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ORCID

https://orcid.org/0000-0001-5917-0344

Abstract

This study aimed to design an azeotropic distillation plant using Aspen Plus® V10 software and determine optimal process conditions for producing pure ethanol greater than 95% from pre-concentrated near-azeotropic ethanol-water solution. The non-random two-liquid Redlich-Kwong thermodynamic model was the base method for property analysis and performance prediction. Modelling and simulation of the converged process were conducted for fixed column variables (R = 5, N = 12 and p = 1 atm). Plant operating parameters were varied in the range of 0 to 1 for the pre-heater vapour fraction, 2 to 10 for the column feed plates (NFP), 2 to 6 for the recycle feed plate (NRFP), 10 to 20 kmol/h feed flow rate (FAZ) and 0.81 to 0.86 mol/mol ethanol concentration (XFAZ). Results show that an increase in FAZ and XFAZ resulted in retrograde phenomena, which hinders plant performance while increasing energy requirements. Further, an increase in NFP and NRFP results in a decrease in dehydration plant performance from 99.84% to 97.5%. It was concluded that high energy efficiency and enhanced plant performance are obtained when the plant is operated with FAZ ranging from 18 to 20 kmol/h. The feed and recycle plates should be located closer to the top of the column, i.e., stage 4 for the feed, stage 2 for aqueous solution and stages 1-3 for the recycle streams. The study recommends a careful distillation synthesis followed by real plant monitoring to address the retrograde phenomena effect and improve the overall ethanol dehydration plant performance.

Publisher Name

University of Dar es Salaam

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