Pilot-scale unit for biodiesel production: impact of UCO quality and properties on process yield

• Autor(a) principal: Gomes, Luís André Ribeiro Stahli
• Data de Publicação: 2018
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10400.13/2230
• topic: Biodiesel; Óleos alimentares usados; Transesterificação homogénea alcalina; Metanol; Metóxido de sódio; Used cooking oils; Homogeneous alkaline transesterification; Methanol; Sodium methoxide; Applied Biochemistry; .; Faculdade de Ciências Exatas e da Engenharia; Domínio/Área Científica::Engenharia e Tecnologia::Engenharia Química

Several alternative feedstocks have been tested for biodiesel production. As feedstock can represent up to 80% of the operation costs, used cooking oil (UCO) has been widely chosen. The UCO’s price is not the only advantage. Using waste as a raw material is also environmental friendly. In Madeira Island, there is only one pilot unit dedicated to biodiesel production, and it is located at the company Grupo Sousa / Metal Lobos Lda. in Industrial Free Zone of Madeira. This unit is designed to process two 1000L sets every three days through homogeneous alkaline transesterification in the batch regime, using methanol as a reactant, sodium methoxide as a catalyst, and UCO as feedstock. This raw material is collected in several commercial establishments such as hotels and restaurants. Its proper functionality could bring economic and environmental value to the company and Madeira Island by lowering exhaust emissions and fuel costs. The purpose of the present work is: (i) Test the pilot unit for possible operational failures and optimization possibilities, (ii) test the establishment of biodiesel production using UCO collected in the region, (iii) analyze how feedstock properties can influence transesterification yields Several laboratory tests (transesterifications) were performed to acquire a deeper understanding of the reaction behavior and variables before starting the pilot unit tests. On the pilot unit, four tests were performed using a minimum feedstock volume of 500L of UCO. Biodiesel production yields in the pilot unit varied from 78.52 to 90.37% (w/w). The lowest yields were the ones obtained using UCO with higher acidity values and lower alcohol to oil molar ratio in the reaction (biodiesel with purity of 96.3% (w/w) was obtained with UCO with 9.8% free fatty acids (w/w) and alcohol to oil molar ratio of 7:1). From the evaluation of the transesterification yields, it was possible to conclude that in this pilot unit the influence of the feedstock’s acidity is not so significant, but, it is of utmost importance to further analyze the impact of the impurities on the glycerol quality, as this may determine the economic viability of the whole process. It was concluded that the pilot unit was functional for biodiesel production, but, due to the feedstock properties variability, optimization should be taken into consideration. Improving both process and procedures such as UCO collection and storage could raise the unit’s yield.