Abstract: A sludge incinerator for use in the flash evaporation of water contained in high moisture sludges comprises a primary chamber, with longitudinally spaced inlet tubes to introduce the sludge and compressed air therein in an atomized spray, and primary burners intermediate the inlet tubes, to heat and burn the sludge, thus separating it into dry solids and water vapor. A screw conveyor removes the dry solids from the primary chamber. An afterburner, including secondary burners, a secondary air supply, and a mixing chamber to mix the secondary air with the primary combustion products, provides further oxidation to achieve substantially complete combustion of the combustibles content of the sludge and fuel. A vertical stack exhausts these combustibles and vapors from the mixing chamber.