Effect of corn oil on thin stillage evaporators

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 st illage 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 perio dically taken down for maintenance and cleaning. Fouling caused by thin sti llage containing different amounts of oil was studied using an annular foul ing probe. It was determined that the rate of fouling in a dry-grind ethano l plant is three times higher when compared with that in a wet-milling etha nol plant. The addition of oil to wet-milled thin stillage significantly af fected the rate of fouling. Fouling resistance increased with an increase i n 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 co ncentration of oil increased in dry-grind ethanol thin stillage, the rate o f fouling decreased. These results suggest that the Quick Germ process will reduce the rate of heat transfer equipment fouling in a dry-grind ethanol plant, which will decease capital costs and maintenance costs.