(285d) Integrated Design of the MixAlco Process for the Conversion of Biomass to Hydrocarbon Fuels

MixAlco is a robust process that converts biomass to fuels and chemicals. To make hydrocarbon fuels, the MixAlco process has the following steps: (1) pretreatment with lime, (2) fermentation with a mixed culture of acid-forming microorganism to obtain carboxylate salts, (3) dewatering with a high-efficiency vapor-compression evaporator, (4) thermal conversion of salts to ketones, (5) hydrogenation of the ketones to mixed alcohols, and (6) oligomerization of alcohols to hydrocarbons using zeolite catalysts. This work focuses on process synthesis, simulation, and integration for optimal designs of the MixAlco process. For the fermentation which is the key feature of the process, reactor design alternatives (steel tank, pile, pond) were compared. The fermentation operating conditions (conversion, residence time, product concentration) that strongly affect the dewatering cost were optimized. Integration was performed at plant-wide level to reduce the fresh usages of raw materials, minimize the demand of steam and power, and determine the strategies of supplying hydrogen for the hydrogenation. Cost estimation for various scenarios was also performed to demonstrate the merits of the integration.