Energy Conservation Revamps in Fluid Catalytic Cracking Systems

Abstract

The FCC process continues as one of the major refinery technologies despite changes in refinery operations. The main fractionator/vapor recovery systems associated with many FCC units have the potential for significant gains in energy efficiency and product recovery through revamping.

Older FCCU designs did not take full advantage of the heat available in the main fractionator. These older designs typically reject large amounts of heat to air or water cooling while using steam to reboil towers in the vapor recovery unit. By selecting the proper location and rates of side pump around streams, heat available in the main column can be used to reboil most or all of the VRU towers. Revamps of this type may be undertaken as stand alone energy conservation projects or as part of a larger revamp aimed at improving the recovery of marketable products.

This paper will give examples of an older design with relatively inefficient heat utilization and a newer design incorporating recent trends in heat recovery. A case study describing an actual revamp of a main fractionator/VRU system will illustrate the potential for increased energy efficiency and improved product recovery.