Wet Granulation Small Scale Experiments. Quantitative Engineering Approaches. How do we design experiments and scale ?. What do we know?. Implications. Nothing except parameters we can vary. Statistical Experimental Design . Lots of experiments at all scales.
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How do we design experiments and scale ?
What do we know?
Nothing except parameters we can vary
Statistical Experimental Design
Lots of experiments at all scales
Fully predictive model
Granulation Rate Processes:
Nucleation regime dimensionless numbers:
Dimensionless spray flux (a)
Dimensionless drop penetration time (p)
Hapgood, Litster & Smith, AIChE J,49, 350-361, 2003
Growth regime dimensionless numbers:
Maximum liquid saturation (Smax)
Stokes deformation number (Stdef)
w : mass ratio of liquid to solid
s: density of solid particles
l: liquid density
min: minimum porosity the formulation reaches
g: granule density
Uc: collision velocity
Yd: dynamic yield stress
Iveson et al., Powder Technol., 117, 83-87, 2001
(HPC EXF) dry mixture (15:1 w/w %)
d50: 169 5 µm
Particle size distribution of Gabapentin
Wet granule dynamic yield stress
Dry gabapentin + HPC – 250 rpm
Powder surface velocity at 35 % fill ratio:
Powder flow direction
Smax values combined with Stdefvalues give the amount of liquid required for granulation as well as the failing conditions.