Methods and systems for increasing production of middle distillate hydrocarbons from heavy hydrocarbon feed during fluid catalytic cracking

摘要

A method is provided for increasing production of middle distillate hydrocarbons from conversion of a heavy hydrocarbon feed in a fluid catalytic cracking system having a primary riser and a secondary riser, wherein the method comprises providing regenerated catalyst to the primary riser and operating the primary riser under severe conditions and providing spent catalyst to the secondary riser and operating the secondary riser under moderate conditions.