Techno-Economic Modeling of Coproduct Processing in a Corn Based Ethanol Plant in 2012
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Coproducts, such as Distillers Dried Grains with Solubles (DDGS), produced during ethanol production are essential to the economic sustainability of each ethanol plant as they provide an additional source of revenue. DDGS is extensively used as animal feed, but has a relatively low market value compared to the biofuel. By fractioning DDGS into lighter and heavier fractions, the overall composition changes potentially increasing the value of the coproducts as they become more desirable to different markets. Earlier studies have examined fractionating DDGS using sieves and aspirators. This project examined the techno-economics of adding fractionation systems onto an existing 40 million gal/y ethanol plant. The model allowed for estimations of fixed capital costs, annual operating costs, annual revenues, and net profits, in order to determine the economic feasibility of adding three different fractionation systems. The first fractionation system consisted of a single sieve, and the retained material was passed through an aspirator. The second system was similar to the first but with a second sieve and aspirator. The third system added a third set of them. In addition to utilizing different fractionation systems, the scenarios examined the effects extracting corn oil and producing DWG in addition to DDGS. The fractionation systems examined in this study increased the capital costs associated with the facility, but did not greatly affect the overall annual operating costs. The net profits in the four most profitable scenarios were $0.349/gal EtOH/y (scenario 14), $0.350/gal EtOH/y (scenarios 6 and 10), and $0.351/gal EtOH/y (scenario 2).