ИСТИНА

Currently more and more attention is paid to the production of renewable energy carriers for example bioalcohols, namely, bioethanol and biobutanol. Due to the nature of the phase equilibrium of dilute water-alcohol mixtures the methods associated with liquid-to-vapor phase transition are widely used for their separation: rectification, gas stripping, liquid extraction, pervaporation. Since fermentation broth is diluted water-alcohol solution with quite low final content of ethanol and especially butanol (7-12 and 1-2 wt.%, respectively) all processes of bioalcohols recovery are high energy consumable. Nowadays an urgent issue is development of bioalcohols recovery processes that can be applied directly during fermentation in order to keep low alcohol concentration in biomedium. Such approach gives two significant profits simultaneously: elimination of inhibition of fermentation process and rising of productivity and yield. The combination of gas stripping and membrane vapor separation is suggested as the most suitable technology for continuous recovery of bioalcohols from fermentation broth. Among other advantages membrane vapor-phase separation method allows to apply water-selective membranes for recovery and concentration of alcohols from dilute aqueous solutions without the need of evaporation of bulk water instead of pervaporation and possibility of achieving of high alcohol concentration in product stream in one stage. The scheme of the vapor-phase membrane separation process with water-selective membranes for bioalcohols recovery from fermentation broth was suggested, mathematical modeling of the process and evaluation of energy consumption were carried out. Obtained results show the importance of liquid-to-vapor phase transition for effective separation in such processes.