(84a) Heat Integration in FCC Main Fractionators

Fluid catalytic cracking (FCC) units help refineries balance the crude feed composition to meet downstream product needs by cracking higher molecular weight molecules into lower molecular weight molecules. The catalytic reaction in FCC’s occurs at high temperatures. After removing the catalyst particles the process enters the FCC main fractionator at 900+°F (482+°C). Recovering this heat provides the energy to preheat the FCC feed and to reboil the towers in the FCC gas plant. A well-implemented heat recovery system on the FCC main fractionator should allow the FCC unit to operate as an energy exporter and send heat (via steam or hot oil) to the rest of the refinery. Regretfully, no every FCC operates this well.

This review examines operating FCC units to illustrate interaction between FCC operating requirements and FCC heat recovery. Critical points in FCC operation are identified and methods to improve FCC heat recovery shown.