7 Dynamic Simulation of Mechanical Fluid Separation in Solid …
239
Indices
0
Initial position of the particle
i
Compartment
l
Liquid
N
Total number of compartments
S
Solid
sol
Solution
tr
Transport
Abbreviations
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
1 Introduction
Processes dealing with particle formation such as crystallization or precipitation,
syntheses but also the fermentation of biological components usually take place
in an aqueous medium [1, 2]. For better handling and transport as well as further
processing of the mostly particulate valuable material, mechanical fluid separation is
essential as a subsequent separation step after particle generation. Since centrifuges
apply large centrifugal forces, there is a decrease of particle settling time compared
to the settling in the gravity field, which reduces the process time significantly. In the
field of centrifugation, a distinction is made between solid bowl and filter centrifuges.
Solid bowl centrifuges have an impermeable bowl. In filter centrifuges, in contrast,
the bowl is permeable for the filtrate. The particles usually remain on the filter cloth.
At this point, it should be noted that this contribution is limited to the modeling of
solid bowl centrifuges.
The design of solid bowl centrifuges is based on highly simplified models such
as the -theory [3, 4]. The -theory regards the physical behavior of the material
in solid bowl centrifuges as a “black box” and neglects transient phenomena, which
occur due to the spin-up process or as a reaction to load changes. Additionally,
-theory does not consider flow conditions, settling behavior, cake formation and
239
Indices
0
Initial position of the particle
i
Compartment
l
Liquid
N
Total number of compartments
S
Solid
sol
Solution
tr
Transport
Abbreviations
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
1 Introduction
Processes dealing with particle formation such as crystallization or precipitation,
syntheses but also the fermentation of biological components usually take place
in an aqueous medium [1, 2]. For better handling and transport as well as further
processing of the mostly particulate valuable material, mechanical fluid separation is
essential as a subsequent separation step after particle generation. Since centrifuges
apply large centrifugal forces, there is a decrease of particle settling time compared
to the settling in the gravity field, which reduces the process time significantly. In the
field of centrifugation, a distinction is made between solid bowl and filter centrifuges.
Solid bowl centrifuges have an impermeable bowl. In filter centrifuges, in contrast,
the bowl is permeable for the filtrate. The particles usually remain on the filter cloth.
At this point, it should be noted that this contribution is limited to the modeling of
solid bowl centrifuges.
The design of solid bowl centrifuges is based on highly simplified models such
as the -theory [3, 4]. The -theory regards the physical behavior of the material
in solid bowl centrifuges as a “black box” and neglects transient phenomena, which
occur due to the spin-up process or as a reaction to load changes. Additionally,
-theory does not consider flow conditions, settling behavior, cake formation and