Abstract: A gas distribution system employing an array of parallel gas inlet pipes and a pair of transverse gas inlet pipes located below the first group of pipes to fluidize a particulate bed in a reaction vessel and to remove non-fluidizable particles that may be introduced into or form in the bed.

Abstract: A method of oxidizing feed materials using a multiple hearth furnace comprises the steps of introducing the feed materials to be oxidized on at least the uppermost hearth, introducing fuel/air mixtures in the uppermost hearth to dry and ignite the feed materials, introducing air on at least one hearth to support combustion of the feed materials, allowing the feed materials to move downwardly from hearth to hearth and thereafter to exit the bottom of the furnace, and causing the combustion products formed by oxidation of the fuel and feed materials to be drawn down through the furnace and exhausted from a lower hearth.