Michael Hora
Principal Engineer
Distillers Corn Oil (DCO) has become one of the most valuable byproducts in ethanol production, offering significant revenue potential as the highest-value component from a product price point. Most of the corn oil resides in the germ (80-90%), but additional oil is embedded in the outer layer and corn fiber. Extracting this bound oil efficiently can make a substantial difference in profitability. Optimizing oil extraction requires a deep understanding of the science and engineering involved. There are pitfalls and pathways to maximizing DCO yield and profitability.
Understanding Oil Separation Mechanics
Oil separation can be achieved through mechanical or chemical means. One chemical method is using surfactants to break emulsions of DCO with other fluids, encouraging oil to form larger droplets, which improves separation. More surfactant exposure time enhances this effect, leading to greater oil recovery. Mechanical solutions include utilizing a combination of time, centrifugal force, and temperature to achieve the needed droplet size and thus improved separation.
Oil is a sensitive molecule. Excessive mechanical agitation, such as running it through a centrifugal pump, can break apart oil globules and hinder separation. Progressive cavity pumps are ideal as they preserve the integrity of oil droplets, ensuring better recovery.
Knowing how to build out a mechanical oil release process to achieve maximum oil separation is not the area of expertise for most plant teams. Thus, a chemical solution is often chosen as an alternative even though most mechanical solutions are less expensive and more consistent over the long run as compared to chemistry.
Additional consideration needs to be given to where in the process oil is released and under what situations it can become bound and inseparable from the fiber and germ matrix. FQT has developed multiple oil separation technologies, each one designed to separate free and bound oil throughout the ethanol production process.
Releasing Bound Oil: The Role of Selective Grind Technology
One major challenge in oil extraction is freeing oil that remains bound to corn fiber and germ. If oil remains within fiber, it exits with wet cake, representing a lost opportunity. The goal is to direct as much free oil as possible into the thin stillage stream.
Fluid Quip Technologies’ Selective Grind Technology (SGT™) plays a vital role in the front end of the ethanol production process in releasing oil. Traditional dry grinding merely breaks corn kernels into chunks, while SGT further reduces particle size, especially targeting germ chunks. Breaking apart these germ chunks releases more oil, leading to a 10-20% uplift in oil yield. The key advantage of SGT is that it shears germ particles without creating excessive fine fiber, which could otherwise cause fouling in the plant.
SGT utilizes patented disc mills that shear and rip apart germ particles effectively. This innovative grinding process enhances oil release without increasing fine insoluble solids that can otherwise hinder separation.
Fermentation Time: Hidden Lever for Oil Yield
Fermentation itself contributes to oil extraction. Ethanol acts as a natural solvent, pulling oil into solution. Higher ethanol concentrations and longer fermentation times can therefore improve oil yield. Releasing oil early in slurry and liquefaction allow additional oil to be released during fermentation as the ethanol can act as a “deep bed extractor” and pull more oil from the germ particles if they are sheared open. There is a linear relationship between fermentation time and oil yield, but exceeding optimal thresholds can have the opposite effect.
The Importance of Fiber Washing and the Role of FQT’s DCO Technology™
Effective oil separation depends on maintaining a clean syrup stream. “Clean” in this context means minimizing insoluble solids. Cleaner syrup allows for easier oil separation and minimizes fouling in evaporators. Additionally washing the oil away from the fiber stream post distillation (whole stillage), as part of this clean up, allows for the separation of additional oil upwards of 20-30% more.
By minimizing unfermentable solids the backset stream, fermentation efficiency/capacity is gained. By cutting unfermentable solids in half, plants can replace the lost volume with fermentable starch, increasing throughput and overall oil yield.
FQT’s DCO Tech involves two stages of stillage fiber washing, directing solubles and oil into thin stillage. The thin stillage is then sent to a clarifier—a high G-force centrifuge which produces a clean centrate with high oil content and minimal solids.
By effectively separating solubles from insoluble solids, the DCO system prevents unfermentable solids from cycling back into the front-end process. This cleaner backset stream allows plants to grind more corn, push higher titers, and increase net oil output.
The Importance of Syrup Conditioning and the Role of FQT’s Overdrive™
Syrup conditioning plays a vital role in maximizing both oil yield and overall operational efficiency in ethanol production. Retention temperature and time must be carefully balanced—too much heat or excessively long retention can negatively impact oil recovery. The right “heat and hold” approach optimizes conditions to maximize free oil recovery.
After releasing as much oil as possible through mechanical separation, it is key to ensure optimal syrup conditions to achieve effective oil recovery from the syrup. Conditioning the syrup prior to being fed through the oil recovery centrifuge achieves optimal conditions for oil recovery in the centrifuge. The Overdrive technology from FQT ensures that the syrup is held at the optimal temperature for the optimal time to appropriately condition the syrup. Further, where other heat and hold systems have failed with fouling and CIP issues; the proprietary design and automation of the Overdrive system allows it to be a ‘set it and forget it’ component of an oil recovery system.
A Modular Approach to Capital Investment
One of the major advantages of modern oil extraction technologies is their modularity. Each system, from SGT to DCO Tech, to Overdrive, functions like a “building block,” adding to previous investments without cannibalizing other processes. At Fluid Quip Technologies, efficiency in capital allocation is a priority. By ensuring that all technologies are bolt-on, plants can maximize output without stranding capital.
The Pathway to Profit
So, what are the pathways to profitable ethanol production? Optimizing DCO yield requires a multi-faceted approach. From advanced grinding, fermentation optimization, modular separation technologies, and syrup conditioning, every step plays a crucial role. By implementing the right combination of these strategies, ethanol plants can unlock significant revenue potential while maintaining process efficiency.
In the ever-evolving ethanol industry, staying ahead requires not just adopting new technologies but understanding the science behind them. Those who master these techniques will achieve the highest returns from their distiller’s corn oil operations. Talk with an expert from Fluid Quip Technologies to find the right mix for your operation.