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The Working Principle of the Decanter Centrifuge

April 11, 2024

The decanter centrifuge, sometimes called a solid bowl centrifuge, is an essential piece of equipment for effectively separating solids from liquids using a continuous and fast-moving rotating mechanism. Many industries find this device extremely useful, including biosolids wastewater treatment and the chemical and mining industries. Its primary use is in 2-phase dewatering of slurry systems, where it extracts solid components from liquid mixes. The decanter centrifuge enables a strong separation process using high-speed rotating forces, which helps improve production and quality control. It optimizes operations and promotes environmental sustainability.

Working Principle of Decanter Centrifuge

Gravitational forces accelerate the separation of solid and liquid components inside a slurry, and this is the basic idea that is included in the decanter centrifuge working principle. A decanter centrifuge speeds up the process of gravitational settling by rapidly spinning the container, in contrast to static containers or clarifiers, which are examples of classic 1xG separation methods.


The separation process is accelerated from hours to seconds due to the centrifuge's high-speed rotation, which creates a powerful G-force greater than three thousand times gravity. Modern decanter centrifuges utilize a counter-current design. The denser solid particles condense and settle to the bottom of the inner drum in a two-stage mechanism before being discharged via the solids discharge end. At the same time, the center, or cleared liquid, is redirected to the other

end to be removed.


The 3-phase decanter centrifuge includes an integrated baffle system. Using this technique, the lighter phase fluid—usually oil—is kept separate from the water. As the oil flows between the baffles, it settles to the top, where it may be more easily extracted. Decanter centrifuges are essential in many industries due to their rapid and accurate solid-liquid separation.

Shenzhou - continuous three phase decanter centrifuge for oil separation Centrifuge & Separator

3-phase decanter centrifuge

Key Components of Decanter Centrifuge

The Feed Material Introduction

To start the decanter centrifuge's symphony of operations, the feed material is introduced through a feed pipe inlet at one end of the unit. At this crucial stage, the process begins to separate the heavier particles from the liquid matrix using centrifugal forces generated by the bowl's high-speed spinning. An essential function in many different industries, including wastewater treatment, chemical processing, and mining, effective solid-liquid separation is achieved through a series of events that begin with the precise introduction of feed materials into the centrifuge.

Centrifugal Separation

In the decanter centrifuge, the entering material is transformed using centrifugal force. The material's larger particles aggregate along the inside wall of the spinning bowl as the bowl spins at a high speed, driven through the liquid phase. The rapid rotation of the bowl creates centrifugal force, which efficiently separates solids from liquids. Centrifugal force dynamics capture heavier particles as they are propelled toward the bowl's inner wall and efficiently separate solids from liquids.

Variable Frequency Drive

A decanter centrifuge's Variable Frequency Drive (VFD) is an essential part that allows for exact regulation of the centrifuge's spinning speed, which is vital to the centrifuge's efficient functioning. The variable frequency drive (VFD) is crucial for optimum performance since it regulates the electrical power frequency that the centrifuge motor receives on the fly. By adjusting the frequency, precise control may be achieved, guaranteeing that the centrifuge runs at the optimal speed for effective solid-liquid separation.

Scroll Conveyor

The scroll conveyor, which operates inside the decanter centrifuge bowl, performs a crucial role by rotating. Its speed is not the same as the bowl. An important part of the dynamic interaction that highlights the scroll's scraping motion is the deliberate variation in pace. The scroll and the bowl operate at different speeds to loosen and remove particles stuck inside the bowl.

To keep the separation process efficient, the scraping motion of the scroll is essential. In addition to removing particles, the scroll conveyor guides them to the centrifuge conical's solids discharge portion.

Central Movement

The center, a liquid component of the decanter centrifuge, moves counterclockwise in the complex ballet, opposite the solids' trajectories. A well-planned network of linked pipes using Pascal's Law produces this coordinated counterflow. The well-engineered coupling assures a systematic and regulated movement of the liquid of pipes, and this exact counterflow dynamic is further enhanced by Pascal's Law, which governs fluid behavior. Importantly, the accumulating particles keep the solids discharge end shut, so no undesirable mixing occurs.

Solids Retention

The complicated process of controlling the differential speed of a decanter centrifuge determines the length that solids are subjected to g-force within the machine, which in turn controls the machine's efficiency. Dewatering is an important part of the centrifuge's operation, and this sophisticated control system directly impacts it. Adjusting the differential speed is like adjusting the centrifuge's settings; it controls the time solid particles spend within the machine. A crucial component of the machine's effectiveness in drying the separated solids is an extended retention period caused by g-force, which leads to drier solids.

Decanter Centrifuge In Sludge Dewatering

Decanter centrifuges have significant advantages in dewatering compared to procedures that thicken the sludge. When using a decanter centrifuge for mechanical dewatering, the volume may be reduced by an astounding 95%, with dry solids concentrations ranging from 15% to 35%. Alternatively, a solids concentration of 3–7% and an 80% volume decrease are the outcomes of sludge thickening. A drier cake product and substantial savings in treatment, handling, and disposal expenses result from dewatering's effectiveness in removing more water.


The Biosolids Technology Fact Sheet from the EPA emphasizes the many benefits of dewatering. It enhances air drying and stabilization processes, decreases fuel needs for incineration or heat drying, minimizes ponding and runoff, removes free liquids before landfill disposal, and reduces volume, resulting in cost savings in storage and transportation.


Decanter centrifuge is a vital machinery for different kinds of businesses because of how well they separate solids from liquids and how well they dewater sludge. They are essential for peak operating efficiency because of the substantial volume reduction, dry solids concentration, and cost savings made possible by their complex design and precise control mechanisms.

Looking for reputed manufacturers of Decanter Centrifuges? Shenzhou Machinery is a renowned name. With 30+ years of experience, we can help your industrial operations run more smoothly.

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