In the effort to fix as many parameters as possible across
scale, the three different fluid bed set-ups were carefully chosen to be as similar as possible. All three were top-sprayed fluid
beds each having a single two-fluid nozzle. In all three cases an
outlet nozzle liquid orifice diameter of 1.2 mm was used.
Likewise, the coating liquid feed was in each case led from an
external heated reservoir at a constant temperature of 60 °C to
the nozzle through an adjustable peristaltic tube pump. A sketch
of the general set-up in each of the three fluid bed systems may
be seen from Fig. 1 and the physical dimensions of the three
fluid bed scales may be seen from Fig. 2. For all three fluid beds
the fluidisation air inlet temperature and fluidisation velocity as
well as the nozzle pressure was controlled independently via the
fluid bed control interface. All other parameters had to be
adjusted accordingly