Abstract: Device making it possible to effect the injection of sludge originating, in particular, from sewage-purification stations, into the combustion chamber of an incinerator, in particular of a household-refuse incinerator, characterized in that it comprises at least one injector (10) of small diameter, traversing the thermal-projection means of the combustion chamber and fed, at a constant rate for all of the injectors, via a distribution chamber (12), each injector consisting of a tube (18) having a cylindrical shape and comprising a conical nozzle (20), on the combustion chamber side, with the large diameter situated on the side of the outlet of the sludge from the injector, and in that each injector is thermally regulated in order to obtain a linear temperature gradient along the whole length of the injector, causing the formation in the injector, as the injection progresses, of a cylindrical element of sludge having a predetermined diameter and a surface crust in the zone close to the combustion chamber.