Optimization and modeling of flow characteristics of low-oil DDGS using regression techniques

Authors: BHADRA, RUMELA - Kansas State University; AMBROSE, KINGSLY R. - Purdue University; Casada, Mark; SIMSEK, SENAY - North Dakota State University; SILIVERU, KALIRAMESH - Kansas State University

Submitted to: Transactions of the ASABE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/15/2016
Publication Date: 1/1/2017
Citation: Bhadra, R., Ambrose, K.P., Casada, M.E., Simsek, S., Siliveru, K. 2017. Optimization and modeling of flow characteristics of low-oil DDGS using regression techniques. Transactions of the ASABE. 60(1):249-258. doi:10.13031/trans.11928.

Interpretive Summary: Distillers dried grains with solubles (DDGS), with its substantial protein content (approximately 30% dry basis, d.b.) and fat content (8% to 12% d.b.), is a widely used animal feed in the U.S. cattle and swine industries. DDGS often experiences flow problems when emptying railcars, leading to railcar damage and disruption of the transportation system. Recently over half of the dry grind ethanol plants in the U.S. have begun extracting approximately half of the corn oil (fat source) from the DDGS to provide additional income from sale of the extracted oil to the biodiesel industry. This study was conducted to understand the flow properties of this new low-oil DDGS and correlate them with storage and processing conditions. Conditions studied were temperature (20°C,40°C,60°C), relative humidity (RH) (40%,60%,80%), moisture content (MC) (9%,11%,14% d.b.), consolidation pressure (CP) (generated by 0, 10, and 20 kg overbearing loads), and consolidation time (CT) (2, 4, 6, 8 days). Results showed MC, temperature, and RH were the most influential variables on flow properties and yielded regression models to predict and quantify flow behavior with varying storage conditions. These results are an important resource for low-oil DDGS producers and handlers, providing models to predict and avoid conditions that lead to flow problems.

Technical Abstract: Storage conditions such as temperature, relative humidity (RH), consolidation pressure (CP), and time affect flow behavior of bulk solids like distillers dried grains with solubles (DDGS), which is widely used as animal feed by the U.S. cattle and swine industries. The typical dry grind DDGS production process in most corn ethanol plants has been adapted to facilitate oil extraction from DDGS for increased profits, resulting in production of low-oil DDGS. Many studies have shown that regular DDGS cakes and flow is an issue during handling and transportation. This study measured the dynamic flow properties of low-oil DDGS. Flow properties such as stability index (SI), basic flow energy (BFE), flow rate index (FRI), cohesion, Jenike flow index, and wall friction angle were measured at varying temperature (20°C, 40°C, 60°C), RH (40%, 60%, 80%), moisture content (MC) (8%, 10%, 12% wb), CP (generated by 0, 10, and 20 kg overbearing loads), and consolidation time (CT) (2, 4, 6, 8 days) for low-oil DDGS. Response surface modeling (RSM) and multivariate analysis showed that MC, temperature, and RH were the most influential variables on flow properties. The dynamic flow properties as influenced by environmental conditions were modeled using the RSM technique. Partial least squares regression yielded models with R2 greater than 0.80 for SI, BFE, and cohesion as a function of MC, temperature, RH, CP, and CT using two principal components. These results provide critical information for quantifying and predicting flow behavior of low-oil DDGS during commercial handling and transportation.