Techno-economic and energetic assessment of an innovative pilot-scale thermosyphon-assisted falling film distillation unit for sanitizer-grade ethanol recovery

Abstract

The increasing demand for ethanol-based disinfectants due to the COVID-19 pandemic has driven the emergence of innovative strategies to avoid the risk of shortage and reduce production costs. Distillation is well-known as the major energy consumer and cost driver for ethanol recovery in conventional distilleries. Our research team has been developing a novel heat-intensified falling film distillation apparatus assisted by a two-phase closed thermosyphon, patented as Destubcal. Therefore, this study aims to provide a techno-economic and energetic assessment of the pilot-scale thermosyphon-assisted falling film distillation unit applied to recover sanitizer-grade ethanol with 70 vol% in alcohol. Performance analysis showed that under a feed flow rate of 14L/h, a feed temperature of 80 °C, and an evaporator temperature of 93 °C, the pilot-scale unit reaches the minimum specific thermal energy consumption with the maximum distillate ethanol recovery and energy efficiency (88.5%). The impact of the elements in the capital cost-share showed instrumentation and control (27.8%), and piping and auxiliary equipment (27.6%) as the predominant capital costs, while the cost for major process equipment represents only 6.2% which reveals a low-cost and easy-to-implement technology. The major operating cost-driver is the labor (51.3%) since the pilot-scale unit has a lower capacity than industrial plants. However, the Destubcal unit spends on utility costs about 31.6$/m3feed, which represents a total saving of 43.8% compared to conventional distilleries. Furthermore, the Destubcal unit saves about 1.78 MJ/kg (46.4%), with 59.2% less column height than a conventional column, being considered techno-economically feasible for sanitizer-grade ethanol recovery.