Retrofit energy integration for selective fermentation in cane sugar mills under hot/cold energy availability

Selective fermentation of reducing sugars in mixed saccharides is an emerging key technology for productivity enhancement utilizing high-yielding sugarcane cultivars in cane sugar mills coproducing sugar, ethanol and electricity. In this paper, a sophisticated analysis on the heat exchanger networks for inlet and outlet of selective fermentation is performed. As a key constraining parameter, the effect of availability of hot/cold heats at cane sugar mills on energy use, investment efficiency and process complexity were examined. The results demonstrated that no additional fuels are needed for implementing selective fermentation into cane sugar mills by utilizing bagasse as fuel. The heat exchanging between process streams should be incorporated to save main steam and initial cost for temperature control for selective fermentation. Cold heat acquisition has a high impact on the final decision in the choice of precooling and heating units.