Alfa Laval specializes in heat transfer, fluid handling and separation technologies, serving the ethanol, food and brewery industries. Because of the company’s diverse customer base, Alfa Laval can utilize its technologies cross-industry. One such technology is the Prodec 65 Oil Plus Skimmer, a two-phase decanter that helps ethanol producers collect 99% of the free oil found in the whole stillage.&nbsp;Prodec Oil Plus improves DCO yields by 25% to 40% when incorporated into the front end of the production process, according to the company. Yields vary by plant, says Dennis Schoenwald, business development manager – Ethanol and Biofuels Technologies with Alfa Laval. Dakota Spirit Ethanol, an 80 MMgy plant located near Spiritwood, North Dakota, installed Prodec in October 2024 and has seen yield increases between 25% and 30%, according to Brian Markegard, senior process engineer at Dakota Spirit, owned by Harvestone Low Carbon Partners.Most ethanol plants extract 0.8 to 0.9 pounds of DCO per bushel of corn, with high-yield plants extracting around 1 pound per bushel, but Schoenwald says even high-yield plants have seen significant production boosts. Temperature, use of a demulsifier, the amount of oil present in the corn crop or the fermentation process can all impact oil yield. Schoenwald credits Greg Maimares, sales representative for Applied Material Solutions, with supplying the demulsifier that releases the free oil so it can be captured by Alfa Laval’s technology.Through testing and analysis, Alfa Laval can give producers an accurate estimate of oil yield increase with Prodec Oil Plus, which helps producers determine whether the investment makes sense financially.&nbsp;“The reason for the large-scale test is everybody’s been dealing with the syrup, which is like 70 to 100 gallons a minute per machine,” says Stephen Ludes, a sales manager focused on agricultural processing at Alfa Laval. “Now you’re telling everybody that you need to put it through the full whole stillage flow, which, for a 60 million-gallon plant, is roughly 600 gallons a minute. If you’re a 100 million-gallon plant, you’re 1,000 gallons a minute. It’s a big capex upfront, so they need to justify the recovery and return in order to make the investment.”&nbsp;Alfa Laval verifies its estimates in the lab. “We do a rough 5- or 10-minute spin down, depending on whatever their standard lab procedures are at the plant, and spin it down just to get a value of where we’re at and because of the knowledge we’ve gained over the last two to three years, we already know how much [yield] that’s going to lead to,” Ludes says.Free oil is often incorporated into the solid material in the whole stillage as the whole stillage decanters dry out the cake. The remaining liquid is sent to the evaporators, concentrated and sent to disc stacks or tricanters for oil extraction. Schoenwald explains that implementing Prodec Oil Plus on the front end of the process after the beer column is the most “valuable” location, rather than extracting DCO from the syrup. Although Prodec Oil Plus can work at the back end of the process, where disc stacks and tricanters are usually employed, the yield bump is only 5%. The turbulence later in the process binds the DCO into the DDGS, making it impossible to break those bonds. Ludes explains that oil extraction at the back end of the plant also has a role to play, because sometimes the heat from evaporators breaks those bonds and maximizes capture.&nbsp;“Why not get that oil before it goes to the whole stillage decanter before it becomes impregnated, and before you start creating unnecessary losses on the back end?” Schoenwald says. The Prodec 65 Oil Plus has some similarities to a standard whole stillage decanter, which is designed to make a drier cake and remove as much water as possible, using the different densities and gravities of oil and water, enabling skimming of the free oil off the top.DCO’s specific gravity is around 0.9, while water’s specific gravity is over 1. This difference speeds up the separation between the two substances. “In this particular case, we want two liquid phases,” Ludes says. “You’re getting the oil phase out, and we want the other phase to stay a liquid and pumpable so it can go right to your whole stillage decanters.”&nbsp;“This oil capture is super critical to the plant because it is paying lots of bills,” Schoenwald says. “I mean everybody is only getting maybe, at most, an additional 5% by adding another disk stack or a tricanter on the back end of syrup. [So,] that’s the beautiful thing about our technology in [terms of] our placement: We don’t have this extremely complicated bolt-on technology.”Plant Practice&nbsp; Schoenwald introduced the technology to Dakota Spirit’s management team in 2021. The plant had already been exploring the idea of removing the free oil from the whole stillage early in the process.“We knew that we were losing oil in our whole stillage,” Markegard says. “It was going out with the whole stillage into the DDG and never making it into our backset or our centrate, and ultimately into our syrup.”&nbsp;Before adding Prodec Oil Plus, the plant was able to maintain around 1 pound per bushel of DCO by using strategies such as replacing its hammer mills to make a finer flour. “We were looking for the next step to improve that recovery and felt like without additional technology, we weren’t going to get to where we would like to be,” Markegard says.&nbsp;Dakota Spirit had an existing relationship with Alfa Laval, using its decanter-style centrifuges for whole stillage. The project also looked like a “plug and play opportunity” that was easy to execute compared to other bolt-on technologies, according to Markegard.&nbsp;Dakota Spirit ran a year-long test with a full-size machine before purchase, which gave the plant the opportunity to create mass balance and assess how the technology would impact evaporators, DDGS and other elements of the production process. The facility’s team gathered helpful data after two months, but ran it for another 10 to account for any variables that could impact performance.&nbsp;Dakota Spirit was among the first ethanol producers to run a test of Alfa Laval’s larger Prodec Oil Plus skimmer. “We wanted to figure out what one of our bigger machines would look like in a commercial setting that would take a commercial flow and Dakota Spirit was that candidate at that time,” Schoenwald explains.Executing Installation&nbsp; Installation requirements include the decanter, as well as a surge tank to hold the whole stillage and a surge tank for storing corn oil, in addition to some pumps and venting equipment. “Compared to other solutions, ours is about as simple as it gets from that standpoint—from an installation perspective,” Ludes says.&nbsp;The space requirements for the equipment can be a significant challenge when working on installation, he explains. The Prodec Oil Plus decanter must be located above the ground floor, so the de-oiled whole stillage can drop down into a surge tank after going through the decanter. Some producers have the space available already, but those that don’t may need to construct another building or a second-floor mezzanine level. “They’re basically taking the beer columns and dropping them down, feeding it to these machines and then taking what comes out of here and feeding it to the whole stillage rather than going straight from the beer columns to the whole stillage to decanters,” Ludes says. “All they’ve done is add this step in this little block in front of it.” The return on investment for Prodec Oil Plus is usually estimated at around two years, though it could be longer if a new building is needed to house the machinery.Dakota Spirit did not need to install a new building, but installing the technology in an existing building brought its own challenges, as the engineers had to navigate the process layout around existing pipe racks and electrical cabinets. Markegard says Dakota Spirit’s personnel worked together to map out the project before going into the engineering process; and Nelson Baker Biotech translated the management team’s vision for the installation into reality.The engineering firm designed redundant pipework so that the whole stillage flow can be redirected back to its normal course without interruption, in the event that the oil skimmers need to be taken offline for any reason.Ludes breaks down the impact DCO yields make on a producer’s bottom line. For example, if a 60 MMgy ethanol plant’s DCO yield is at 0.95 pounds per bushel before installation, a 30% increase brings the yield up to about 1.25 pounds per bushel, bumping up DCO production by 7 million pounds of oil each year. If the DCO price stands at $0.50 per pound, then the producer receives $3.5 million in additional revenue. “That’s why, whether it’s us or any other technology, they’re chasing corn oil, because that’s a lot of money per year,” Ludes says.&nbsp;As a lucrative product for ethanol producers, even a 2% increase brings significant profit. Producers must consider that not every piece of technology will be worth the investment. “I’d say every plant’s dynamics are different, so what you know, using the data to instruct what technology is best for that plant is the way to go,” Markegard says. “Whatever makes the most money.” Author: Katie Schroeder&nbsp; katie.schroeder@bbiinternational.com &nbsp;

2025-05-30 - Capturing Free Oil (Ethanol Producer Magazine)

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Alfa Laval’s DCO extraction technology captures free oil on the front end of the ethanol production process.

Capturing Free Oil

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