How it works
A disk-stack centrifuge spins a stack of more than a hundred closely spaced conical disks. The feed suspension enters at the outer radius and flows inward through the thin channels between the disks. Rotation imposes a strong centrifugal field, so every particle denser than the liquid is driven outward and downward onto the underside of a disk, then slides to the outer radius where the sediment collects and is discharged. The clarified liquid continues inward and leaves at the center.
The short inter-disk distance is the trick: a particle only has to settle across a thin channel before it reaches a disk surface, so even fine particles are captured at modest residence time. Capture therefore depends on both particle size and the density difference between solid and liquid — a larger particle or a denser solid settles faster and is caught more completely. Higher rotational speed, more disks, and lower throughput all sharpen the separation; high feed concentration hinders settling because particles get in each other’s way.
The model
DyssolPro computes a grade efficiency G(x, ρ) that depends on both particle size and solid density, using one of two disk-stack models. An optional Richardson–Zaki correction accounts for hindered settling at higher solids volume fraction. Solid and liquid phases and a PSD are required.
- Leung — A disk-stack model whose key fitting parameter is the acceleration efficiency μ — how fully the liquid is brought up to disk speed; separation scales with rotational speed, channel geometry, and the disk radii.
- Schubert — A two-step model combining separation at the suspension inlet (G₁) with separation inside the channels (G₂), each with its own sharpness and adjustment factor.
Equipment this model can represent
Any centrifugal clarification duty for low-to-moderate-solids suspensions of fine particles.
Clarifiers (solid-retaining)
Low solids load; periodic manual cleaning of the retained sediment.
Self-cleaning separators
The bowl opens periodically to eject accumulated solids automatically.
Nozzle separators
Continuous solids discharge through peripheral nozzles for higher solids loads.
Purifiers / concentrators
Liquid–liquid–solid duty, e.g. separating two liquid phases plus solids.
Typical engineering studies
What teams investigate with the disk-separator models.
Clarification prediction
Predict clarification efficiency and sediment/permeate splits for a given machine and feed.
Geometry & speed studies
Study capture versus rotational speed, disk spacing, channel count, and throughput.
Concentration effects
Use the Richardson–Zaki correction to study hindered settling on dense feeds.
Calibration & scale-up
Calibrate the acceleration efficiency or Schubert factors to measured performance, then scale up.
Multi-density separation
Resolve multi-density solid mixtures, since separation is computed per compound density.
Technical FAQ
How does a disk stack separator work?
Closely spaced rotating conical disks create a strong centrifugal field, so solids denser than the liquid settle the short distance onto a disk, slide outward, and collect as sediment while clarified liquid leaves at the center. DyssolPro reproduces this with a grade efficiency that depends on particle size and density, using the Leung or Schubert disk-stack model.
What is the difference between a disk separator and a decanter centrifuge?
A disk stack clarifies low-to-moderate-solids suspensions of fine particles; a decanter handles higher solids and produces a drier cake. DyssolPro offers both units, so you can model each for your duty and compare clarification against dewatering directly.
How can I improve fine particle removal in a disk separator?
Fine capture improves with higher bowl speed, more disks (shorter settling distance), and lower throughput. In DyssolPro these are model parameters, so you study how rotational speed, channel geometry, and feed flow move the fine end of the grade curve.
Why is my disk separator losing product in the reject stream?
If valuable solids report to the sediment unintentionally, the cut is set wrong for their size and density. DyssolPro’s G(x, ρ) shows exactly which size/density classes go where, so you can retune speed and flow to recover the product.
How does flow rate affect disk separator efficiency?
Higher flow means shorter residence and poorer fine capture. DyssolPro takes the volume flow from the stream and lets you study efficiency against throughput to find the rate that still meets your clarity target.
How do I choose between nozzle discharge and self-cleaning disk separators?
That choice depends on solids load and how the sediment is discharged — a machine-design decision. DyssolPro models the separation and the sediment’s liquid content rather than the discharge mechanism, so it informs the duty (how much sediment, how wet) that drives the choice.
What causes fouling in a disk stack centrifuge?
Fouling comes from sticky solids and precipitates building up in the stack — an operational effect the model doesn’t simulate. DyssolPro covers the separation performance; the upstream conditions that promote fouling can be studied in the connected flowsheet.
How can I reduce maintenance frequency for a disk separator?
Maintenance is driven by fouling and wear, which are mechanical and operational. DyssolPro doesn’t model them directly, but by helping you run at a lower-stress operating point (speed and throughput for the required clarity) it supports the process side of the decision.
How does particle density difference affect disk separator performance?
Capture scales with the difference between solid and liquid density, so denser solids separate more readily at a given size. DyssolPro uses densities from the materials database per compound, so density differences are built into the grade efficiency automatically.
How can I simulate liquid-solid separation in a disk separator?
This is the unit’s purpose: choose the Leung or Schubert model, set the geometry and speed, and DyssolPro returns the size- and density-resolved split between sediment and clarified liquid inside your flowsheet.
How do I optimize discharge frequency in a disk separator?
Discharge timing on a self-cleaning bowl is an operational cycle the model doesn’t represent. DyssolPro models the continuous separation and the sediment liquid content, which tells you how fast solids accumulate — the basis for setting that frequency.
Why is my disk separator producing unstable separation results?
Instability usually traces to fluctuating feed flow or concentration. In DyssolPro you impose those feed transients and, with the Richardson–Zaki correction, see how concentration swings move the efficiency — separating a process cause from a mechanical one.
How does viscosity affect disk stack separator performance?
Higher liquid viscosity slows settling and lowers capture. DyssolPro takes liquid viscosity from the materials database in the settling calculation, so temperature- or composition-driven viscosity changes show up in the predicted efficiency.
What causes solids buildup inside a disk separator?
Build-up comes from solids accumulating faster than they discharge — an operational effect outside the model. DyssolPro predicts the solids load reaching the sediment, which is the quantity that drives build-up, without simulating the deposit itself.
How can I reduce product loss during sludge discharge?
Discharge losses depend on the ejection mechanism and timing, which are operational. DyssolPro models the steady separation and the sediment’s liquid content, helping you minimize the liquid (and entrained product) leaving with the solids.
How do I choose the right disk spacing for separation?
Smaller channel height means a shorter settling distance and better fine capture, at the cost of capacity and fouling risk. In DyssolPro the channel height is a model parameter, so you study spacing against efficiency to find the balance.
How can I improve phase separation in a disk separator?
Phase separation improves with speed, residence time, and geometry. DyssolPro lets you tune rotational speed, throughput, and disk geometry and see the effect on the sediment/permeate split.
What is the effect of temperature on disk separator efficiency?
Temperature acts mainly through liquid viscosity and density — warmer, thinner liquid settles solids faster. DyssolPro uses those properties at the operating condition, so you can study temperature by running at the corresponding liquid properties.
How do I troubleshoot vibration in a disk stack separator?
Vibration is a mechanical issue (imbalance, deposits) that the model doesn’t represent. DyssolPro addresses the separation side; the vibration diagnosis stays with the machine.
How can I model centrifugal clarification of fine suspensions?
That is exactly what the unit does: a size- and density-resolved grade efficiency with an optional Richardson–Zaki hindered-settling correction for concentrated suspensions, giving the clarified-liquid quality inside the flowsheet.