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chamber chamber
Discharging Port in product Port in product Port in product Port in product
chamber chamber chamber chamber
JOURNAL OF PHARMACEUTICAL SCIENCES, VOL. 98, NO. 11, NOVEMBER 2009 DOI 10.1002/jps
FLUIDIZATION TECHNOLOGIES 3949
gap air velocity and bulk volume of the powder into the outer chamber via the perforations on the
mass. Eqs. (1) and (2) are the modifications of the metal ring. The single chamber type design is
Froude number equation as reported by Horsthuis manufactured by Glatt as Glatt Rotor Granulator
et al.106 for rotational speed (V) and centrifugal (Glatt GMBH, Germany) and by Freund (Freund
force ( Fc), respectively. The centrifugal force is Industrial Co. Ltd., Japan) as a Spir-a-flow
directly proportional to the weight (W) of the granulator. The double-chamber design was
material and square of the rotational speed and patented and manufactured by Aeromatic-Fielder
inversely related to the plate radius (R) AG (Aeromatic-Fielder AG, now Niro Pharma
Systems, Switzerland).114 While patent US
p R
Patent 3,671,296 is for the rotor technology
V ¼ Fc (30)
W
equipment and coating of the granular material,
subsequent patents (US 4,034,126 and US
WV2
4,542,043) are for the coating of spherical
Fc ¼ (31)
R
granules. Fluid Bed Multi-ProcessorTM (GEA
Pharma systems) enables attachment of modules
There are three better known manufacturers of
to the central fluid bed for specific functions like
rotary Processors namely GEA-Aeromatic, Glatt
blending, granulating, drying, pelletizing, and
Air Technique and Vector/Freund Corporation.107
coating. The equipment is versatile in function.
The basic design of these units contain distinctive
It has both options of spray dryer granulator and
features. The prototype equipment was initially
top spray granulator systems.
first developed in the 1970s108 and progress in
modifications to the basic design resulted in the
rotor granulator (Glatt), roto-processor (Aero-
matic), spir-a-flow (Freund) and centrifugal gran- Rotating Plate Design and Its Significance
ulator (Freund). In few equipments, drying may
In the rotary processor the rotating plate plays a
be a rate limiting step in centrifugal granulators
very significant role in material movement that
that are not enclosed in a fluidized bed system.109
relies mainly on the forces set up by the rotating
In such cases, the air velocity can be controlled by
plate to bring about liquid distribution and mixing
the width of the gap between the rotating plate
during the liquid addition stage in spherodization
and chamber wall and the height of the rotating
process. Different plate modifications can be
plate may be adjusted in some models. Several
employed depending on the process and use. For
processing techniques such as powder layering,
example, when the rotary processor is used for
solution layering, and wet spheronization, as well
powder layering or coating with core spheroids,
as coating can be exploited. Wet spheronization
rotating plates with smooth surfaces or comple-
in rotary processor consists of three stages viz.
tely smooth plates instead of plates with pro-
addition of liquid, tumbling of material, and
tuberances are employed since the base material
drying.110 Dense spheroids of narrow size dis-
used (like nonpareil seeds or core spheroids) have
tributions can be prepared by rotary spheroniza-
good inherent flow properties. Although the
tion.111 113
smooth plate avoids material adhesion it does
not supply sufficient shear for effective spheroni-
zation.115 In conventional extrusion-spheroniza-
Single and Double Chamber Systems
tion the rotating plate surface consists of grooves
Two basic chamber designs namely the single that aid break up of rod-shaped extrudates and to
chamber and double chamber systems have been reshape the short rods into spheres.116 The typical
employed in rotary processors. In the single cross-hatch pattern (Fig. 9A), where grooves
chamber type, the drying and coating takes place vertically intersect each other is the most
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