(587al) Fouling Rates of Model Carbohydrate Solutions and Their Interaction Effects

Thin stillage fouling is caused by the deposition of proteins, fat, fiber and carbohydrates on evaporator surfaces during corn ethanol production by dry grind process.  Heat transfer equipment fouling results in losses from increased capital costs, antifoulant chemicals and decreased product output.  Early work on starch-sucrose interactions showed that an increase in starch content has higher impact whereas sucrose alone did not have any effect.  Residual sugars from fermentable and unfermentable starch components in thin stillage may cause evaporator fouling.   The objective of this study is to obtain fouling curves for carbohydrate solutions with varying dextrose equivalent (DE) and also the interaction effects of DE sugars with total solids content on evaporator fouling. 

A portable fouling unit was built to obtain fouling trends of model solutions for a constant bulk temperature.  Accelerated fouling concept was adopted for all fouling experiments as fouling is a slow process and it may takes days or even months to completely foul the test section. Samples obtained from Grain Processing Corporation (GPC^TM) include MALTRIN® M180, M200, M440, M500, corn syrup solids and crude corn oil.  All the samples are pharmaceutical grade and stored in cool and dry area.  Dissolution rates and carbohydrate profiles will be taken into consideration to explain the fouling trends.  Model solutions are assumed to exhibit Newtonian fluid behavior and their viscosities will be measured using a Rapid Visco Analyzer to determine the Reynolds Number (N_Re).  Solutions zeta potential will be measured and compared to the fouling tendencies against total solids content.    In addition to carbohydrate fouling study, a study on the interaction effects of carbohydrates with crude corn oil and protein will also be conducted.