Biofuels are present in the global scenario as an energy source derived from organic biomass, representing an economic and environmental alternative. They are a renewable source of energy with low rates of pollutants emissions and, consequently, less carbon dioxide is released into the atmosphere. The obtaining of bioethanol is originated from a fermentation process, in which a multi-component mix is generated and the anhydrous bioethanol is separated. To obtain such compounds, some operations are required, such as extractive distillation, where solvents are added in order to "break" the ethanol-water azeotrope. In the present work two solvents were used: Glycerol and the ionic liquid [BMIM][BF4]. Starting from a multi-component mixture composed by ethanol, water, acetic acid and isoamyl alcohol, the bioethanol purification process was simulated using the computational tool Aspen Plus® simulator. Through a comparative analysis, it was possible to determine which solvent presented the best performance, where operational parameters such as the reflux ratio, distillate rate and the solvent flow were analyzed. The purity degree of 99.7% in mass and an approximate production of 2764 kg/h of anhydrous bioethanol were fixed and the results showed that glycerol was the solvent that presented greater economic and environmental viability for the process, considering the operational parameters mentioned above.
Contagem deárvores geradoras de um grafo completo Counting of spanning trees of a complete graph Resumo Em 1889, Arthur Cayley publicou um artigo com uma fórmula para a contagem deárvores geradoras (spanning) de um grafo completo. Esse teorema diz que: Sejam n ∈ N e Kn o grafo completo com n vértices. Então o número deárvores geradoras de Kné dado por n n−2. O presente trabalho constitui-se de uma breve revisão da literatura sobre os conceitos e resultados básicos da teoria de grafos e uma demonstração detalhada da Fórmula de Cayley, dada pela construção minuciosa de uma bijeção entre o conjunto deárvores geradoras e um conjunto especial de sequências numéricas. Por fim, trazemos um algoritmo, que descreve uma forma precisa para a construção dasárvores geradoras obtidas de Kn a partir de sequências de Cayley-Prüfer.
Os biocombustíveis apresentam-se no cenário global como uma fonte alternativa de energia para os combustíveis fósseis, se destacando pelo caráter renovável e baixos índices de emissão de partículas poluentes ao ambiente. A produção de bioetanol é proveniente do processo de fermentação, no qual é gerada
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