The small-scale fluid bed was a modified GEA Aeromatic-
Fielder Strea-1 top-spray fluidised bed with a stainless steel fluidising chamber with a bottom plate diameter of 10.0 cm
allowing a particle bed load of 500 g to be fluidised. A picture of
the modified Strea-1 set-up can be seen in Fig. 3. Modification
to the original vessel design made it possible to insert a digital
thermometer into the fluidisation chamber wall thereby
enabling measurement of the bed temperature between the
bottom air distributor plate and the nozzle outlet. In addition, a
humidity measurement apparatus (Testo 645 Thermohygrometer
with TopSafe probe measuring humidity highly accurately
with a sensitivity of ±1 rH% in the range of 0.1–99.9 rH%) was
inserted above the nozzle allowing the relative humidity in the
fluidisation chamber to be measured. The vertical position of
15 cm from the nozzle outlet and a horizontal probe depth of
12 cm were carefully chosen in order not to let the humidity
measurements be directly affected by the nozzle outlet. Custommade
reusable stainless steel filters were inserted in the top of
the fluidisation chamber in order to prevent particles and spraydried
coating droplets from being exhausted. The back-flush
option in the Strea-1 set-up was switched on allowing the filters
to be flushed every 60 s.