Abstract: This invention is a device for pyrolyzing waste materials comprising a low - temperature carbonizing reactor. The reactor includes a longitudinally extending tubular vessel adapted to be loaded with waste materials to be pyrolyzed and a flue gas duct which surrounds a shell of the carbonizing reactor, which defines an annular space which concentrically surrounds the tubular vessel, and which is adapted to have hot flue gases passed therethrough for the purpose of heating the shell of the reactor. The flue gas duct contains a baffle for maintaining turbulent flow about the reactor and for uniformly distributing the flue gases about the periphery of the tubular vessel. The baffle comprises a plurality of heat conducting elements which are disposed in planes which contain the longitudinal axis of the annular space and a plurality being disposed in planes extending at right angles to the longitudinal axis of the annular space.