Abstract
Solid bowl centrifuges are used in a wide range of applications in the process industry. The aim is to separate the individual phases of a liquid/liquid, liquid/solid or liquid/liquid/solid system. The design of solid bowl centrifuges is based on the Σ-theory, which does not describe the separation process with a sufficiently high accuracy. This process results in numbers of experiments with high time and cost expenditure. In addition, Σ-theory only describes the stationary state and therefore do not allow the calculation of start-up processes and load changes. This chapter shows a new real-time capable numerical algorithm, which ensures a high computational efficiency and is therefore suitable for dynamic simulations of the process behavior of solid bowl centrifuges. The introduction deals with the state of the art and the existing problems concerning of the design of solid bowl centrifuges. Subsequently, material functions representing the separation properties in solid bowl centrifuges are expounded. The developed material functions are the basis for the dynamic simulation of the process behavior in solid bowl centrifuges described below. The residence time and flow conditions of the apparatus significantly influence the process behavior for semi-batch and continuous processes. The last two sections present the dynamic modeling of continuously operating decanter and semi-batch tubular centrifuges. Example simulations and comparisons to experiments validate the developed dynamic models and demonstrate the applicability for dynamic simulations.
This is a preview of subscription content, log in via an institution to check access.
Access this chapter
Tax calculation will be finalised at checkout
Purchases are for personal use only
Abbreviations
- A s :
-
Cross section of the sediment [m]
- B sc :
-
Screw pitch [m]
- C :
-
G-force [−]
- D :
-
Flow number [−]
- E(D):
-
Residence time distribution function [−]
- E :
-
Separation efficiency [−]
- F(D):
-
Residence time distribution [−]
- G :
-
Grade efficiency [−]
- h :
-
Hindered settling factor [−]
- L cyl :
-
Length of the cylindrical drum [m]
- L hel :
-
Length of the unrolled screw channel [m]
- \(\dot{m}_{\text{s,i - 1}}\) :
-
Incoming mass flow of solids [kg s−1]
- \(\dot{m}_{\text{s,i}}\) :
-
Outgoing mass flow of solids [kg s−1]
- \(\dot{m}_{\text{s,sep}}\) :
-
Mass flow of separated solids [kg s−1]
- N :
-
Total number of compartments [−]
- n RZ :
-
Exponent Richardson and Zaki [−]
- p 1 :
-
Empirical parameter for solids pressure function [Pa]
- p 2 :
-
Empirical parameter for solids pressure function [−]
- p s :
-
Solids pressure [Pa]
- P :
-
Product loss [−]
- q 3,i :
-
Mass density distribution [m−1]
- Q :
-
Volumetric flow rate [m3 s−1]
- r1, r2:
-
Empirical parameters for hindered settling function [−]
- R d :
-
Radius of the bowl [m]
- R m :
-
Mean radius of the bowl [m]
- R max :
-
Maximum radius of the sediment [m]
- R s :
-
Radius of sediment surface [m]
- R w :
-
Radius of the weir [m]
- Re p :
-
Particle Reynolds number [−]
- Sdyn:
-
Normalized dynamic change [−]
- t :
-
Time [s]
- T :
-
Transport efficiency [−]
- x :
-
Particle diameter [m]
- \(x_{50,3}\) :
-
Mean particle diameter dependent on mass [m]
- \(U\) :
-
Volumetric Filling level [−]
- \(U_{\text{max}}\) :
-
Maximum volumetric filling level [−]
- \(V_{\text{hel}}\) :
-
Volume of the screw channel in the cylindrical part of the decanter centrifuge [m3]
- \(V\) :
-
Volume of a compartment in the sedimentation zone [m3]
- \(V_{\text{sed}}\) :
-
Sediment volume [m3]
- \(\beta\) :
-
Screw angle [rad]
- \(\Delta l\) :
-
Length of a compartment [m]
- \(\Delta n\) :
-
Differential speed between screw and drum [rpm]
- \(\eta\) :
-
Dynamic viscosity [Pa s]
- \(\phi\) :
-
Solids volume fraction [−]
- \(\overline{\phi }_{c}\) :
-
Mean solids volume fraction of the sediment [−]
- \(\rho\) :
-
Density [kg m−3]
- \(\tau\) :
-
Mean residence time [s]
- \(\omega\) :
-
Angular velocity [s−1]
- 0:
-
Initial position of the particle
- i:
-
Compartment
- l:
-
Liquid
- N:
-
Total number of compartments
- S:
-
Solid
- sol:
-
Solution
- tr:
-
Transport
- CFD:
-
Computational fluid dynamics
- CSTR:
-
Continuous stirred tank reactor
- MPC:
-
Model predictive control
- ODE:
-
Ordinary differential equation
- PFR:
-
Plug flow reactor
- PVC:
-
Polyvinylchloride
- RTD:
-
Residence time distribution
- SRF:
-
Single rotating frame
References
Kowalczyk, B., Lagzi, I., Grzybowski, B.A.: Nanoseparations: strategies for size and/or shape-selective purification of nanoparticles. Curr. Opin. Colloid Interf. Sci. 16, 135–148 (2011). https://doi.org/10.1016/j.cocis.2011.01.004
Kanarska, Y., Lomov, I., Antoun, T.: Mesoscale simulations of particulate flows with parallel distributed Lagrange multiplier technique. Comput. Fluids 48, 16–29 (2011). https://doi.org/10.1016/j.compfluid.2011.03.010
Ambler, C.M.: The evaluation of centrifuge performance. Chem. Eng. Prog. 48, 150–158 (1952)
Ambler, C.M.: The theory of scaling up laboratory data for the sedimentation type centrifuge. J. Microb. Biochem. Technol. 1, 185–205 (1959)
Leung, W.W.-F.: Industrial Centrifugation Technology. McGraw-Hill, New York (1998)
Gleiss, M., Hammerich, S., Kespe, M., Nirschl, H.: Application of the dynamic flow sheet simulation concept to the solid-liquid separation: separation of stabilized slurries in continuous centrifuges. Chem. Eng. Sci. 163, 167–178 (2017)
Konrath, M., Brenner, A., Dillner, E., Nirschl, H.: Centrifugal classification of ultrafine particles: Influence of suspension properties and operating parameters on classification sharpness. Sep. Purif. Technol. 156, 61–70 (2015)
Romanni Fernández, X., Nirschl, H.: A numerical study of the impact of radial baffles in solid bowl centrifuges using computational fluid dynamics. Phys. Sep. Sci. Eng. (2010)
Romaní Fernández, X., Nirschl, H., Fernández, X.R., Nirschl, H.: Simulation of particles and sediment behaviour in centrifugal field by coupling CFD and DEM. Chem. Eng. Sci. 94, 7–19 (2013). https://doi.org/10.1016/j.ces.2013.02.039
Hammerich, S., Gleiß, M., Nirschl, H.: Modeling and simulation of solid-bowl centrifuges as an aspect of the advancing digitization in solid-liquid separation. Chemie Ing. Tech. 91, 215–227 (2019)
Hammerich, S., Gleiß, M., Kespe, M., Nirschl, H.: An efficient numerical approach for transient simulation of multiphase flow behavior in centrifuges. Chem. Eng. Technol. 41, 44–50 (2018)
Stahl, W.: Fest-Flüssig-Trennung Band II: Industrie-Zentrifugen, Maschinen-und Verfahenstechnik. DRM Press, CH-Männedorf (2004)
Skinner, S.J., Studer, L.J., Dixon, D.R., Hillis, P., Rees, C.A., Wall, R.C., et al.: Quantification of wastewater sludge dewatering. Water Res. 82, 2–13 (2015). https://doi.org/10.1016/j.watres.2015.04.045
Lerche, D.: Dispersion stability and particle characterization by sedimentation kinetics in a centrifugal Field. J. Dispers. Sci. Technol. 23, 37–41 (2007)
Detloff, T., Sobisch, T., Lerche, D.: Particle size distribution by space or time dependent extinction profiles obtained by analytical centrifugation. Powder Technol. 174, 50–55 (2007)
Anlauf, H.: Recent developments in centrifuge technology. Sep. Purif. Technol. 58, 242–246 (2007). https://doi.org/10.1016/j.seppur.2007.05.012
Beiser, M., Bickert, G., Scharfer, P.: Comparison of sedimentation behavior and structure analysis with regard to destabilization processes in suspensions. Chem. Eng. Technol. 27, 1084–1088 (2004). https://doi.org/10.1002/ceat.200403252
Richardson, J.F., Zaki, W.N.: Sedimentation and fluidisation: Part I. Chem. Eng. Res. Des. 75, 82–100 (1997)
Michaels, A., Bolger, J.: Settling rates and sediment volumes of flocculated kaolin suspensions. Ind. Eng. Chem. Fundam. 1, 24–33 (1962)
Gleiß, M.: Dynamische Simulation der Mechanischen Flüssigkeitsabtrennung in Vollmantelzentrifugen, KIT Scientific Publishing (2018)
Stickland, A.D.: Solid-liquid separation in the water and wastewater industries. University of Melbourne (2005)
Spelter, L.E., Nirschl, H., Stickland, A.D., Scales, P.J.: Pseudo two-dimensional modeling of sediment build-up in centrifuges: a compartment approach using compressional rheology. AIChE J. 59, 3843–3855 (2013)
Usher, S.P., Studer, L.J., Wall, R.C., Scales, P.J.: Characterisation of dewaterability from equilibrium and transient centrifugation test data. Chem. Eng. Sci. 93, 277–291 (2013)
Green, M.D., Eberl, M., Landman, K.A.: Compressive yield stress of flocculated suspensions: determination via experiment. AIChE J. 42, 2308–2318 (1996)
Mladenchev, T., Tomas, J.: Modellierung der Filtrations- und Konsoldierungsdynamik von geflockten und nicht geflockten feindispersen Kalksteinsuspensionen. Chemie Ing. Tech. 76, 1814–1818 (2004)
Erk, B., Luda, A.: Beeinflussung der Schlammkompression in Vollmantelzentrifugen. Chemie Ing. Tech. 75, 1250–1254 (2003). https://doi.org/10.1002/cite.200303260
Le Moullec, Y., Potier, O., Gentric, C., Leclerc, J.: Flow field and residence time distribution simulation of a cross-flow gas-liquid wastewater treatment reactor using CFD. Chem. Eng. Sci. 63, 2436–2449 (2008)
Gleiss, M., Nirschl, H.: Modeling separation processes in decanter centrifuges by considering the sediment build-up. Chem. Eng. Technol. 38, 1873–1882 (2015)
Stahl, S., Spelter, L.E., Nirschl, H.: Investigations on the separation efficiency of tubular bowl centrifuges. Chem. Eng. Technol. 31, 1577–1583 (2008)
Author information
Authors and Affiliations
Corresponding author
Editor information
Editors and Affiliations
Rights and permissions
Copyright information
© 2020 Springer Nature Switzerland AG
About this chapter
Cite this chapter
Gleiss, M., Nirschl, H. (2020). Dynamic Simulation of Mechanical Fluid Separation in Solid Bowl Centrifuges. In: Heinrich, S. (eds) Dynamic Flowsheet Simulation of Solids Processes. Springer, Cham. https://doi.org/10.1007/978-3-030-45168-4_7
Download citation
DOI: https://doi.org/10.1007/978-3-030-45168-4_7
Published:
Publisher Name: Springer, Cham
Print ISBN: 978-3-030-45167-7
Online ISBN: 978-3-030-45168-4
eBook Packages: Chemistry and Materials ScienceChemistry and Material Science (R0)