Dynamic modelling, simulation and optimization of an extractive continuous alcoholic fermentation process

Abstract

The conventional alcoholic fermentation is a typical inhibitory process, leading to low productivity and yield. The ethanol produced inhibits yeast cells, causing a reduction in the alcohol production rate and cell growth rate. In this work, modelling and simulation have shown that continuous extractive fermentation, coupling a fermenter with an extractive vacuum flash chamber, is technically possible. In this case, the ethanol is partially removed, increasing drastically the productivity. Additionally, temperature control can be performed without using heat exchangers. The optimization was carried out using the method of factorial design and response surface analysis, leading to the determination of the most relevant variables, which were: 1.2 h residence time, 0.4 flash recycle rate, 180 g dm−3 sugar concentration and 0.35 cell recycle rate. The results, using optimized variables, were 98% conversion and 23 g dm−3 h−1 productivity, which represent a three times higher productivity than in a conventional continuous process. © 1999 Society of Chemical Industry