INCREASING CORN THROUGHPUT IN DRY GRIND PROCESS FOR ETHANOL PROCESS

In a conventional dry grind process, corn is ground and mixed with water to produce slurry. The slurry is cooked; starch in the slurry is liquefied, simultaneously saccharified and fermented to produce ethanol. Typical solids during slurry preparation range from 30 to 34%. Higher solids result in higher ethanol concentration. High final ethanol concentration improves plant profitability by increasing plant capacity and improving plant efficiency. Corn solids higher than 34% are not used in dry grind corn process due to high mash viscosity (after cooking), increase in sugar concentration during fermentation (substrate yeast inhibition) and high final ethanol concentration (product yeast inhibition). Two new technologies have been developed which can be combined to reduce mash viscosity, maintain low sugar and ethanol concentration during fermentation and improve plant productivity. These technologies are: granular starch hydrolyzing enzymes and vacuum stripping of ethanol. Simultaneous liquefaction, saccharification, fermentation and distillation (SLSFD) can be conducted in one step with these two technologies and corn slurry solids higher than 34% can be used. In this study combination of granular starch hydrolyzing enzyme and vacuum stripping were evaluated for ethanol production with 40% slurry solids. Results were compared with conventional process using 40% slurry solids. The SLSFD process fermented slurry with negligible residual glucose content. In the conventional process residual sugar in beer started increasing at 20 hr and final residual sugar concentration of 5% (w/v) was observed. Amount of ethanol production and ethanol productivity of the SLSFD process was 20 to 40% higher compared to the conventional process

Nitrogen and Sulfur Concentrations and Flow Rates of Corn Wet‐Milling Streams

Nitrogen (N) and sulfur (S) concentrations can affect the market value of coproducts from corn wet‐milling. The composition of parent streams would be expected to affect composition of the resulting coproducts but there are few published data available to examine this relationship. Concentration and flow data are needed to determine which streams are important in modifying N and S coproduct concentrations. The objective was to measure concentrations and flows of N and S in corn wet‐milling streams. Samples were taken from 21 process streams from 3 wet‐milling plants during two periods of three weeks each; N and S concentrations of each sample were determined. There were large differences in N and S concentrations among processing streams; within most streams, N and S concentrations were similar among plants. Concentrations of N and S were related inversely to flow rates. Steepwater and gluten streams contained most of the N and S flow and provide an opportunity for modification. The process water stream carried large quantities of N and S and represents another opportunity for improving process efficiency and coproduct value.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141537/1/cche0260.pd

Effect of double density caging during Space Shuttle transport of laboratory rats

Male Sprague Dawley rats were housed in groups of four in polycarbonate cages at recommended density and thermal environmental conditions for 14 days prior to testing to ensure uniform acclimation to those conditions. Body weights averaged 286 +/- 7 g at the end of acclimation. Rat cages were assigned randomly to three treatments: (1) 4 rats/polycarbonate cage (877 sq cm, 20.3 cm high, 220 sq cm/rat), (2) 4 rats/mock AEM (MAEM) (620 sq cm, 155 sq cm/rat), and (3) 8 rats/MAEM (620 sq cm, 77.5 sq cm/rat). A comparison between the MAEM-DD and MAEM-SD treatments was done to determine if doubling rat density in AEM's stressed the rats. A comparison among MAEM treatments and the PC treatment was done to determine if any stress indications were due to the AEM. During this density challenge phase, all treatments were maintained at the same thermal environmental conditions (22.5 C and 50 percent RH) for 10 days. After the density challenge phase, half the rats from each group were sacrificed for body tissue and fluid analyses. The remaining half of the rats were housed at a density of 4 rats/cage in polycarbonate cages at normal thermal environmental conditions for an additional 10 days to determine if there were any differences in responses between treatments after a recovery period. The remaining rats were examined and sacrificed for body tissue and fluid analyses at the end of the recovery phase

Design and Evaluation of an Optimal Controller for Simultaneous Saccharification and Fermentation Process

Ethanol from corn is produced using dry grind corn process in which simultaneous saccharification and fermentation (SSF) is one of the most critical unit operations. In this work an optimal controller based on a previously validated SSF model was developed by formulating the SSF process as a Bolza problem and using gradient descent methods. Validation experiments were performed to evaluate the performance of optimal controller under different process disturbances that are likely to occur in practice. Use of optimal control algorithm for the SSF process resulted in lower peak glucose concentration, similar ethanol yields (13.38 +/- 0.36% v/v and 13.50 +/- 0.15% v/v for optimally controlled and baseline experiments, respectively). Optimal controller improved final ethanol concentrations as compared to process without optimal controller under conditions of temperature (13.35 +/- 1.28 and 12.52 +/- 1.19% v/v for optimal and no optimal control, respectively) and pH disturbances (12.65 +/- 0.74 and 11.86 +/- 0.49% v/v for optimal and no optimal control, respectively). Cost savings due to lower enzyme usage and reduced cooling requirement were estimated to be up to $1 million for a 151 million L/yr (40 million gal/yr) dry grind plant.Keywords: Cybernetic model, SSF process, Process disturbances, Saccharomyces cerevisiae, Optimal controller, Gradient descent, Dry grind corn ethano