Decanter upgrade improves ethanol separation efficiency

At EverGrain’s Missouri facility, corn is processed into renewable ethanol fuel. A key stage in production is the separation of solids and liquids, where decanter centrifuges recover distiller’s grains from thin stillage. Stable separation performance is critical for maintaining ethanol yield, reducing downstream drying requirements, and controlling energy consumption.

Plant operators faced recurring operational challenges caused by fluctuating feedstock conditions. Variations in flow rates, solids concentration, and viscosity frequently disrupted the separation process, making it difficult to maintain consistent pond depth inside the decanter centrifuges. Operators relied on manual adjustments, which limited responsiveness during rapid process changes.

The instability affected cake dryness and centrate clarity, while increasing power consumption and operational intervention. The plant also needed to minimise equipment wear and maintain production flexibility as market and feedstock conditions changed.

Automated pond depth control deployed on existing decanters
To address these issues, EverGrain implemented the Alfa Laval PondCtrl upgrade from Alfa Laval on its existing decanter centrifuges. The system introduces automated, real-time pond depth regulation during operation. Instead of relying on fixed weir plates, the upgrade uses an adjustable paring disc that allows operators to modify pond depth directly from the control system without stopping the machine.

The upgrade was selected because it could adapt continuously to changing process conditions while avoiding the downtime associated with manual mechanical adjustments. The ability to fine-tune separation parameters during operation also allowed the plant to optimise performance according to production priorities such as yield, energy efficiency, or product quality. According to the project description, the system also reduced the risk of liquid overflow at solids discharge and improved operational stability during start-up and shutdown sequences.

Separation efficiency and energy performance improved
Following deployment, EverGrain reported measurable improvements in separation efficiency and process stability.
Cake dryness increased by up to 2% total solids, reducing the load on downstream drying equipment. Solids carryover into the centrate stream decreased by 15–20%, improving liquid clarity and overall separation quality. The plant also achieved a 5–10% reduction in power consumption.

The operational improvements contributed to higher uptime, fewer manual interventions, and reduced mechanical wear on the centrifuges. By improving process control without replacing existing equipment, the upgrade enabled the plant to increase operational flexibility while supporting more efficient ethanol production during fluctuating operating conditions.

Edited by Evgeny Churilov, Induportals Media - Adapted by AI.

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