multi-step integrated technology, supercritical fluid extraction of soybean oil, oil transesterification with methanol/ethanol, biodiesel fuels
A multi-step integrated technology to produce high quality vegetable oils and biodiesel fuels is proposed, documented for technical and economic feasibility, and preliminarily designed. The first step of the integrated system consists of soybean oil extraction with supercritical fluids. The second step is designated to transform the soybean oil into biodiesel through transesterification with supercritical methanol or ethanol. The degradation of glycerol to light fuel components renders this method very simple by eliminating the costly steps of glycerol separation. Part of the biodiesel is directly consumed by a diesel engine integrated in the system which, in turn, provides the mechanical power needed to pressurize the system as well as the heat of the exhaust gases, heat required for the extraction and transesterification steps. Different versions of this system can be implemented based on the main target of the technology: oil and biodiesel production or diesel engine applications. Various process options considered for biodiesel fuel production estimate break even costs of biodiesel less than $ 2.56 per gallon with the diesel generator for a plant of 15000 gallon/day or less tan $ 2.49 per gallon for a plant of 9200 gal/day with a burner replacing diesel generator. Also, the efficiency of the diesel engine combustion and cleaner emissions render the proposed technology very attractive for the transportation sector when only the transesterification step is carried out just to provide superior fuels to diesel engines with minor engine retrofitting.