Design of a pilot plant for biodiesel production from high free fatty acid oils

Abstract

Biodiesel or fatty acid methyl ester is a fuel that can be produced from lipid sources. It is popular as a totally renewable, nontoxic and biodegradable alternative fuel for fossil based diesel due to its numerous environment benefits associated with its use. Currently, biodiesel is produced mainly using edible oils and the rest is covered by non-edible oils, animal fats and waste cooking oils (WCOs). The lab-scale studies of the research identified that, locally available feedstock materials such as Coconut, Palm, Rubber seed oil (RSO), Jatropha, Neem, Lard and WCO can be successfully used in biodiesel production. The study used alkali-catalyzed transesterification process to produce biodiesel and proven the feasibility of using it for oils with FFA content less than 2.0%. The oils with FFA content greater than 2.0% were pre-treated using acid-esterification. The optimization of oil pre-treatment conducted in lab-scale using RSO showed that 0.05 g of H2SO4/g of FFA, 3.0 g of methanol/g of FFA and 30 min reaction time are the optimum process conditions, and 2.0 or 2.5 g of methanol/g of FFA with 0.075 or 0.100 g of H2SO4/g was recommended for commercial-scales. The study identified that the FFAs remained after pre-treatment further reduced with settling time and invented that single acid esterification step followed by extended settling can be used as a novel FFA reduction method. Study also introduced a simplified chemical dosage estimation method based on FFA content of the oil. A 50 litre portable reactor system was designed and fabricated with multi disciplinary units based on lab-scale results for pilot-scale studies. The designed unit is capable of carrying out complete biodiesel production process from pre-treatment to drying under both manual and automatic modes. The studies also proved the potential of using the pilot-unit in biodiesel production using alkali-catalyzed transesterification.