Automation parameters for milling adjustments during processing of soft canes

Concerns have been raised that many sugarcane varieties in the development pipeline, particularly in the Central and Southern regions, have fibre quality classified as soft, with some soft enough to cause processing problems in the factory. The main issues have been feeding of the cane through the milling train and high bagasse moisture contents causing subsequent combustion issues and low steam pressure at the boiler station. These cane varieties are usually designated as ‘soft canes’. With soft canes in a factory’s cane supply, there is a need to find a way to process them reliably at a reasonable rate, to extract the sucrose and produce reasonable quality bagasse for steam generation. This paper reports on a series of experiments at Isis mill to examine the effect of varying cane preparation, added water rate and added water temperature on the operation and performance of the factory, with the objective of providing the information necessary to develop an automated control strategy for handling the processing of soft canes without manual intervention. Changes to shredder speed to adjust cane preparation and changes to added water rate and temperature affect the operation and performance of the milling train. In particular, changing shredder speed influences #1 mill torque, changing added water rate influences #2 and #5 mill torque, and changing added water temperature influences #5 mill torque. Changing shredder speed and changing added water rate are proposed as strategies to address problems caused by the processing of soft canes.