Estudo do processo de separação das fases biodiesel-glicerina por centrifugação

Abstract

Nowadays the biodiesel is in evidence in the Brazilian Energetic Scenario, which raises the country to a prominent position in investments in renewable energy sources. Natural Substitute of diesel fuel, the biodiesel is made from renewable sources, like vegetable oils, animals or residual fats, by transesterification reaction: reaction between the oil or fat, with excess of methanol or ethanol, in the presence of an acid or basic catalyst. After reaction, the biodiesel and glycerin (co-product), impregnated of reaction excess and impurities, constitute two distinct phases that can separated by decantation or centrifugation process. The use of ethanol, instead of methanol, as transesterificant agent strains the phase separation process due to a major affinity of ethyl esters (biodiesel from ethanol) with the glycerin, what can provoke the necessity of centrifuge use in industrial process. In this project, was evaluated the separation process of immiscible phases that occur of a middle constituted of biodiesel, glycerin and ethanol, as representative of reaction middle that form after the transesterification reaction using ethanol as transesterificant agent through centrifugation and decantation process. It was studied samples with different ethanol content, at relative quantities to excess alcohol commonly used in the transesterification reaction. At decantation experiments were estimated the decantation time of glycerin phase of different samples. In this way was evaluated the ethanol excess influence. At centrifugation experiments, from a 24 factorial experimental design, was studied some technical operational parameters to obtain the better conditions to the centrifuge operation at phase separation process, at studied conditions. The studied parameters were: residence time, rotation velocity, temperature and ethanol mass in the sample. The better conditions of centrifuge operation were: 1000 rpm, 4 minutes of residence time and 25ºC or 3000rpm, 2 minutes of residence time and 25ºC.