SIX-ROLL MILL WITH SHAFT MOUNTED ELECTRO-MECHANICAL DRIVES

MOUNTING DEMANDS WERE being placed on the milling tandem at MSF Sugar Limited’s South Johnstone Mill due to a combination of increasing crop size and rising cane fibre levels. Further rate increases were anticipated. An issue of particular concern with the existing tandem was the moisture of the final bagasse and its implications for extraction and boiler operations. South Johnstone chose to install a new, larger final mill as its initial response to this challenge. The new final mill was a six-roll, heavy duty pressure fed mill with rolls 2.55 m long and 1.36 m diameter. The mill was equipped with shaft mounted, variable speed AC, electro-mechanical drives to minimise cost, maximise energy efficiency and allow performance refinements through enhanced control. This mill is the first of its type in Australia to be fitted with shaft mounted electro-mechanical drives. The paper outlines the circumstance faced by the factory, describes the mill installation, documents the performance of the mill over its first two years of operation and describes the ultimately successful attempts to bring the final bagasse moisture from 52% (2014) to 48% (2016).