Modelagem e simulação de equipamentos flash reativos para a produção de biodiesel

Abstract

In search for more sustainable alternatives to gradually replace fossil fuel in the world’s energetic mix, biodiesel is currently seen as a great option. Biodiesel is considered a renewable source as it can be produced from vegetable (oleaginous) or animal sources it emits less pollutants from its combustion and its performance as a fuel is comparable with common diesel’s. Moreover, its production has positive impacts on the local economy. The reaction responsible for its production is called transesterification and researches on the field aim on proposing processes and operating conditions that allow a better yield as well as a reduction of the costs on the separation of the main product. Recent studies emphasize the efficiency of reactive distillation processes, which combines separative processes based on the volatility difference of its constituents and the chemical reaction. It allows the products to be simultaneously formed and separated from the reactants and/or subproducts, guaranteeing a better global energetic efficiency especially due to the displacement of the reaction’s equilibrium. An example of this kind of unit operations is the reactive flash, which is a system regulated by the thermodynamic equilibrium between its phases and the chemical kinetics of the reaction in liquid phase. The present work investigates addresses the modelling and simulation of the reactive flash as well as the analysis of the effects from the variation of heat rate supplied, pressure, proportion between reactants fed and current distribution between two flash in series. Experimental, thermodynamic and kinetic data were obtained from the literature and from ProSim® simulator. The differential-algebraic system of equations that represent the process was solved with the predictor-corrector Gear’s method through Fortran language. The results obtained have legitimized the developed model once they were compared with those available on the literature. In addition, they have shown that conversion is directly proportional to pressure and alcohol percentage in reactants, while it has two optimal zones for heat rate supplied. Lastly, the two flash in series configuration have shown better efficiency with a bypass on the feed stream.