. Consequently, boiling houses and centrifugal stations have often become production bottlenecks, requiring installation o f new equipment, or significant upgrades of existing plant. Meanwhile, of c ourse, sugar quality and recovery must be maintained, which requires (among st other things) optimisation of crystal growth rates, Thus, the SRI embark ed on a rigorous analysis of growth rates, and the effects of factors such as grade of massecuite, stages in the boiling operation and variations in p an design, aiming to establish benchmark figures for factory performance. F urther research has centred on the use of model-based control, using growth equations derived from laboratory and factory experiments to enhance effic iency, and the comparison of such systems with conventional conductivity co ntrol. Productivity gains of 10% are anticipated when model-based control s chemes are applied to batch pans with good circulation and heat transfer pr operties. Important work now underway seeks to determine circulation velocities and f low directions, allowing batch and continuous pan designs to be evaluated q uantitatively, and to validate and refine computational fluid dynamics pred ictions.