258
M. Gleiss and H. Nirschl
Fig. 14 Comparison of the mean solids volume fraction of the underflow dependent on rotational
speed. Left: influence of feed volume fraction for finely dispersed limestone with a mean particle
size of x 50,3 = 3.4 µm. Right: impact of differential speed between screw conveyor and drum for
a limestone-water slurry with a mean particle size of x 50,3 = 1.6 µm [20]
measuring ranges overlap, which indicates that there is only a small influence of
the solids volume fraction. Furthermore, the solids volume fraction of the underflow
increases for higher speeds. Comparing simulation and experiment, it is easy to see
that the calculation underestimates the solids volume fraction of the sediment. At
this point, shear compression can lead to a denser packing of the formed saturated
cakes.
The right-hand side in Fig. 14 shows the influence of differential speed (n) on
the mean solids volume fraction at the underflow for n = 6 rpm and n = 15 rpm.
The influence of the differential speed on the solids volume fraction is significantly
higher for the investigated process compared to the variation of the feed solids volume
fraction. This results in a denser sediment for n = 6 rpm at a lower speed compared
to the simulation setup with n = 15 rpm. In addition, the simulation underestimates
the experimental values for both differential speeds.
5 Dynamic Modeling of Tubular Centrifuges
Another machine type in the class of solid bowl centrifuges are fast-rotating tubular
centrifuges. Due to the slim design, this centrifuge type achieves g-forces up to
C = 100000. This makes the apparatus suitable for the separation of nanoparticles
and proteins from fermentation processes. Another field of application is the defined
classification of nanoparticles. Figure 15 depicts the schematic design of a tubular
centrifuge. A pump delivers the mostly diluted suspension at the bottom axially into
the apparatus. The geometry of the machine forms a liquid pond and a gas core.
The suspension flows in axial direction and leaves the apparatus on the top. The
M. Gleiss and H. Nirschl
Fig. 14 Comparison of the mean solids volume fraction of the underflow dependent on rotational
speed. Left: influence of feed volume fraction for finely dispersed limestone with a mean particle
size of x 50,3 = 3.4 µm. Right: impact of differential speed between screw conveyor and drum for
a limestone-water slurry with a mean particle size of x 50,3 = 1.6 µm [20]
measuring ranges overlap, which indicates that there is only a small influence of
the solids volume fraction. Furthermore, the solids volume fraction of the underflow
increases for higher speeds. Comparing simulation and experiment, it is easy to see
that the calculation underestimates the solids volume fraction of the sediment. At
this point, shear compression can lead to a denser packing of the formed saturated
cakes.
The right-hand side in Fig. 14 shows the influence of differential speed (n) on
the mean solids volume fraction at the underflow for n = 6 rpm and n = 15 rpm.
The influence of the differential speed on the solids volume fraction is significantly
higher for the investigated process compared to the variation of the feed solids volume
fraction. This results in a denser sediment for n = 6 rpm at a lower speed compared
to the simulation setup with n = 15 rpm. In addition, the simulation underestimates
the experimental values for both differential speeds.
5 Dynamic Modeling of Tubular Centrifuges
Another machine type in the class of solid bowl centrifuges are fast-rotating tubular
centrifuges. Due to the slim design, this centrifuge type achieves g-forces up to
C = 100000. This makes the apparatus suitable for the separation of nanoparticles
and proteins from fermentation processes. Another field of application is the defined
classification of nanoparticles. Figure 15 depicts the schematic design of a tubular
centrifuge. A pump delivers the mostly diluted suspension at the bottom axially into
the apparatus. The geometry of the machine forms a liquid pond and a gas core.
The suspension flows in axial direction and leaves the apparatus on the top. The