Modelagem e simulação de uma planta de destilação reativa para a produção de biodiesel

Abstract

In this work, the reactive distillation process for biodiesel production using castor oil and soybean oil as feedstocks is presented.Process simulations using the commercial simulator Aspen plus ® in conjunction with factorial design techniques were used for finding the process operating conditions that will produce the largest amount of biodiesel.For the simulations, firstly, the characterization of vegetable oils and biodiesels by means of representative compounds was performed into the simulator. It was necessary, for a successfull characterization, to carry out experimental measurements of some properties of these compounds. The simulations were performed using the NRTL thermodynamic model. The interaction parameters missing in the simulator data base were estimated by UNIFAC method. The kinetic model employed in castor oil study was published by de Lima da Silva. Because kinetic data for soybean oil transesterification with ethanol are not reported in the open literature, these parameters were determined and used in the simulations.In the study of the castor oil biodiesel production system, initially a 2 4 factorial design was done in order to analyze the effect of the variables: feed flow rate of oil (vo), molar ratio alcohol: oil (rm), reflux ratio (rf) and molar ratio between the distillate / feed based on ethanol (d: f) in the process yield and simultaneously to obtain a model that adequately represents the behavior of the system. Following this, it was used the method of the path of steepest ascent to determine quickly and simply the region that will maximize the production of biodiesel. Finally, based on results obtained in the previous section, it was developed a new factorial design 2 4 to find the best combination of variables, which would provide the largest biodiesel production. Sensitivity studies were performed to support the factorial design results. In the study of the system involving soybean oil, was followed the vii same methodology described for the castor oil, with the difference that the factorial designs were all 2 3 . The results obtained with the twou oils show that it is possible to obtain high yields in the process using a low molar ratio ethanol: oil and a more compact plant.Additionally, it was introduced in the simulations, stage efficiency values and component efficiency values calculated using the Barros & Wolf equation. It was concluded that efficiency has no effect on the performance of the reactive distillation process for biodiesel production.Finally, it was performed a simulation of a reactive packed distillation column for biodiesel production. The operating conditions of the simulation were taken from an experimental study conducted by the research group in biodiesel lab LDPS, which is reported in this dissertation.