A Pilot Plant to Produce Biodiesel from High Free Fatty Acid Feedstocks

Biodiesel is an alternative diesel fuel consisting of the alkyl monoesters of fatty acids from vegetable oils or animal fats. Currently, most biodiesel is made from soybean oil, methanol, and an alkaline catalyst. However, there are large amounts of fats and oils that are unsuitable for human consumption that could be converted to biodiesel at lower cost. The problem with processing these waste oils is that they often contain large amounts of free fatty acids that cannot be converted to biodiesel using an alkaline catalyst. These free fatty acids react with the alkaline catalyst to produce soaps that inhibit the separation of the biodiesel, glycerin, and wash water. Previous research has developed a process for pretreating these high free fatty acid feedstocks using acid catalysts which do not form soaps. The objective of this study was to construct a pilot plant to produce biodiesel from a wide variety of feedstocks including those with high free fatty acids. A 190-liter batch pilot plant has been built which can process high free fatty acid feedstocks using an acid-catalyzed pretreatment followed by an alkaline-catalyzed transesterification. Case studies of pilot plant-scale production of biodiesel from soybean oil, yellow grease with 9% free fatty acids, and brown grease with 40% free fatty acids are presented. The effect of varying the reaction parameters is discussed and the separation and washing processes are described. Estimates of the fuel cost using different feedstocks are also provided.

[1]  R. Feuge,et al.  Modification of Vegetable oils. IV. Reesterification of fatty acids with glycerol , 1945 .

[2]  A. E. Bailey,et al.  Modification of vegetable oils , 1946 .

[3]  D J Hassett,et al.  SUNFLOWER OIL METHYL ESTER AS A DIESEL FUEL , 1982 .

[4]  S. Romano.  Vegetable oils: a new alternative , 1982 .

[5]  J. Fuls,et al.  Comparative combustion studies on various plant oil esters and the long term effects of an ethyl ester on a compression ignition engine , 1982 .

[6]  F. J. C. Hugo,et al.  TRACTOR ENGINE PERFORMANCE ON SUNFLOWER OIL FUEL , 1984 .

[7]  E. H. Pryde,et al.  Variables affecting the yields of fatty esters from transesterified vegetable oils , 1984 .

[8]  Peter Tritthart,et al.  Diesel fuel derived from vegetable oils, III. Emission tests using methyl esters of used frying oil , 1988 .

[9]  H. Aksoy,et al.  Evaluation of Turkish sulphur olive oil as an alternative diesel fuel , 1988 .

[10]  C. L. Peterson,et al.  A batch type transesterification process for winter rape oil. , 1989 .

[11]  Ke-Shun Liu.  Preparation of fatty acid methyl esters for gas-chromatographic analysis of lipids in biological materials , 1994 .

[12]  S. J. Marley,et al.  Fuel properties and emissions of soybean oil esters as diesel fuel , 1996 .

[13]  Jon H. Van Gerpen,et al.  The Effect of Biodiesel Fuel Composition on Diesel Combustion and Emissions , 1996 .

[14]  Yu Zhang,et al.  Combustion Analysis of Esters of Soybean Oil in a Diesel Engine , 1996 .

[15]  Jon H. Van Gerpen,et al.  Fuel Properties and Engine Performance for Biodiesel Prepared from Modified Feedstocks , 1997 .

[16]  Jon H. Van Gerpen,et al.  Determining the Influence of Contaminants on Biodiesel Properties , 1997 .

[17]  Robert L. McCormick,et al.  Combustion of fat and vegetable oil derived fuels in diesel engines , 1998 .

[18]  J. V. Gerpen,et al.  BIODIESEL PRODUCTION VIA ACID CATALYSIS , 1999 .

[19]  Mustafa Canakci,et al.  Production of biodiesel from feedstocks with high free fatty acids and its effect on diesel engine performance and emissions , 2001 .