Techno-economic comparison of energy usage between azeotropic distillation and hybrid system for watereethanol separation D. Kunnakorn a , T. Rirksomboon a , K. Siemanond a , P. Aungkavattana b , N. Kuanchertchoo c , P. Chuntanalerg a , K. Hemra b , S. Kulprathipanja d , R.B. James d , S. Wongkasemjit a, * a The Petroleum and Petrochemical College and the Center for Petroleum, Petrochemicals, and Advanced Materials, Chulalongkorn University, Bangkok 10330, Thailand b National Metal and Materials Technology Center (MTEC), Thailand Science Park, Patumthani, Thailand c Faculty of science, Ramkhamhaeng University, Bangkok, Thailand d UOP, A Honeywell Company, Des Plaines, IL, USA article info Article history: Received 14 February 2012 Accepted 29 September 2012 Available online 26 October 2012 Keywords: Techno-economic analysis Azeotropic distillation NaA zeolite membrane Pervaporation abstract Conventional azeotropic distillation, consuming very high energy, is mostly used to produce high purity ethanol for renewable energy usage. In this study, the techno-economic comparison between azeotropic distillation (distillation followed by practical azeotropic distillation) and hybrid system (distillation fol- lowed by pervaporation system) for producing high purity of ethanol is demonstrated using the Pro II by Provision version 8.0. In the hybrid system, NaA zeolite membrane is used to separate the water from ethanolewater mixture. It is found that the hybrid system is the most effective technique for producing more than 99.4%wt of ethanol with an energy consumption of 52.4% less than the azeotropic distillation. Ó 2012 Elsevier Ltd. All rights reserved. 1. Introduction Although the most widely used technique to produce ethanol is the distillation process, it can only produce ethanol with a purity close to 95%wt owing to the formation of the azeotropic phase between water and ethanol [1,2]. The azeotropic distillation, involving the additional component called “entrainer” to separate water from ethanol by distillation [3], was thus introduced to solve this problem. However, azeotropic distillation is not only an energy-consuming process, but is also environmentally unfriendly, due to the toxicity of the entrainer used [4,5]. Pervaporation tech- nique is the technique used to solve these problems because it consumes less energy and is more environmentally friendly [5,6]. The separation of this technique depends on the diffusion coeffi- cient and relative affinity of each component in a membrane [2,7]. By applying vacuum at the permeate side, it creates a driving force across the membrane to separate one component from the mixture. This technique can overcome the azeotropic composition problem found in the distillation process. Membranes used in the pervaporation system are polymeric, inorganic or ceramic, and mixed-matrix membranes, depending on particular applications [8e11]. Sodium A zeolite membrane is a good candidate for watereethanol separation using the perva- poration system since water can more easily pass through the membrane and go to the permeate side due to the hydrophilicity of the membrane [10e12], resulting in higher purity of ethanol in the retentate side. Although a hybrid systemdthe distillation process followed by the pervaporation techniquedhas proven to be a better way to produce high purity ethanol (higher than 99.5%wt), the techno- economic analysis of this system has not yet been studied. In this article, the techno-economic analysis of the azeotropic distillation using benzene or cyclohexane as an entrainer was explored, comparing it to the hybrid system using the software called PRO II by Provision version 8.0 as a simulation program. Lab-scale per- vaporation system of watereethanol separation using our home- made NaA zeolite membrane was introduced to collect data and simulate the hybrid system. 2. Experimental 2.1. Materials Fumed silicon dioxide (SiO 2 , 390  40 m 2 /g surface area, 0.007 mm average particle size) and aluminum hydroxide hydrate [Al(OH) 3 .xH 2 O, 51 m 2 /g surface area] were purchased from Sigmae Aldrich, Inc., and were used as starting materials. Sodium hydroxide (NaOH), from Lab-Scan Analytical Sciences, was used as * Corresponding author. Tel.: þ66 2 2184133; fax: þ66 202154459. E-mail address: dsujitra@chula.ac.th (S. Wongkasemjit). Contents lists available at SciVerse ScienceDirect Renewable Energy journal homepage: www.elsevier.com/locate/renene 0960-1481/$ e see front matter Ó 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.renene.2012.09.055 Renewable Energy 51 (2013) 310e316