Reduction of process steam demand and water-usage through heat integration in sugar and ethanol production from sugarcane - Evaluation of different plant configurations

The sugarcane industry represents one of the most important economic activities in Brazil producing sugar and ethanol for the internal and external markets. There are also plants dedicated only to ethanol production. The aim of this study is to accomplish a joint assessment to evaluate the reduction of process steam demand and water usage obtained through heat integration and an exergy analysis to quantify the reduction in irreversibility generation owing to heat integration procedure. Two configurations of plant were analysed Case I - all sugarcane juice is destined to produce ethanol without sugar production and Case II - distribution of 50%/50% of total recoverable sugars in sugar and ethanol production. Simulations in ASPEN PLUS® software were performed in order to evaluate the mass and energy balances and heat integration using the Pinch Method was applied in order to minimize the utilities consumption. The results showed that heat integration promoted a reduction in steam consumption of 35% approximately, while the reduction in water consumption (water collecting requirement) was 24 and 13% in comparison to the conventional cases without heat integration.