Download SCALE UP OF HIGH SHEAR WET GRANULATION PROCESS

SCALE UP OF HIGH SHEAR WET GRANULATION PROCESS
BOUHAOUCHE 1 amina, KACI 1 nassima, GUELLOUR 2 amina, DAOUD 1 kamel
1 University of Science and Technology Houari Boumediene.
Faculty of Mechanical Engineering and Process Engineering
. BP 32 El Alia 16111 Bab Ezzouar. Algiers
2 BIOPHARM Pharmaceutical Laboratories. Development Laboratory.
Industrial Zone Oued Smar. Algiers
Email: [email protected]
Abstract
Wet granulation is the agglomeration process of a powder mixture obtained by using a binder
solution. This process is widely used in pharmaceutical industry to increase the flow rate and
flow uniformity of mixture before tableting.The high shear mixers are widely used for wet
granulation process, because it permits to obtain uniformity in the size distribution of the
granules. The granulation process is sensitive to change in powder characteristics and process
factors. During the developement phase, manufacturing is carried out using laboratory or pilot
size equipement, subsequently, the process has to be transfered to large production scale. For
the high shear mixer containing a binder solution with density  (kg/m 3 ) and viscosity
 (Pa.s), driven by an impeller of diameter D (m), rotating at a speed of N (rev/s), three
dimensionless numbers can be defined:
1-The power number, which relates the drag force acting on a unit area of the impeller area
and the inertial stress, is given by:
pg
(1)
Np=
N 3 D 5
Where P is the power of the impeller motor (W) and g is the gravitational constant (m.s 2 ).
2- The Reynolds number which relates the inertial force to the viscous force and is given by :
D 2 N
N Re =
(2)

3-The Froude number which relates the inertial stress to the gravitational force per unit area
acting on the material and is given by :
N 2D
N Fr =
(3)
g
In this work, we experiment the wet granulation of a pharmaceutical drug in a small mixer
(25 l) and found the relationship between the three dimensionless numbers. We deduced the
necessity to modify the equation by introducing the diameter of the impeller and the height of
the product in the tank.
We use this correlation to predict the size distribution of the granules in the big mixer (600 l)
and we note that this equation is agree with the experimental values.