Effects of compositional variables on fouling behavior of thin stillage

The presence of fouling in evaporators can increase energy consumption as well as capital and labor costs. During corn ethanol production, fouling occurs when thin stillage is concentrated in multiple effect evaporators to form condensed distillers solubles. Limited studies have been conducted on fouling of corn ethanol processing. Process streams are biological in origin and have variable compositions. The objective of this study was to develop an improved understanding of components that accelerate fouling of thin stillage evaporators. An annular fouling probe was used to evaluate compositional variables on fouling behavior of dry grind corn thin stillage. Three experiments were performed with commercial processing streams. In the first experiment, the effects of carbohydrate materials in thin stillage on evaporator fouling were investigated by adding starch and sucrose. In the second experiment, commercial thin stillage samples were treated by adding wet cake. The third experiment was designed to observe if the age of thin stillage sample would affect fouling. The results indicate that fouling resistances increased with starch addition, as well as with wet cake addition, at equal total solids contents. Insoluble starch addition had larger effects than soluble sucrose addition. Sucrose alone did not cause increased rapid fouling.