A A C C   2 0 0 0   A n n u a l   M e e t i n g

The fouling rate of thin stillage from dry grind ethanol process using quick germ process was investigated using an annular fouling probe and a data collection system. The probe contained a variably heated surface adjusted to simulate the surface temperature of an evaporator. The heated region caused certain constituents of the thin stillage to adhere to the heated surface, thus fouling the probe over time. The insulating effect of fouling caused the temperature to increase inside the probe. Processing methods has been shown to affect surface fouling characteristics. Previous work with steepwater showed a 80% decrease in rate of surface fouling caused by a process change. The thin stillage from the quick germ process were prepared by first separating the germ from the corn. The degermed corn was then cooked, saccharified and fermented to produce ethanol. This quick germ process involved soaking the corn in water for 12 h at 59°C, milling the soaked corn and separating the germ. The thin stillage obtained from the ethanol production was used for the study. The fouling rate of the sample was determined at an initial evaporator surface temperature of 99°C. A 30-L batch of each sample was circulated through the fouling probe at a flow rate of approximately 13 liters per minute until the inner surface temperature of the probe reached 200°C. The bulk fluid temperature was main tained at approximately 40°C. A similar experiment was done on thin stillage processed without germ removal. The results showed a decrease in fouling resistance and rate of fouling for the thin stillage samples from the quick germ process.