Abstract: A vertically standing, slender, cylindrical flow container with an upper intake connection for crushed raw sludge already heated to a pasteurization temperature and a lower outlet connection for pasteurized sludge. A slowly rotating guide member is incorporated into the container coaxially with the longitudinal axis of the latter and is driven by an electric motor via a reduction gear. The tube-like guide member core is provided with a plurality of continuous, helically-wound blades which extend from top to bottom and which, with respect to the direction of rotation of the guide member, form front and rear helical deflectors for the sludge. The helically wound blades also subdivide the circular cross-section of the passage of the container into a plurality of helically-wound individual channels.

Abstract: A method for drying sludge which may contain combustible vapors in a manner to positively prevent fires and explosions within the sludge dryer and the associated sludge-drying piping. The method provides for a substantial reduction of the oxygen content of the sludge-drying vapors by deviating a part of the sludge-drying vapor stream from the principal vapor circuit and passing it as secondary combustion air into the combustion chamber which generates hot gases for drying the sludge. Furthermore, a portion of the hot effluents from the combustion chamber is deviated from the sludge-drying circuit and is used to heat the sludge-drying vapors whereafter it is vented to the atmosphere. In a variant of the invention, an acid scrubber is provided to remove hydrochloric acid. A number of embodiments is presented.