The Benefits of Using a Tricanter for Corn Oil Recovery

A case study of a multi-facility ethanol company’s successful incorporation of Tricanters into its production portfolio. Numerous benefits for DCO recovery were found, including cost reduction, enhanced versatility and lower maintenance.
By Bill Griffiths | February 23, 2022

With four South Dakota facilities recovering corn oil, Glacial Lakes Energy LLC was faced with the challenge of selecting the primary separation technology for one of its plants. The company chose a Tricanter over its familiar disc-stack technology for the Aberdeen facility and doubled corn oil production the day it began operating. Even though the Tricanter machine is more expensive, GLE Director of Operations Pat Hogan said the additional cost was justified because of its ease of operation, higher yield, lower maintenance, increased uptime and cleaner oil.

Glacial Lakes Energy has four facilities in operation in South Dakota—Aberdeen, Huron, Mina, and Watertown—all overseen by Hogan, who is based in Watertown. All four facilities are located within a two-hour driving radius. Each plant has its own plant manager, production manager and maintenance manager responsible for taking care of and running their equipment.

Glacial Lakes Corn Processors (GLCP), was formed in 2001 as a South Dakota Cooperative comprised of more than 4,100 shareholders. GLCP owns 100% of GLE and its four ethanol plants.

GLE-Watertown, an original 40 MMgy nameplate facility, became operational in August 2002. In 2007, the facility was expanded and currently produces more than 130 MMgy of ethanol. GLE-Mina became operational in June 2008 as a 110 MMgy facility, and is now operating at 140-plus MMgy. In December 2019, GLE purchased two additional ethanol production facilities located in Aberdeen and Huron, South Dakota. The Aberdeen plant currently produces about 50 MMgy. The Huron plant currently produces about 40 MMgy.

Combined, GLE’s ethanol plants purchase more than 125 million bushels of corn per year, and produce 360-plus MMgy of ethanol; 918,000 tons of feed products/distillers grains and 51,000 tons of corn oil per year.

The Challenge and Solution
GLE was previously using a disc-stack separator at Aberdeen for oil recovery and separation. Because the machine was simply too small and not producing at an acceptable rate of recovery with low oil yields, Hogan was convinced the production could be stronger with upgraded equipment.

“This presented us with the opportunity to either install more disc-stack units, or upgrade to a different technology,” Hogan said, explaining that the choices were a Flottweg Tricanter, or more disc-stack separators from another supplier.

“From a straight oil-separation perspective, both are good technologies,” Hogan said. “If you have oil to pull out of a stream, they will both pull it out equally and as efficiently. However, I lean heavily toward the Tricanter for corn oil ethanol recovery.”

Hogan chose the Tricanter for the Aberdeen plant, but continues to use the disc-stacks for two of the other GLE facilities. The size of each facility is a determining factor for selecting technology and the number of units needed, Hogan said.

• The Mina plant (140+ MMgy) is using two Tricanters.

• The Watertown plant (130 MMgy) is using three disc-stacks.

• The Aberdeen plant (50+ MMgy) is using one Tricanter.

• The Huron plant (40 MMgy) is using one disc-stack.

Even though the Tricanter is initially more expensive, sometimes by as much as 30-40%, Hogan said there are five reasons why he prefers the Tricanter over the disc-stack technology for corn oil recovery:

1. Ease of operation,

2. More yield with regard to production uptime,

3. Lower maintenance,

4. Less downtime, and

5. The Tricanter produces cleaner oil than disc stacks.

“The number one reason that I chose the Tricanter is because I believe it is easier to operate,” Hogan said. “All the plants already have similar types of horizontal bowl decanters. In addition to the ease of operation, the Tricanter is less finicky than a disc-stack, which basically means that on a daily, weekly and monthly basis, Tricanters require much less maintenance. If you take care of the machine, it only requires an annual rebuild. The disc-stack machines require quarterly rebuilds in addition to the annual rebuilds.”

Hogan noted that the Tricanter requires a weekly or bi-weekly cleaning, which equates to taking it out of service for 4 or 5 hours for cleaning, while the disc-stack machines need multiple water flushes daily in addition to weekly cleanings.

The annual maintenance costs for the disc-stack and Tricanters are relatively similar, with the Tricanter being marginally less expensive. But the Tricanter provides more uptime, according to Hogan, and is more forgiving during operations.

“For example, we feed these machines syrup which is pulled from our evaporators, and if you perform hydroblasting or CIP on your evaporators, the disc-stacks must be taken offline for a few hours during this procedure to prevent disc blockage,” Hogan explained. “However, the Tricanter will just gobble that up, and you can keep it running. This provides more uptime and more production.”

According to Hogan, the five benefits justify the additional cost incurred to purchase the Tricanter technology.

“Now, we have some really good folks who take care of the disc-stacks in our two facilities, and they tend to make it look easy. But I’ve been in plants that were perhaps not as technically savvy, and I’ve seen how those disc stacks can create a lot of headaches if you don’t pay them 100 percent attention,” Hogan explained. “The Tricanter is just a lot more forgiving. There are fewer mechanical moving parts, whereas with the disc-stack there are a lot more little things that can go wrong with them.”

When Hogan began working with GLE, there were two facilities—Mina and Watertown—and each of them were using two disc-stack machines. Mina was in a similar position as Aberdeen in early 2021—the disc-stacks were not making very good oil and had low oil yield. 

“We had to make a choice to upgrade the system,” Hogan said. “At the time we considered whether to buy a couple more disc-stacks to increase their capacity or replace the disc-stacks with a Tricanter. We opted for two Tricanters. We doubled the oil yield as soon as we turned on the Tricanter.”

Since the two-disc stack machines were still operational, Hogan said they decided to leave one in Mina as a backup unit to use during weekly Tricanter CIP procedures. The second disc stack machine was installed in Watertown, a facility that now runs three disc-stacks, markedly improving their oil production with the increased capacity. In 2019, the Huron and Aberdeen plants were purchased by GLE. Huron already had a disc-stack that was sufficient for that plant, so it wasn’t upgraded or replaced. The Aberdeen unit, however, did not have enough capacity to support the plant, so one Tricanter was installed to replace it.

How the Tricanter Works
This three-phase centrifuge separates the maximum amount of distillers corn oil from syrup for added revenue. The Flottweg Tricanter features simple operation for cleaner oil and more uptime compared with standard separators. The high oil yield provides a rapid return on investment.

The Flottweg Tricanter reduces solids debris and fatty acid content to produce cleaner recovered oil that can be sold as a feed ingredient or biodiesel feedstock that can earn a premium price over other forms of oil.

Even when you sell non-food grade corn oil as a separate, higher-value product, the fat content in the DDGS remains above 8.5% and delivers an average pro-fat content in excess of 35%.

Classic bioethanol plants produce ethanol, solids (DDGS), and the residual syrup, created from evaporating and drying the thin stillage. However, modern, innovative plant operators utilize an additional option for raw material extract. After passing through the decanter, the thin stillage is mainly free of larger solids (still containing fines), but not from valuable oil. For example, to separate corn oil in corn-based ethanol plants, Tricanters are commonly used.

The structure and function of the Tricanter are similar to those of a decanter (two-phase separation). The decisive difference between these two machines is in the way that the liquid is discharged. A Tricanter uses two liquid phases: a “heavy” liquid phase (higher density and discharged under pressure) and a “light” liquid phase (lower density and discharged without pressure). This is the principle used to separate oils from the thin stillage to yield yet another raw material that can be used, for example, to manufacture biodiesel. 

An adjustable impeller sets the separation between the light phases. This is traditionally done by a static weir plate. With an adjustable impeller, the light phases can be precisely set while the machine is running to get the best possible oil quality. This can be done manually or automatically with a Flottweg control system.

The Tricanter offers many advantages for corn oil recovery:

• Combining the processing steps eliminates the need for additional separation stages, which results in considerable cost savings.

• In addition to its high selectivity, the Tricanter is versatile. It can adapt to changing inlet conditions at any time.

• It offers the highest possible phase separation and unparalleled flexibility due to the adjustable impeller.

• Maintenance is similar to that of the decanter.

Results for Glacial Lakes Energy
Hogan said he prefers the Tricanter technology in all cases for corn oil recovery, although sometimes the cost is not justified. “If the Huron unit had a catastrophic failure, for example, I would replace it with a Tricanter,” he said. “But for now, the extra expense can’t be justified.”

The newest installation in Aberdeen is already producing significant improvements in yield. Previously, the plant was producing approximately 0.55 pounds of corn oil per bushel of corn. “As soon as we turned the Tricanter on—day one—production improved to .81 pounds,” he said. “This clearly demonstrates the improvement in capacity.”

For now, GLE will continue to use the current technology in place in its four South Dakota plants. “The disc-stacks are reliable, so the chance of a catastrophic failure is fairly low,” Hogan said. “But this is a good solution for our Aberdeen plant.”

And for Hogan, the additional cost of the equipment is clearly justified with the ease of operation, low maintenance, higher yield, less downtime and cleaner oil.

“I’m asked this question all the time when I put in a capital request for a Tricanter—the board will inevitably ask why I prefer the Tricanter over the disc-stack, particularly with the difference in purchase price,” Hogan explained. “I go through this whole scenario of explanations each time. Honestly, sometimes it just comes down to personal preference. I’m sure there are some people in the industry who would prefer the disc-stack technology. For me, I’ve run these Tricanters at four different facilities and they just run. You install them, take care of them, and they just run. For me, that’s the most important thing. It’s that simple.”

Author: Bill Griffiths
Head of Sales – Edible Fats & Oils
Flottweg Separation Technology
[email protected]