Process for conversion of gas oil to ethylene and needle coke

摘要

A process for the conversion of gas oil to a naphtha pyrolysis feedstock and needle coke comprising thermally cracking the gas oil to produce a product comprising cracked naphtha and aromatic tar oil, delay coking said aromatic tar oil to produce needle coke and coker naphtha, and hydrotreating said cracked naphtha and said coker naphtha at a temperature at least 50 DEG F. (28 DEG C.) lower than the temperature in the thermal cracking and coking zones to avoid hydrocarcking reactions and to produce a hydrogenated naphtha containing at least 10 volume percent of cycloparaffins. Said hydrogenated naphtha is thereupon passed through a pyrolysis zone without added molecular hydrogen and without a catalyst operated at a temperature between 1,300 and 2,300 DEG F. (704 and 1,260 DEG C.) and a residence between 0.05 and 2 seconds to produce a product containing ethylene. The ethylene yield can be increased by adding a sulfur compound to the hydrogenated naphtha stream flowing to the pyrolysis zone.