The Essential Role of Decanter Centrifuge in Ethanol Production Process

May 25,2024

Ethanol production stands as a sophisticated process demanding advanced machinery to uphold both efficiency and quality standards. The procedure revolves around dry milling grains like corn, wheat, barley, and rye.

Within this intricate process, starch, essentially sugar, undergoes fermentation to yield ethanol, accompanied by the production of Distilled Grain + Soluble (DDGS) as a consequential by-product.

Decanter Centrifuge

DDGS Industry Insight

To enhance revenue streams, many ethanol producers have expanded their product offerings to include a variety of sectors such as biofuels, plastics, fertilizers, carbon dioxide, disinfectants, and animal feed.

Distillers dried grains with solubles (DDGS) constitute a key by-product of the brewing industry, with approximately 98% sourced from ethanol plants and the remaining 2% from the alcoholic beverage industry.

Mainly derived from corn and, to a lesser extent, wheat & rice, DDGS production has witnessed substantial growth since 2000, reaching an approximate output of 35 million tons in 2011, alongside a notable surge in exports.

In the United States, a significant portion of DDGS finds its way into dairy and beef cattle feed, with approximately 20% allocated to swine and poultry feed.

Ethanol and DDGS emerge as final products in the production process, with decanter centrifuges utilized for lees dehydration post-ethanol distillation. Additionally, should the need arise, energy can be harnessed from the liquid phase by implementing a biogas plant.

DDGS Industry Insight

DDGS Production Process

Upon arrival at the mill, grains carry foreign matter such as dust, straw, and stalk residue, necessitating thorough cleaning prior to storage and further processing.

Utilizing equipment like pre-cleaners, destoners, and magnetic separators effectively removes impurities. Once cleaned, the grains are ground into powder using hammer or roller mills.

Subsequently, the ground grains, along with water and amylolytic enzymes, undergo mixing and cooking at temperatures ranging from 40 to 60°C. The slurry then progresses through a jet cooker, where temperatures are maintained at 110 to 120°C, culminating in the liquefaction tank at 90°C.

Throughout this phase, starch’s long chains undergo hydrolysis, breaking down into smaller chains, thereby augmenting sugar content and diminishing viscosity.

DDGS Production Process

Key Steps

Preceding fermentation, the slurry necessitates cooling to 32°C. Once this optimal temperature is attained, fermentation initiates. Within the fermenter, the slurry combines with water and activated yeast, catalyzing the conversion of grain sugars into ethanol and carbon dioxide. Depending on desired alcohol concentrations, fermentation typically spans approximately two days.

The resultant fermented mixture undergoes separation in a distillation column, where alcohol is isolated from water and other impurities, yielding nearly 95% pure ethanol.

Concurrently, the solid-liquid mixture produced during fermentation proceeds to a decanter centrifuge for dehydration. The solid phase undergoes dehydration within the decanter centrifuge before advancing to the drying phase.

During drying, the liquid phase transforms into thick pulp via evaporation and is reincorporated into the wet cake, subsequently directed to a tube bundle dryer to achieve a moisture content of roughly 10%-14%.

The dehydration process plays a critical role in mitigating grain combustion risks, altering color, preserving nutrient integrity, and moderating their degradation rate.

For cattle feed applications, the decanter solids output can be utilized directly without the need for drying. However, for sheep and fish feed, drying is essential to ensure optimal quality and suitability for consumption.

Key Steps

DDGS Involved Processing Steps

The structure and working principle of the decanter centrifuge (taking DDGS production as an example)


The decanter centrifuge comprises three primary components:

Drum Section: This section encompasses the cylinder and cone, serving as the housing for the materials undergoing separation. As the drum rotates, centrifugal force aids in the separation of solids and liquids.

Screw Conveyor: Positioned within the drum. As the drum rotates, the screw conveyor facilitates the continuous removal of solids, ensuring efficient separation.

Drive Mechanism: The driving device, comprising a motor and gearbox, orchestrates the rotation of both the drum and the screw conveyor. By adjusting the differential speed between these components through the gearbox, operators can fine-tune the separation process according to specific requirements, optimizing efficiency and performance.

DDGS Involved Processing Steps

Working Principle:

In the context of DDGS production, the decanter centrifuge operates as follows:

Feed Introduction: The mixture of fermented solids and liquids, obtained from the fermentation process, is introduced into the decanter centrifuge.

Centrifugal Separation: Upon entry, the drum rapidly rotates, generating centrifugal force. This force causes the denser solid particles to migrate outwards towards the drum’s periphery, while the lighter liquid phase remains closer to the center.

Screw Conveyance: As the solid particles accumulate along the drum’s periphery, the screw conveyor facilitates their continuous removal towards the discharge port. This ensures the efficient extraction of solids from the liquid phase.

Liquid Discharge: Simultaneously, the clarified liquid phasetravels towards the center of the drum and exits through a separate outlet.

Fine-Tuning: The speed differentials between the drum and the screw conveyor can be adjusted via the gearbox, allowing operators to optimize separation efficiency based on factors such as particle size, density, and desired productquality.

Working Principle

Huading Centrifuge: Optimizing DDGS Feed Production

Huading’s decanter centrifuge is designed for efficiency and adaptability. It automatically adjusts to varying solid load levels, enhancing stillage dehydration. Compared to standard models, it increases solid recovery rates by 20-30%, thanks to its innovative design.

Key Features

Enhanced Separation: High separation factor and optimized performance ensure superior separation.

Improved Solid Recovery: High recovery rates reduce evaporator maintenance costs.

Versatile Models: Available in capacities from10-40m³/h of a single unit, accommodating matching various production scales.

Effortless Operation: Automated features streamline processes, minimizing manual intervention.

Responsive Drive System: Fast response times and high torque ensure reliable performance.

Longevity and Durability: A high wear-resistant protection system and premium materials guarantee durability.

Space-saving Design: Compact and user-friendly, saving valuable floor space.

24/7 Support: Reliable assistance and guidance ensure uninterrupted operation.

For more on how the Huading decanter centrifuge optimizes DDGS feed production, contact us today.

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