Split plenum arrangement for an apparatus for coating tablets

A fluidized bed apparatus for applying a coating liquid onto the surface of particles includes a vertically disposed cylindrical product container having a peripheral wall, at least one cylindrical partition defining a centrally located up bed region and a peripherally located down bed region. The product container further includes an upper end connected to an expansion chamber and a lower end including an orifice plate having a plurality of openings for passage of fluidized air or gas. The fluidized apparatus further includes a central first plenum located below the orifice plate and being aligned with the up-bed and the partition, the first plenum being sized and shaped to direct gas upwardly through the orifice plate and into the up-bed; and a second plenum located below the orifice plate positioned around the first plenum for directing gas upwardly through the orifice plate and into contact with particles located on the orifice plate.