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Effect of Corn Oil on Thin Stillage Evaporators

¹Assistant professor and professor, respectively, Department of Agricultural Engineering, University of Illinois, Urbana, IL 61801. Mention of product or trade names does not imply endorsement by the University of Illinois. ²Corresponding author. E-mail: vsingh@uiuc.edu ³Chemical Engineer, Industrial Technology Development Center Building 900, Argonne National Laboratory, Argonne, IL 60439.

Removal of the germ at the front end of the dry-grind ethanol process using the Quick Germ process reduces the amount of oil in thin stillage. Thin stillage with 4–6% solids is dewatered to 25–30% solids by evaporation. Thin stillage evaporators in a dry-grind ethanol plant foul and have to be periodically taken down for maintenance and cleaning. Fouling caused by thin stillage containing different amounts of oil was studied using an annular fouling probe. It was determined that the rate of fouling in a drygrind ethanol plant is three times higher when compared with that in a wet-milling ethanol plant. The addition of oil to wet-milled thin stillage significantly affected the rate of fouling. Fouling resistance increased with an increase in oil concentration for wet-milled thin stillage up to a concentration of 1.41%. At a concentration of 1.47%, the rate of fouling decreased. As the concentration of oil increased in dry-grind ethanol thin stillage, the rate of fouling decreased. These results suggest that the Quick Germ process will reduce the rate of heat transfer equipment fouling in a drygrind ethanol plant, which will decease capital costs and maintenance costs.