Design and control of a distillation sequence for the purification of bioethanol obtained from sotol bagasse (Dasylirium sp.)

Abstract

Sotol bagasse (SB) is a byproduct generated during the fermentation of the sotol plant (Dasylirium sp.) for the production of a traditional alcoholic beverage in Mexico. In this study, a novel ethanol purification distillation sequence is proposed, utilizing ethanol produced from SB treatment as described by González-Chavez et al. (2022). Prior to purification, the ethanol-water mixtures exhibited ratios of 0.054 and 0.935. The proposed distillation sequence comprises three columns: i) depletion, ii) extraction (employing ethylene glycol as the solvent agent), and iii) solvent recovery. To assess energy consumption and controllability, three solvent:feed ratios (1.5:1, 2:1, 2.5:1) were examined, taking into account the feed to the second column. The lowest energy consumption was observed at 31 × 103 kW, corresponding to the 1.5:1 ratio. Optimal controllability was achieved at a solvent:feed ratio of 2.5:1, as evidenced by the lowest Integral Absolute Error (IAE) value of 3.3 × 10–3 and the highest proportional gain (Kc) value of 250. In summary, we leveraged previously reported experimental data to design a new distillation sequence with potential applications in the ethanol purification derived from SB fermentation. The outcomes of this investigation underscore the importance of promoting circular economy practices, particularly in the northern region of Mexico, where significant quantities of agrowastes are generated.