Process and apparatus for upgrading FCC product with additional reactor with catalyst recycle

Abstract

A process and apparatus is disclosed for contacting feed with mixed catalyst in a secondary reactor that is incorporated into an FCC reactor. The mixed catalyst used in the secondary reactor is regenerated catalyst from a regenerator that regenerates spent catalyst from an FCC reactor that is mixed with spent catalyst from either the FCC reactor or the secondary reactor. The mixing of spent and regenerated catalyst reduces the catalyst temperature and tempers catalyst activity to inhibit both thermal and catalytic cracking reactions.

Description

BACKGROUND OF THE INVENTION This invention relates generally to processes for the fluidized catalytic cracking (FCC) of heavy hydrocarbon streams. More specifically, this invention relates to processes for upgrading catalytically cracked hydrocarbon feeds in a discrete reactor vessel. DESCRIPTION OF THE PRIOR ART The FCC process is carried out by contacting the starting material whether it be vacuum gas oil, reduced crude, or another source of relatively high boiling hydrocarbons with a catalyst made up of finely divided or particulate solid material. The catalyst is transported in a fluid-like manner by passing gas or vapor through it at sufficient velocity to produce a desired regime of fluid transport. Contact of the oil with the fluidized material catalyzes the cracking reaction. The cracking reaction deposits coke on the catalyst. Catalyst exiting the reaction zone is spoken of as being “spent”, i.e., partially deactivated by the deposition of coke upon the catalyst. Coke is ...

AI Technical Summary

Benefits of technology

This approach increases naphtha yields while minimizing the production of dry gas and coke, maintaining reformulation activity, and reduces olefin concentrations, thus improving the quality of FCC products.

Problems solved by technology

It has now been discovered that when contacting a product fraction from an FCC reactor with catalyst in a secondary reactor, higher catalyst temperatures increase the undesirable cracking to dry gas and LPG.