RETRACTED: Production of Pure Ethanol from Azeotropic Solution by Pressure Swing Adsorption
−Pressure swing adsorption (PSA) is attractive for final separation in the process of water removal especially for fuel ethanol production. Despite many researches on simulation and experimental works on adsorption of water on 3A zeolite in a fixed bed, none have studied a process with the actual PSA system. The purpose of this research was to study the PSA process with two adsorbers and effects of several parameters. The research also included analysis of kinetic and thermodynamic data of ethanol-water adsorption on commercial 3A zeolites in a single fixed bed. A two-level factorial design experiment was used in this research work to preliminarily screen the influence and interaction among the factors. Effects of important parameters such as initial temperature, feed concentration and feed rate were investigated. It was proven that the Langmuir isotherm could best predict the experimental results. In the PSA pilot test, the principal factors, which had effects on the performance, were feed rate, feed concentration, adsorption pressure and the cycle time. Prediction of the process efficiency in terms of ethanol recovery and enrichment was proposed in the form of regression models. The results of the study in a fixed bed adsorber could help designing a pilotscale PSA unit. The experiments proved to be successful in terms of producing high concentration ethanol with high percentage of ethanol recovery. With further simulation work the process could be scaled up for an industrial use.
An experimental comparison of type A molecular sieves for drying the ethanol-water azeotrope
Abstract The recovery by adsorption of ethanol from aqueous vapours of composition around that of the azeotrope has been studied using fixed beds packed with various type A molecular sieves. For similar adsorption and desorption conditions, 4A is superior to 3A molecular sieve giving higher capacities, shorter mass transfer zone lengths and greater rates of desorption. Very low water concentrations (
Development of novel algorithm features in the modelling of cyclic processes
We present two novel algorithm features for the transient simulation of cyclic processes that exhibit cyclic steady state (CSS). In principle, the algorithm could be used for many cyclic process. Air separation using rapid pressure swing adsorption (RPSA) is used as an illustration. The first feature of the algorithm is an a priori rational stopping criterion to determine the CSS unambiguously. The stopping criterion ensures that neither is progress towards CSS truncated prematurely nor is computer time wasted by simulating an unnecessarily large number of cycles. The second feature of the algorithm is a reduction of the number of cycles required to reach the CSS while ensuring that the CSS is certainly determined. The conditions where these two novel algorithm features are applicable have been clearly identified. These two features could be employed regardless of the numerical methods used to solve the mathematical models, and regardless of the process in question, as long as certain desired conditions are fulfilled.