Combustion of pyrolyzed carbon containing solids in staged turbulent bed

Claim 1

A process for producing heat from particulate pyrolyzed carbon containing solids containing a mixture of various size particles which comprises the steps of: (a) introducing the pyrolyzed carbon containing solids into the upper portion of a generally vertically oriented dense phase combustion zone through which the solids pass downward as a continuous moving bed of material, said dense phase combustion zone being characterized by the presence of a plurality of dispersing elements so disposed as to limit gross vertical backmixing of the solids passing downward therethrough; (b) burning the carbonaceous material remaining on the pyrolyzed solids as they move downward through the dense phase combustion zone by introducing an oxidizing gas into the bottom of the dense phase combustion zone and withdrawing combustion gases from the upper portion of the zone; (c) passing the flow of oxidizing gas in a generally countercurrent manner to the downward moving solids at a velocity sufficient to entrain a fine fraction of ash particles below a preselected size, sufficient to fluidize an intermediate size fraction, and insufficient to entrain or fluidize a coarse fraction, whereby the fine fraction is carried upward with the flow of gas as entrained particles and the intermediate and coarse fractions pass downward; and (d) withdrawing the entrained fine fraction with the gas leaving the upper portion of the dense phase combustion zone and separately withdrawing the intermediate and coarse fractions from the lower part of the dense phase combustion zone.