Conversion of rye straw into fuel and xylitol: a technical and economical assessment based on experimental data

A contribution to the development of economically sustainable processes to obtain lignocellulosic bioethanol is presented. The simultaneous production of bioethanol and xylitol from rye straw is investigated, as this compound can become a realistic alternative to the transformation of xylose into ethanol. A complete process from the raw material to the end products is developed and simulated with respect to all major operations: hot liquid water pretreatment, fermentation of glucose to ethanol, fermentation of xylose to xylitol, separation and purification of both products. Calculations are based on experimental as well as on literature data. In particular, experimental data about the pretreatment and enzymatic hydrolysis steps previously obtained (Ingram et al., 2009) are used in order to achieve a realistic model that was then implemented using the software Aspen Plus (TM). The optimization of the process energy duties is carried out by means of the pinch technology analysis. Mass balances from the simulation are used in order to size the equipments and calculate the capital investment. Finally production costs and some financial indexes are estimated by an economical analysis. (C) 2010 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.