Identificador: TDX:1637
Autores: Avellaneda Vargas, Fredy Augusto
Resumen:
The high petroleum dependence of the world, the instability of the international petroleum market and the petroleum price fluctuations, besides its social and environmental impact, have directed the world to the search of alternatives sources of energy, like biofuels. Biodiesel or FAME (Fatty Acid Methyl Ester) is a renewable biofuel, environmentally friendly, produced from vegetable oils or animal fats, that can be used totally or partially to replace diesel without requiring any modification in the engines. The present research try to solve the high difficulty in producing biodiesel from crude palm oil, due to the high acid index, and the amount of gums and impurities presents in the crude oil. In this sense, an experimental study is presented with the objective of compare and optimise the biodiesel production at laboratory scale by transesterification reaction with methanol using NaOH as catalyst. The experiments were carried out varying the molar ratio methanol:oil, and the amount of catalyst used, as well as different oil pretreatment (using crude oil without pretreatment, degummed with phosphoric acid or preesterified with acid catalyst like sulphuric acid). The parameters that were measured and used for comparison were the yield of biodiesel (in grams of biodiesel produced per gram of crude palm oil) and its FAME % according to standard norm UNE 14103. The best biodiesel produced was analysed according to the standard European norm UNE 14214 in order to evaluate its global quality. The acid preesterification process at the optimal conditions found, transforms the crude palm oil in a suitable raw material for transesterification reaction, by a simple and rapid process, reducing significantly the losses due to refining, favouring the yield and producing a biodiesel with a very good quality. On the other side, a preesterified palm oil and a recycled oil with a low free fatty acid concentration, were used to compare conventional transesterification in batch mode with continuous transesterification in continuous mode, using a new tubular reactor never used before. This tubular reactor allows the reactives (oil, methanol and sodium hydroxide) to flow through a tube having helicoidal form, submerged in a heating water bath at 60º. This reactor has 5 sampling points, not uniformly distributed, allowing to take samples at 5 different reaction times. The helicoidal distribution allows to eliminate the mechanical stirring and decrease the reaction time needed to complete transesterification. With the purpose of improve the quality of the biodiesel produced, different variations to the helicoidal system were incorporated, such as the use of a static micro-mixer, and the use of ultrasonication in the water bath to supply energy. The helicoidal reactor used in this thesis, uses the synergy produced by the effect of the microdiscontinuities originated by the pump pulses, and the constant change of direction of the flow forces during the helicoidal trajectory to which the fluid is forced to pass through. This increases the mixing effect to the immiscible phases, optimising the intimate contact between the reactants, which reduced significantly the time necessary for the transesterification, and in the case of the preesterified oil, allowed producing a biodiesel with a purity higher than the minimum limit imposed by the European norm UNE 14214.
Repositori URV