FCC technology - Recent advances and new challenges

The fluid catalytic cracking (FCC) process is one of the most important circulating fluidized bed processes. Although the FCC process has been in commercial operation for over 60 years, the technology continues to evolve in order to meet new challenges, which include processing more difficult feedstock and meeting more stringent environmental regulations. These new challenges demand new breakthroughs in circulating fluidized bed technology. This paper presents examples of recent advances in FCC technology in the reactor/regenerator section, where Shell Global Solutions* has made significant contributions. In order to process more difficult feedstock, such as residues, advances in feed injection systems, riser internals and riser termination technology work synergistically to improve FCC reactor performance. This paper will present the newest generation of the feed injection technology utilizing two-phase choking for fine atomization and optimized mixing, which is critical to residue cracking. Improved riser termination devices minimize post riser cracking by the combination of the unique design of pre-stripper cyclones and close-coupled secondary cyclones. Key advantages over a conventional close-coupled cyclone system include recovering the entrained hydrocarbon vapor at the "earliest" possible stage and minimizing coking in the vapor space of the reactor vessel. In addition, the Shell Global Solutions' developed proprietary "PentaFlow Packing" stripper internals will also be presented. It has shown excellent stripping performance at high catalyst flux rates and high reliability due to its non-plugging characteristics, critical to residue cracking. The unique catalyst circulation enhancing technology (CCET) has shown to improve standpipe stability, resulting in significant improvements in catalyst circulation rates. On the regenerator side, new developments in the Third Stage Separator (TSS) technology provide enhanced capability for achieving low particulate emissions in flue gas to comply with the requirements of more stringent environmental regulations worldwide.