Patent ID: 8262903

Claim:
A method for thermal cracking processing of heavy petroleum oil, comprising: blowing superheated steam of 400 to 700° C., from a bottom portion of a reaction vessel, into the heavy petroleum oil having been heated to 450° C. or higher in a heating furnace and thereafter introduced into the reaction vessel of which at least a shell has a cylindrical shape; bringing the superheated steam into direct contact with the heavy petroleum oil to be thermally cracked into an oil fraction and a pitch; and discharging the oil fraction successively from a top of the reaction vessel together with the superheated steam and removing the pitch from the reaction vessel collectively after the completion of the thermal cracking, wherein: in blowing the superheated steam from the bottom portion of the reaction vessel, the blowing is carried out through one or two or more blowing orifices which are provided to the bottom portion of the reaction vessel and opened to the inside of the reaction vessel so that the superheated steam generates a rotational flow around the central axis of the shell inside of the reaction vessel; and the blowing of the superheated steam from the blowing orifices is directed so as to be parallel or upward against a plane which is perpendicular to the axis of the shell of the reaction vessel and includes the blowing orifices, and to have a facing angle θ between the blowing and the normal line on the plane to the outer wall of the reaction vessel of 20° or more and 60° or less.