Patent ID: 7267233

Claim:
A classifying device suitable for classifying particulates entrained in a flowing gas stream, comprising: a) a flow stream inlet and an upwardly extending flow stream outlet, said flow stream inlet and flow stream outlet angled with respect to each other such that the direction of flow of said flowing gas stream changes between said flow stream inlet and said flow stream outlet, said device having a volume between said flow stream inlet and said flow stream outlet through which said flowing gas stream flows; b) a target positioned in said volume such that particles to be removed and entrained in said flowing gas stream contract said target and fall downward; and c) a downwardly extending fluidized particle trap communicating with said volume, said fluidized particle trap having at least one fluidizing gas inlet, whereby particles of greater mass and/or density than the mass and/or density of particles targeted to remain in the flowing gas stream accumulate in said fluidized trap, wherein a restrictive ring is fixed to the inside of said fluidized trap, said restrictive ring being a ring of conical section having a height, and said fluidizing gas enters said trap at a location in the trap walls within the height of said ring of conical section.