Ethanol Stillage Separation: Wet Cake, Thin Stillage and Corn Oil
Decanters for whole stillage and disk stacks for corn oil: drier wet cake, cleaner thin stillage and an extra product.
Every dry-grind ethanol plant has to separate its whole stillage. Decanter centrifuges split it into a wet cake for distillers grains and a thin stillage that goes back to the front of the plant or on to the evaporators. A drier cake means less gas in the dryers, and a cleaner thin stillage keeps the evaporators running longer between cleanings. A disk stack separator on the syrup adds distillers corn oil as a product. Archer Separation supplies the decanters, the corn oil separators and the controls to run them.
The challenge: a hot, abrasive, high-volume stream
Whole stillage leaves the beer column hot, at high flow and with a significant load of fibre, germ and grit. The decanters run around the clock, and their wear parts, gearboxes and bearings decide how often the plant has to slow down. Small changes in cake dryness and centrate clarity add up to large differences in dryer energy and evaporator fouling.
Dryer energy
Every point of water left in the wet cake has to be evaporated in the dryer.
Evaporator fouling
Suspended solids in the thin stillage foul the evaporators and shorten the time between cleanings.
Uptime
Wear on the scroll, feed zone and solids discharge sets the maintenance schedule of the whole plant.
Typical process flow
Generic flowsheet for illustration. Every Archer system is designed to its own basis; ask us for one drawn for your plant.
How the process works
Feed
Whole stillage from distillation is collected in a stillage tank and pumped to the decanters at a steady rate.
Decanter
Duty and standby decanters separate the stillage into wet cake and thin stillage, with the scroll speed following the solids load.
Backset
Part of the thin stillage returns to cooking and fermentation as backset; the rest goes to the evaporators and becomes syrup.
Corn oil
An optional disk stack separator recovers corn oil from the syrup. The de-oiled syrup is blended with the wet cake ahead of the dryer.
What Archer supplies
HAUS stillage decanters
Decanters from our partner HAUS Centrifuge Technologies. Machine size and wear protection (hard-facing, tiles and replaceable inserts) are selected for each application.
Corn oil separators
Disk stack separators for oil recovery from syrup, sized for the syrup flow and temperature.
Controls and monitoring
Control panels with torque-based scroll control and IIoT remote monitoring of vibration, bearing temperatures and power.
Chemical and polymer systems
Chemical dosing and polymer systems where a process aid improves the separation, plus wastewater equipment for the rest of the plant.
Typical design basis
The figures below are typical for a dry-grind plant. Grain, grind, cook and fermentation all affect the stillage, so each installation is designed to its own basis.
| Whole stillage | Typically 10–14 % total solids |
|---|---|
| Wet cake | Typically 30–36 % DS |
| Thin stillage | Typically 5–8 % total solids |
| Suspended solids capture | Typically 85–95 % |
| Syrup | Typically 30–40 % DS from the evaporators |
| Corn oil | Recovered from the syrup with an optional disk stack separator |
| Machine selection | Size and wear protection selected for each application |
Typical values for illustration only. Performance depends on the stillage and is confirmed for each plant.
Why Archer Separation
Decanters you can keep running
- Engineering, not just equipment. Our engineers draw the process, size the machines and write the control philosophy, then commission the system and train your operators.
- Our own design tools. EPLAN for electrical design, SolidWorks for 3D models, OpenFOAM for CFD and code_aster for FEA, so panels, skids and containers are checked before they are built.
- Testing before you buy. Stillage samples are tested for solids, settling behaviour and oil content, so the decanter and separator sizes are based on your plant, not a catalogue.
- Rental and demonstration unit. Our containerized decanter can run on your site, on your material, before you commit to a permanent plant.
- Local support. Service and spare parts from our team in Canada and the US, with remote monitoring to tune and troubleshoot from our office.
Related pages
- Decanter Centrifuges: how decanters separate solids and liquids
- Disk Stack Centrifuges: separators for corn oil recovery
- HAUS Centrifuge Technologies: our decanter and separator partner
- Control Panels: panels that run and protect your machines
- Remote Monitoring: vibration, temperature and power trends from our office
- Screw Conveyors: moving wet cake to the dryer