Effectiveness of Contact Devices on Ethanol Separation Efficiency in a Packed Distillation Column

Abstract

Aims: To obtain the distillation column efficiency as a function of the packing materials used at various feed compositions of binaries and a ternary system to validate the most effective packing arrangement. Study Design: The design was based on the concentrations obtained from the fermentative production of ethanol.  Place and Duration of Study: Department of Chemical Engineering, Obafemi Awolowo University, Ile-Ife, Nigeria, between December 2009 and August 2010. Methodology: Distillation experiments were carried out with three binary systems (ethanol-water, ethanol-ethylene glycol and water-ethylene glycol) and a ternary system (ethanol-water-ethylene glycol) in a 0.1m internal diameter glass column which was first packed with 8mm diameter Raschig rings (A) thereafter, same size of wire gauze rings (B) and later their combination (C). The experiments were performed under total reflux conditions and at atmospheric pressure. Results: Out of the three packing arrangements investigated, Packing-B showed the best performances with the number of transfer units from 2.8818 to 1.9556 and 4.0723 to 3.0845 corresponding to ethanol-water and ethanol-ethylene glycol binary systems respectively, in the direction of increasing most volatile component (mvc) in the charged compositions. Whereas, for water-ethylene glycol system, opposite trend was obtained. Also, the best efficiencies (0.5652 to 0.9842) were exhibited by Packing-B. The results obtained for the ternary system revealed an inverse relationship between the mvc in the charged composition and the ethanol component efficiencies for all the packing used. This showed that the component efficiencies were higher for Packing-B (3.0157 to 1.5038) than Packing-A (2.7393 to 1.4595) and Packing-C (2.8116 to 1.4721). T-Test showed significantly different efficiencies for only ethanol-water pair-wise comparisons as well as for Packing- A and Packing-B in the ethanol-ethylene glycol system. Conclusion: The designed wire gauze ring packing (Packing-B) has offered higher separation for all the systems examined than the conventional raschig ring. Thus, offering research basis for improving upon locally fabricated packing devices for bio-ethanol industry.