How it works
A decanter centrifuge is a horizontal rotating bowl with a co-rotating screw conveyor (scroll) turning at a slightly different speed. Slurry is fed into the bowl, where the centrifugal field — many times gravity — drives the denser solid particles outward to the bowl wall, where they accumulate as a liquid-saturated sediment. The clarified liquid forms a rotating annular pond and flows toward the overflow weir, while the screw, turning at a small differential speed relative to the bowl, scrapes the sediment along the wall toward the conical end and lifts it out of the pond, where it drains further before discharge.
Two things therefore happen at once and interact: sedimentation of particles out of the flowing slurry, set by bowl speed, particle size, and density difference; and sediment build-up and transport, where the cake compacts (a compressible, hindered-settling material) and is conveyed out. Capture of fine particles depends on the centrifugal force and the residence time in the pond; cake dryness depends on how long the sediment is worked and compacted before it leaves. This is an inherently dynamic, transient process — the cake builds up over time toward a steady state.
The model
Dyssol Pro models the decanter dynamically at the population level: it splits the machine into two coupled zones — a sedimentation zone and a sediment zone — and solves the unsteady mass and volume balances, so it resolves transient cake build-up and the approach to steady state rather than just a static split, at every time point of the flowsheet.
In the sedimentation zone the flowing slurry passes a series of well-mixed compartments, each applying a time-dependent grade efficiency — set by bowl speed, particle size and the solid–liquid density difference, liquid viscosity, and the bowl geometry — that settles solids out toward the wall. What fails to settle within the pond residence leaves with the clarified centrate; what is captured passes into the sediment zone.
There the settled material builds up as a compressible, liquid-saturated cake — with hindered settling and a gel-point transition from suspension to sediment — and the screw conveys it toward discharge at its differential speed, so cake dryness follows from how long the sediment is worked before it leaves. On this basis Dyssol Pro covers continuous centrifugal dewatering from counter-current and co-current decanters to high-G fine-bowl and three-phase machines, and even feed-specific behavior beyond the standard description can be brought into the flowsheet.
Equipment this model can represent
Any continuous centrifugal dewatering duty producing a dry cake and a clarified centrate.
Counter-current decanters
Slurry and sediment move in opposite directions (the classic configuration this model represents).
Co-current decanters
Feed and sediment move the same way, gentler on flocs.
High-G / fine-bowl decanters
Long, slender bowls at high speed for fine-particle clarification.
Three-phase (tricanter) decanters
Separate two liquids plus solids simultaneously.
Typical engineering studies
What teams investigate with the decanter model.
Centrate & cake prediction
Predict residual solids and PSD in the centrate, and cake solids for a given decanter setting and feed, including the transient.
Speed & pond-depth studies
Study bowl speed, differential speed, weir/pool depth, and feed flow against centrate solids and cake solids.
Dynamic upsets
Study feed-solids upsets, startup, and the approach to steady cake build-up.
Calibration & scale-up
Calibrate settling, cake transport, and sediment-compression parameters to measured performance, then support validated scale-up or transfer to new feeds.
Flowsheet coupling
Couple the decanter to upstream thickening and downstream cake-handling units in one flowsheet.
Existing application example
Industrial zeolite production
End-to-end catalyst process with synthesis, decanter washing/concentration, spray drying, and two-stage rotary-kiln calcination. Dyssol Pro connected surrogate synthesis models with dynamic downstream units in one flowsheet.
Technical FAQ
How does a decanter centrifuge separate solids from liquid?
A rotating bowl drives denser solids to the wall as a sediment while clarified liquid overflows a weir, and a screw turning at a small differential speed conveys the cake out of the pond. Dyssol Pro models exactly this with coupled sedimentation and sediment-transport zones, resolved over time.
Why is my decanter centrifuge producing wet solids?
Wet cake means too little compaction or residence in the sediment zone — often too high a feed rate or too low a differential speed. Dyssol Pro models the compressible, liquid-saturated cake build-up, so you can predict cake solids and tune differential speed and flow to dry it.
How can I improve clarification efficiency in a decanter?
Clarity improves with higher bowl speed, lower throughput, and a deeper pond for more residence. In Dyssol Pro these are model parameters, so you study centrate clarity against bowl speed, flow, and weir radius to find the right setting.
What causes high solids carryover in the centrate?
Fine particles that don’t settle within the pond residence escape with the centrate. Dyssol Pro’s size-resolved grade efficiency shows which fines escape, so you can study how more bowl speed or less flow captures them.
How do bowl speed and differential speed affect separation?
Bowl speed sets the centrifugal force (and thus capture and clarity); differential speed sets conveying rate and cake residence (and thus dryness). Dyssol Pro takes both as parameters and models their distinct effects, so you can balance clarity against cake dryness explicitly.
How can I reduce polymer consumption in centrifuge operation?
Polymer flocculates fines into larger, faster-settling aggregates. Dyssol Pro represents its effect through a coarser effective feed PSD, so you can study how much aggregation is actually needed for target capture and aim for the minimum dose.
What parameters influence cake dryness in a decanter centrifuge?
Cake dryness is governed by residence and compaction in the sediment zone — differential speed, feed flow, and the compressibility of the solids. Dyssol Pro’s dynamic sediment-zone model predicts cake solids as a function of those settings.
How do I size a decanter centrifuge for slurry treatment?
Sizing balances throughput against required clarity and cake dryness. In Dyssol Pro you run the model at the feed conditions and read centrate and cake, giving you the duty an operating point must meet.
How can I optimize decanter operation for changing feed solids?
Robust operation under changing feed solids means picking bowl speed, differential speed, and flow with enough margin that cake compaction and clarification still meet spec across the expected concentration swings, rather than tuning to the average feed alone. Dyssol Pro’s dynamic model lets you impose those feed-concentration transients and watch cake and centrate respond, so you can find the settings that hold up across the whole range before committing them to the plant.
Why does my decanter cake quality change during operation?
Cake quality evolves as the sediment builds up toward steady state and with feed variation. Dyssol Pro is a transient model, so it shows that cake build-up over time and helps you tell a normal approach-to-steady-state from a genuine upset.
How do I reduce wear in a decanter centrifuge?
Wear is driven by abrasive solids at high bowl speed, so it is limited by running at the lowest speed and solids load that still meet the separation duty. Dyssol Pro computes the speed and load an operating point needs, so you can steer toward the gentler settings.
How does feed particle size affect decanter performance?
Finer feed is harder to capture and tends to escape in the centrate. Dyssol Pro resolves the PSD and computes a size-dependent grade efficiency, so you see directly how feed fineness shifts clarity and recovery.
How can I improve solids recovery in a decanter?
Recovery improves with more centrifugal force and residence — higher bowl speed, lower flow. In Dyssol Pro you study recovery against those settings and the feed PSD to find the operating point that captures the required fraction.
What causes foaming in centrifuge operation?
Foaming comes from surfactants and entrained air in the feed forming stable gas–liquid films. It is controlled by adding antifoam agents, reducing air entrainment at the feed inlet, and de-aerating the slurry before it enters the bowl.
How do I optimize pond depth in a decanter centrifuge?
A deeper pond gives more clarification residence but a shorter drying beach, trading clarity against cake dryness. Dyssol Pro takes the weir radius (pond depth) as a parameter, so you can study that trade-off and pick the depth that meets both targets.
What is the effect of feed flow rate on cake dryness?
Higher feed flow shortens residence, giving a wetter cake and poorer clarity. Dyssol Pro lets you vary the feed flow and read cake solids and centrate clarity off the dynamic model to set the throughput.
How can I reduce torque overload in a decanter?
Torque overload comes from too much cake load on the screw. Dyssol Pro models the cake build-up that drives torque, so you can avoid the feed-rate and differential-speed combinations that let cake accumulate and overload the screw.
How do I troubleshoot poor liquid clarity after centrifugation?
Poor clarity means fines are escaping the pond. In Dyssol Pro you study which size classes leave in the centrate against bowl speed and flow, which localizes whether the cause is insufficient force, too much throughput, or a finer feed.
How can I model sedimentation and transport in a decanter centrifuge?
This is exactly the unit: a dynamic model with a sedimentation zone (time-dependent, size-resolved capture) coupled to a sediment zone (compressible cake build-up and screw transport), giving centrate clarity and cake solids over time inside the flowsheet.