Exergetic evaluation of renewable light olefins production from biomass via synthetic methanol

In this paper, an exergetic evaluation was conducted on a two-step biomass-derived light olefins system established using ASPEN PLUS. This system linked methanol synthesis via entrained-flow gasification to a methanol-to-olefins (MTO) process. The mass yield of the system was 0.248 kg light olefins per kg biomass, which is relatively higher than the literature results. The energetic and exergetic efficiencies of this system were 54.66% and 47.65%, respectively. The results of an exergetic analysis indicate that the biomass gasification, steam cycle, methanol separation, CO2 removal and olefins separation produce most of the system inefficiencies. By identifying the occurrence mechanism of the exergy losses, the potential for improvement can be obtained. A further increase of exergetic performance can be obtained from (1) improvement of gasification process via combining biomass torrefaction, and (2) enhancement of energy integration processes via heat network optimization and power generation from the produced steam. (C) 2015 Elsevier Ltd. All rights reserved.