shows a schematic diagram of a small scale batch top- spray fluidized bed coating apparatus. This system consists of two main parts, fluidized bed unit and spraying unit. In the fluid- ized bed unit, it consists of a stainless steel coating chamber with an inner diameter of 0.27 m and height of 1 m. A high-pressure blower (Venz, model HB 2.2, Thailand) was used to supply the flu- idizing air. The velocity of inlet air was adjusted by butterfly valve and measured by the hot wire anemometer (Testo, model 445, Len- zkirch, Germany). The inlet air temperature was heated by electric heater and its temperature was controlled by proportional- integral–differential (PID) controller (Linking, model LT400, Taiwan). The heated air enters the bed through the air distributor plate that was made from a stainless steel perforated plate. The perforated plate had a hole diameter of 1.5 mm. The exhaust air flowed through the cyclone separator in order to remove the dust and then the clean air about 80% of total exhaust air was reused again. In the part of spraying unit, the diaphragm dosing pump (Grundfos, model Alldos DMS 12–3, France) was used to supply the coating solution to the internal mixing two-fluid nozzle