Fluidized bed coating apparatus

A fluidized bed coating apparatus for coating liquid onto the surfaces of particles comprising:

• a vessel that defines a coating chamber for receiving particles to be coated;
• a processing air inlet for communicating processing air into an underside of said chamber;
• a liquid spray nozzle projecting upwardly toward said chamber from an underside thereof for spraying coating liquid upwardly into said chamber, said spray nozzle having a nozzle body;
• a hollow separator disposed in upstanding relation relative to a discharge end of said spray nozzle into which a coating liquid sprayed from said spray nozzle is directed;
• said processing air inlet being operable for directing a relatively high volume of air flow upwardly into said separator and a lower pressure air flow about an outer perimeter of said separator such that the particles to be coated are directed upwardly into an upbed region of said coating chamber and then downwardly through an outbed region of the coating chamber outwardly of said separator for recirculation into and through said separator;
• said spray nozzle having an ultrasonic driver and a cannular atomizing stem extending from said driver, said stem terminating in a atomizing surface and having a coating liquid flow passage extending along an axis for directing liquid to said atomizing surface such that liquid directed through said liquid flow passage onto said atomizing surface is ultrasonically atomized into a fine liquid particle cloud;
• said nozzle body having a forming air inlet, an air cap mounted at a downstream end of said nozzle body defining an air chamber about said atomizing stem in fluid communication with said forming air inlet, said atomizing stem extending through said air chamber such that said air chamber extends annularly about said atomizing stem, and said air cap and atomizing stem defining a forming air discharge orifice communicating with said air chamber from which an air stream is emitted for propelling forming the finely atomized liquid particle cloud through said separator.