Development of a robust algorithm to compute reactive azeotropes

In this paper, a novel approach for establishing the route for process intensification through the application of two developed softwares to characterize reactive mixtures is presented. A robust algorithm was developed to build up reactive phase diagrams and to predict the existence and the location of reactive azeotropes. The proposed algorithm does not depend on initial estimates and is able to compute all reactive azeotropes present in the mixture. It also allows verifying if there are no azeotropes, which are the major troubles in this kind of programming. An additional software was developed in order to calculate reactive residue curve maps. Results obtained with the developed program were compared with-the. published in the literature for several mixtures, showing the efficiency and robustness of the developed softwares.23339540

Anhydrous ethanol production by extractive distillation: A solvent case study

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Production of anhydrous ethanol in large scale has been made by extractive distillation using conventional solvents like ethylene-glycol. In the present paper, extractive distillation process is studied to obtain pure ethanol using ethylene-glycol and tetra ethylene-glycol as solvents. Residue curve maps are used to analyse the proposed distillation processes in interpreting mixture behaviours and feasibility of distillation columns. The industrial process is simulated at steady state from residue curve map analysis. Simulation results for the ethanol/water mixture using ethylene-glycol, the conventional solvent, and tetra ethylene-glycol, an alternative solvent, are presented. These results showed that the process using tetraethylene-glycol is reliable, although it requires more energy than the process with ethylene-glycol. However, ethylene-glycol has a considerable toxicity level while tetra ethylene-glycol is non-toxic. (C) 2009 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.8816773Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)CNPq [571683/19975 + 141893/2002-8

Application of plate and component efficiency correlations in homogeneous azeotropic distillation processes

In this work, plate and component efficiency correlations have been applied and their performances have been investigated to predict the behavior of extractive distillation columns (homogeneous azeotropic distillation processes). These correlations were developed based on physical and thermal characteristics of the system, as well as on mass and heat transfer mechanisms. The simulation results obtained with the efficiency correlations have been compared with those calculated using the nonequilibrium stage model and also with the experimental data of a pilot-scale extractive distillation column. Very good agreement was obtained. Therefore, it can be concluded that the efficiency correlations are reliable and applicable to extractive distillation processes. The use of these correlations allows the calculations of distillation behavior to be conducted more precisely and with a lower computational burden.45165755576

CLARIFICATION AND PURIFICATION OF AQUEOUS STEVIA EXTRACT USING MEMBRANE SEPARATION PROCESS

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Stevia rebaudiana Bertoni is a native plant from South America and its active constituents have been considered the "sweeteners of the future." Stevia is a natural diet-sweetening source, safe to health and without calories. However, the obtained raw extract is foul smelling, bitter tasting, dark brown colored, and presents suspension matter due to organic and inorganic compounds. Therefore, further purification/clarification is essential in order to get a product of commercial quality. In this work ceramic membranes were applied in the stevia extract clarification process. The process was carried out under different membrane pore sizes and at different pressure values. The best clarification result was obtained with the membrane of 0.1 mu m at 4 bar. On the other hand, the best condition for the flux was obtained with the membrane of 0.2 mu m at 6 bar. The process with all the tested membranes and conditions achieved recovery of sweeteners higher than 90%. Finally, a filtration mathematical model was applied to describe the flux behavior, showing that the main fouling phenomenon during the process occurred because of the complete blocking of pores.323338354Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq