OP-II-3

PP-III-49For the exergy analysis, the reference conditions were considered equal to thestandard environmental conditions in Aspen TM (T 0 =298.15 K, p 0 =101.3 KPa). Moleflows, molar fractions and molar enthalpy and entropy of material streams were takenfrom the Aspen TM flowsheet results; each material stream was duplicated andbrought to reference environmental conditions for the evaluation of the referencemolar enthalpy and entropy. Exergy efficiencies of SHF, SSF and SSCF processeswere 85%, 91% and 88% respectively.The heat integration alternatives by pinch analysis were analyzed for SSFprocess. For this purpose, Aspen HX-NET® software was used. Balanced compositecurve was generated and three pinch points were identified (174-169 °C), (168.3-163.3 °C), (35-30 °C). Using thermal pinch diagram and ΔT min =5°C, the targets forminimum heating and cooling utilities requirements were calculated (0 and7.431E+08 kJ/h, respectively). The SSF process can be improvement using thedesign of heat network for thermal integration of the process. The proposed HENreduces cooling utilities by 10.7% and heating utilities by 97.5% (Table 1) andrequires two new heat exchangers.Table 1. Comparison – Network PerformanceRequirements Simulation Base HENHeating Utilities[kJ/h] 5.643E+07 1.419E+06Cooling Utilities[kJ/h] 8.335E+08 7.445E+08Number of Units 17 19References[1]. Wall G. Exergy: a useful concept within resource accounting. Goteborg, Sweden: Institute ofTheoretical Physics, Chalmers University of Technology and University of Goteborg; 1977.[2]. Tomas-Pejo et al. Comparison of SHF and SSF processes from Steam-Exploded Wheat Straw forEthanol Steam-Exploded Wheat Straw for Ethanol Steam-Exploded Wheat Straw for Ethanolcerevisiae Strains. Biotechnology and Bioengineering, 2008.[3]. Wright, J. D. Evaluation of enzymatic hydrolysis processes, Energy from biomass and wastes, Ed.D. L. Klass, 1989.[4]. El-Halwagi, M. M., “Process Integration”, Elsevier, 2006.530