Abstract: A plant for continuously retorting oil products contained in shales and sands comprising a substantially horizontal retort furnace into which said shales and sands are introduced by means of hoppers and metering devices and placed on metal conveyors moving in counter-current to gases, means being provided for placing said shales and sands onto said conveyors with a suitable thickness and for stirring the shales and sands. One or more combustion chambers are arranged outside said retort furnace for producing hot gases, and one or more input zones are located along the retort furnace for admitting hot gases into the retort furnace, causing the hot gases to mix with circulating gases which have been preheated by removing sensible heat from the exhausted shale and sand material. A direct contact condenser at the furnace head utilizes cold fluid to condense distilled oil products, and a decantation tank is arranged beneath said condenser for freeing the process gases from the dust.

Abstract: A process for making modular element for heat exchangers with thermoplastic tubes consisting of a plurality of tubes connected to one another by spacers located at intervals allowing the mutual tape-like positioning of the tubes. Also a process for making a tube nest consisting of a plurality of such modular elements.