PURPOSE: To increase the amounts of naphtha, kerosine and gas oil fractions and to reduce sulfur content in light oil and pitch, by a method wherein in a two-stage thermal treating method of heavy oil, part of thermally cracked oil obtained is hydrogenated, the resulting hydrogenated product is mixed with the raw heavy oil and the mixt. is subjected to the thermal treatment.
CONSTITUTION: In a thermal cracking treating method of heavy oil comprising carrying out a first-stage thermal treatment of the heavy oil at a temp. of 450W 550°C and carrying out a second-stage thermal treatment at a temp. of 350W 450°C to obtain thermally cracked oil and pitch from the heavy oil; part of the resulting thermally cracked oil is hydrogenated and the resulting hydrogenated product of the thermally cracked oil is mixed with the heavy oil to be treated in the first stage to carry out said first-stage thermal treatment. The hydrogenated thermally cracked oil to be recycled is pref. a fraction having an H/C atomic ratio of not less than 1.65 and a boiling point of 250W550°C in the thermally cracked oil before desulfurization. The hydrogenated oil is used in an amount of pref. 5W45wt% based on the weight of the heavy oil introduced into the first-stage thermal treatment.
SUGAWARA SHIYUUICHI
KONNO TSUTOMU
