Standard Strea-1 reusable nylon filters were inserted at the top of the fluidisation chamber in order to prevent particles and spray-dried 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 fifth second.
The applied spray nozzle was a two-fluid nozzle with an outlet diameter of 0.8 mm. An integrated heating jacket connected to a thermostated external water bath at 80 °C heated the nozzle itself. In the applied set-up, the nozzle was placed 25 cm above the air distribution plate. The compressed atomising air was in addition led through an external heating cartridge at 80 °C before reaching the nozzle. This option was necessary in order to prevent clogging of the nozzle caused by crystallisation of the coating solution due to temperature drop inside the nozzle. The coating liquid feed was led from the external heated reservoir at 80 °C to the nozzle through an adjustable electrical peristaltic tube pump. A sketch of the modified Strea-1 set-up can be seen in Fig. 4 and the general operating process and formulation conditions can be seen in Table 1.