Process for thermally cracking heavy hydrocarbon oil

Abstract

A continuous process for thermally cracking a heavy hydrocarbon oil, including heat-treating the heavy hydrocarbon oil in a first thermal cracking zone for obtaining a first cracked product, and introducing the first cracked product into a second thermal cracking zone where it is thermally cracked by direct contact with a gaseous heat transfer medium to form distillable cracked components and a mesophase-containing pitch. The liquid phase in the second thermal cracking zone, including the mesophase-containing pitch, is withdrawn therefrom and separated into a mesophase-rich pitch and a matrix pitch having a low concentration of mesophase. The matrix pitch is recycled to the second thermal cracking zone. The distillable cracked components are stripped from the liquid phase in the second thermal cracking zone with the heat transfer medium, and the resulting gas phase is discharged overhead therefrom and then separated into a light fraction and a heavy fraction. The heavy fraction is fed to a third thermal cracking zone to obtain light oil components and an aromatic tar. The aromatic tar is recycled to the second thermal cracking zone.