Boosting the Back End's Bottom Line

A new technology targeting whole stillage produces enchanced coproducts and new possibilities.
By Kris Bevill | September 23, 2010
With concerns about the distillers grains market reaching saturation, tight margins, and the possibility of increasing energy costs, a new technology is being tested at the plant level to produce enhanced and new coproducts. Fluid-Quip Inc. is a Springfield, Ohio-based equipment manufacturing firm that has been engineering and manufacturing wet-mill separation equipment for more than 20 years. The company recently developed a a new filtration centrifuge and system to recover coproducts from whole stillage at dry grind plants, called the Maximized Stillage Co-products system. "This patent-pending process is focused on recovering protein from whole stillage," says Michael Franko, technical projects manager at Fluid-Quip Inc.

Whole stillage is sent to a filtration centrifuge, where the distillers grains are washed to remove the proteins, solubles and oil away from the fiber material. The fiber is sent through dryers just as traditional distillers grains would be, while the corn oil and protein are sent through a second centrifuge. There, the oil and solubles are washed away from the protein, creating a cleaner stream for evaporation which allows for improved corn oil recovery, as well as a high-protein coproduct that Fluid-Quip has named StillPro. Franko says the result is a win-win for ethanol producers. "You get the protein without affecting ethanol yield," he adds.

The fiber coproduct created in Fluid-Quip's process has a few distinct differences compared to traditional distillers dried grains (DDG). "We've basically taken the DDGs, lowered the protein and lowered the oil slightly," Franko says. "So, they take a slight discount on it, but the nice part is that the plant is able to sell it through their traditional DDGS channels." Frankos says some of the producers he has introduced the system to have been more excited about the fiber product's potential for co-generation use or cellulosic ethanol conversion than marketing it as a feed product. Corn oil produced through the MSC system can be marketed for biodiesel production, which is a typical use for that coproduct.

The protein product, which Franko compares to soybean meal or corn gluten meal, has diverse application possibilities. "We have a mix that's part protein and part yeast, so it's a unique type of protein, which is why the amino acid profile is somewhat unique," he explains. The content of the product makes it a good possibility for feeding poultry, swine and possibly fish and can demand a higher selling price, similar to meal produced at wet mills. "The plant we're working with is doing a great job of developing those markets and conducting feed studies," Franko says. "They've conducted some initial poultry market studies [and] they're moving into some other areas working with major nutritionists, because we want to make sure that everyone's very comfortable with the products."

Field Test
The 52 MMgy ethanol plant conducting tests on MSC system's coproducts, which declined to be named for this article, began operating Fluid-Quip's system a year ago. It recently commissioned a second filtration centrifuge, which increased yield and allowed for greater throughput. A third centrifuge will be installed this fall, which will allow for full operation of protein production, according to Franko. He says a 50 MMgy plant could temporarily get by with only two centrifuges, but a third is strongly recommended and is automatically included in the base equipment package. Franko recommends four centrifuges for a 100 MMgy plant.

Capital equipment costs for a 50 MMgy base package, which includes three centrifuges and a dryer, is less than $7 million, says Franko. Installation and construction costs will vary depending on the situation. The module is designed to be a stand-alone building, which can be constructed next to an energy center at a typical ethanol plant. Construction and commissioning of the system can be completed within one year and, depending on construction and installation costs, producers can expect to achieve a return on their investment in only two years. "The dependency there is on installation and engineeringhow the plant is set up and where we can do the tie-ins," Franko adds. Fluid-Quip estimates that a 52,000 bushel-per-day dry mill can generate $10 million in annual revenue through products created in its MSC system while discounting DDGs.

No Interruptions
One of the complaints producers have with front-end fractionation is the length of installation time and disruption of ethanol production. Franko says Fluid-Quip's system does away with both of those concerns. "The idea is that we do not interfere with the production of ethanol on the front-end at all," he says. "That's their main business, that's what they do best, so we don't want to disturb that. We want to take the whole stillage from the distiller bottoms after they're done and improve their fractionation on the back-end side of things. The nicest part is, for tying into the plant operation, our engineers have designed it so that tying in and plant interruption really should be minimal. We are able to tie-in with scheduled shutdowns so that there are no interruptions other than possibly one day to start up the process."

Because the system is relatively easy to start up, it's also easy to shut down. "If, for some reason, we want to shut down, we want to go back to making DDGS, you can take it offline very quickly," Franko says. The plant that is currently using the MSC system has tested shutting down the equipment and was able to do so in a one hour.

The MSC system requires no additional natural gas usage and demands only slightly more electricity use, which Franko says has not been a drawback for any of the plants where he's introduced the equipment. No additional water is required to operate the system because wash water used in the centrifuges can be taken from various sources within the plant. The system has also shown potential benefits in the maintenance requirements for a plant's evaporation system. "Many plants are running their DDG dryers and evaporators to the limit," Franko says. The plant currently operating the system discovered during a scheduled shut down for cleaning that the evaporation system required minimal cleaning. Franko attributes that to the system's process of removing protein from the evaporation stream.

Overall, Franko believes that forward thinking members of the ethanol industry realize a back-end fractionation system offers them an opportunity to increase bottom line revenues at a fraction of the cost of front-end systems. "What I hear from plants is the significant difference in capital costs," he says. "Trying to get money for capital projects right now is not easy, as everyone knows, so a smaller capital cost is a big attraction. The people that are looking forward in the industry are seeing [the hedging opportunity] as the real value in a system like this. Not only do you want a diverse group of byproducts so that you're in multiple markets, you're not living and dying by the corn and ethanol prices." EP

Kris Bevill is an associate editor at Ethanol Producer Magazine. Reach her at or (701) 850-2553.