Recent advances in FCC technology

Although the fluid catalytic cracking (FCC) process has been commercially established for over 60 years, the technology continues to evolve to meet new challenges. This paper presents examples of recent FCC technology advances through integrated R&D programs that bridge understanding in process science and engineering practice in which Shell Global Solutions 1 has contributed significantly. On the reactor side, advances in feed injection, riser internals and riser termination have been proven to work synergistically to improve reactor performance. Earlier generation of modem feed injection technology was introduced in the 1980's, using direct impact mechanisms for atomization. This paper discusses the newest generation of the technology utilizing two-phase choking for atomization, which has been demonstrated to be much more energy efficient, as validated by consistently achieving more uniform temperature profiles across the riser. The FCC riser is known for its shortcomings of density and velocity variations. The newest riser internal technology minimizes these shortcomings and promotes ideal plug flow. The FCC is a sequential reaction process in which many desirable products are the intermediates. Thus, cracking reactions must be terminated after a desirable reaction time; otherwise, desirable products will continue to crack, leading to excess productions of light gases and coke. Improved riser termination technology sharpens the termination of reactions by the combination of the unique design of primary stripper cyclones and close coupled secondary cyclones. On the regenerator side, conventional flue gas cleaning requires two stages of cyclone separation followed by electro-static precipitators (ESP) or scrubbers. 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 more stringent, particulate control environmental regulations. The majority of FCC units in the US have gone through various stages of de-bottlenecking, and many are limited by catalyst circulation. Catalyst circulation enhancing technology (CCET) has been demonstrated to improve standpipe stability, resulting in significant improvements in catalyst circulation rates. (C) 2006 Published by Elsevier B.V.