Maceration control of a sugar cane crushing mill

Raw sugar is produced from juice in sugar cane crushed by a series of mills. To improve the extraction a liquid bath is applied to the cane between mills. This liquid bath, commonly called maceration, consists of water and some of the produced juice. Although the extraction is improved with higher water content in the maceration, the total juice output is restricted by the storage capacity of the plant. The aim of maceration control is to manipulate the added water within the process limits placed by the storage capacity whilst optimising sugar extraction. In this paper, mathematical models of the processes pertaining to maceration are derived from first principles. A cascaded model predictive controller is then designed using the derived models.