Improvements in fermentation and cogeneration system in the ethanol production process: Hybrid membrane fermentation and heat integration of the overall process through Pinch Analysis

The incorporation of an alternative technology for the fermentation process, and an improved cogeneration system in the first-generation ethanol production process were evaluated; and a heat integration analysis was performed as well. The hybrid membrane fermentation, the alternative technology, was considered as a non-conventional operation, and its impact on the overall energy consumption of the integrated process was estimated. The improved cogeneration system contemplated a supercritical cycle, and the increase in surplus electricity was also evaluated assuming a mixture of bagasse and sugarcane straw as fuel. The heat integration of the process streams was performed applying the Pinch Analysis in order to determine the targets for minimum external heating and cooling. Furthermore, the integration of the multiple-effect evaporator of sugarcane juice, to the process, was optimised based on the heat integration analysis results. Moreover, the results showed a possibility of generating a surplus electricity of 138 MW (275 kWh/t of cane) with the new technologies applied.