Investigations to mitigate the effects of sucrose degradation and acid formation in factory evaporators on sugar recovery and quality, corrosion and effluent loadings

To remain financially viable Australian sugar milling groups must diversify to cogeneration or other products. Generally, diversification requires that sugar factories increase energy efficiency and reduce steam consumption to generate surplus bagasse, for uses other than sugar manufacture. For sugar factories to achieve this, higher temperatures of process steam are required, larger juice evaporation areas for heat transfer installed and greater quantities of vapour are withdrawn from late in the evaporator set for heating duties. In the case of the Australian sugar factories, which exclusively use Robert evaporators, significant sucrose degradation of up to $1M loss in revenue occurs for a typical steam-efficient factory. Also, the formation of acidic condensates, from the degradation process, results in severe corrosion of pipework, valves, and tube plates. Replacement of these parts occurs every year or so for some mills. Furthermore, the transfer of volatile products, derived from juice degradation, to the cooling water system increases the effluent organic loading and the chemical dosing demand. This project will determine the effects of sucrose degradation and acid formation in factory evaporators on sugar recovery, corrosion and effluent loadings and develop strategies to mitigate these issues.