San Antonio, Texas
June 10, 2012
June 10, 2012
June 13, 2012
Energy Conversion and Conservation
25.248.1 - 25.248.10
There is a strong need in the USA to decrease dependency on fossil fuels and implementsustainable energy policy. Many efforts are underway to power vehicles and equipment withalternative energy sources. One alternative fuel that has gained much popularity in the past fewyears is biodiesel. Biodiesel can be produced using virgin vegetable oil or waste vegetable oil(WVO) as the raw material. WVO is readily available and typically inexpensive; however theprocess to convert WVO into usable biodiesel is time consuming, requires a human operator torun the system, and necessitates a human perform a chemical titration for each batch produced.Due to these requirements, a typical biodiesel processor requires much user interaction which isnot eliminated by existing “automated” systems.In a two-semester sequence, two groups of senior design students engaged in the design,production, and testing of an automated biodiesel processor. The source of the WVO for thisproject is the university’s cafeteria and two other nearby locations. By converting this WVO tofuel for power generation, the overall waste generated from campus is reduced improvingenvironmental impact. The output of the process is certifiable biodiesel.The process to convert WVO into biodiesel first involves filtering solid contaminants from thecooking process out of the WVO liquid as well as residual moisture in the WVO is reduced. Atthis stage the WVO is ready for chemical conversion to biodiesel. WVO is basically atriglyceride. A lipid transesterification process is used to convert these triglycerides intomultiple fatty acid methyl esters (FAME). The process uses sodium hydroxide (lye) as a catalystand methanol (99%+ purity) as the primary reactant. Methanol is used because it is lessexpensive than other higher molecular weight alcohols (such as ethanol) and because the reactionis of higher quality. The major drawback of using methanol is that the resulting biodiesel has ahigher gelling temperature (cold filter plugging point) than that produced with ethanol. In thesoutheast, however, this is not a major issue. Glycerol is a byproduct generated from excess freefatty acids and is drained off after settling. The goal of the reaction, in essence, is thereplacement of the glycerin in the WVO with an alcohol group. After purification, glycerol isused in pharmaceuticals which may be an outlet for this byproduct.The processor designed and built by the students utilizes a programmable logic controller (PLC)in conjunction with pumps, valves, temperature sensors, etc., to completely handle theproduction of biodiesel with minimum user interaction. The system eliminates the need for thetitration process, circulates the fluid thorough the system, and presents the user with biodieselmeeting ASTM standards upon completion of a full cycle. This paper demonstrates the processused to automate biodiesel production and how the chemical titration procedure for each batch iseliminated.
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