Gasoline octane enhancement in fluid catalytic cracking process with split feed injection to riser reactor

摘要

A fluid catalytic cracking unit equipped with multiple feed injection points along the length of the riser is operated such that portions of the same fresh feed are charged to different feed injection points. Preferably, the hydrocarbon fresh feed can be split into two or more non-distinct fractions, with one fraction charged to the bottom injection point along the length of the riser reactor, and the remaining fractions charged to injection points progressively higher up along the length of the riser reactor. Unconverted slurry oil boiling above 650°F can be recycled to one or more of the various injection points along the length of the riser. Steam in excess of levels typically employed for dispersion is used at the bottom of the riser to help lift the regenerated catalyst. Other inert gases can be used in place of, or in conjunction with, steam to accomplish lifting of the catalyst in the riser.