Treatment of solids in fluidized bed burner

A process for thermal treatment of solid particles in a fluidized bed, said solid particles characterized by thermal treatment forming a lighter weight fraction and a heavier weight fraction, relative to the total contents of the bed, said process comprising:

• feeding solid particles to a fluidized bed of solid particles, said fluidized bed supported on a bed support having at least one region of opposing downwardly sloping portions converging in thier lower portions into an opening of a density/size particle classification heavier particle discharge conduit, said heavier particle discharge conduit having a necked region;
• maintaining said fluidized bed of solid particles in fluidized condition by pressurized fluidizing gas entering said bed through a plurality of nozzle means in said bed support and pressurized solids discharge gas entering through said heavier particle discharge conduit controlling heavier particle passage therethrough;
• maintaining a discrete fluid fueled flame in said fluidzied bed in close proximity to and above said opening of said heavier particle discharge conduit by feeding fuel and oxidant through a burner extending upwardly through the central portion of said heavier particle discharge conduit and having an outlet above said opening forming a higher temperature zone in and surrounding said flame, said higher temperature one at least about 100.degree. F. higher than the remainder bed temperature;
• circulating said solid particles in said fluidized bed through said higher temperature zone heating said particles to form said heavier weight particle fraction;
• maintaining flow velocity of said solids discharge gas upwardly through an annular passage between said burner and said necked region of said heavier particle discharge conduit sufficiently high to permit downward passage of said heavier wieght particles for discharge while restraining from downward passage substantially all said ligher weight fraction and recirculating said lighter weight fraction through said higher temperature zone, and withdrawing said heavier weight particles through said heavier particle discharge conduit;
• and
• withdrawing said lighter weight fraction from the upper region of said bed.