The invention provides a system for continuous processing of heavy fuel oil from recycling waste oil and the processing residues of crude oil into useful products comprising means for feeding waste oil; at least one hot-gas filter, at least one condenser, at least one rotating kiln comprising an outer stationary jacket which forms a heating channel, and an inner rotating reactor, and means for removing solid coke from the rotating reactor; wherein the at least one hot gas filter is configured to separate a naphtha/gasoil fraction after the processing of the heavy fuel oil from a soft coke fraction; and wherein the rotating reactor is configured to recover a solid coke fraction comprising high contaminant content. The invention further relates to a process for continuous processing of heavy fuel oil from recycling waste oil and the processing residues of crude oil into useful products, preferably with the system of the invention. Moreover, the invention relates to use of the products and waste products produced with the process and system of the invention.