Staged burning of retorted carbon-containing solids

Claim 1

A process for burning pyrolyzed solids containing a carbonaceous residue to provide heat for the pyrolysis of a particulate carbon-containing solid, wherein said pyrolyzed solids contain both a fine fraction and a coarse fraction and at least part of said fine fraction is contained in a separate feedstream from the coarse fraction of the pyrolyzed solids, said process comprising: (a) burning at least part of the carbonaceous residue in the fine fraction contained in said separate feedstreem in a dilute phase preburner by entraining the fine fraction in a first entraining gas stream containing oxygen and having a velocity greater than the terminal velocity of the particles in the fine fraction; (b) mixing the entrained, partially burned fine fraction from the preburner with the remainder of the pyrolyzed solids in a second entraining gas stream having a velocity greater than the terminal velocity of the coarse and fine fractions; and (c) burning the unburned carbonaceous residue in the fine and coarse fractions in a second dilute phase combustion zone through which the second entraining gas and entrained solids are directed, said second dilute phase combustion zone containing sufficient oxygen to burn all of the unburned carbonaceous residue in the fine and coarse fractions.