Processing of dispersions containing fine particles or biological products in tubular bowl centrifuges

Computational Fluid Dynamics (CFD) and Discrete Element Method (DEM) Applied to Centrifuges

“…Today, most researchers who work with solid bowl centrifuges support the boundary layer theory. Recent studies by the authors have confirmed the validity of this theory for industrial solid bowl and tubular bowl centrifuges (Romani Fernandez & Nirschl, 2009;Spelter et al, 2010). Nevertheless it is important to pay attention to the acceleration geometry of the centrifuge and the influence of the settled particles on the flow pattern.…”

Pseudo two‐dimensional modeling of sediment build‐up in centrifuges: A compartment approach using compressional rheology

“…The particle Reynolds number has been calculated in a previous work showing that the Stokesian approach is applicable to the particle-systems and operating parameters used here. 4 With increasing solids concentration, the settling velocity decreases due to the reduced free cross-sectional area. Whilst dilute suspensions with unhindered settling are used here, hindered settling can be implemented if necessary.…”

“…Their experimental observations and further investigations by the authors determined a conical shape of the sediment rather than a plug-shaped one. 4,5 The differences between the modeled and observed sediment build-up are caused by the varying settling path of particles with different sizes and different initial radial positions in the flow. The sediment angle decreases with lower separation efficiency, because the particles settle along the entire length of the rotor.…”

“…The sediment angle decreases with lower separation efficiency, because the particles settle along the entire length of the rotor. 4 If the cut size of the centrifuge exceeds the mean particle size of the dispersed solids, the sediment angle tends to be less than 10 . These effects are not captured by the previously published model by Stahl et al and the error of the existing model increases significantly due to the disagreement between assumed and observed sediment profile.…”

“…The sediment build-up has a significant influence on the process outcome during the semibatch, because the residence time is reduced by the accumulating solids. 4 It is important to capture the real sediment build-up, because the flow pattern is influenced by the sediment growth. Depending on whether the sediment is plug shaped or homogeneously distributed over the rotor, the interaction between settled solids and flow will be different.…”