Revamps 2023 Issue

By upgrading the secondary cyclones, the project deliv- ered a substantial return on investment. The efficient removal of coke and solids from within the secondary cyclones ensured the downstream fractionator’s smooth operation and minimised the risk of costly shutdowns and manual cleaning efforts. Case study 3: Regenerator cyclone replacement to increase feed and air rates In a medium-sized unit with a capacity of 75,000 BPD, the replacement of eight pairs of regenerator cyclones became necessary after more than two decades of service. The motivation behind this overhaul was driven by the aim to enhance unit capacity by upsizing the cyclones. Additionally, the unit was suffering from higher-than-expected catalyst losses, which posed a significant economic challenge. To address the challenge, a comprehensive revamp strat- egy was undertaken. The core of this strategy involved the replacement of the regenerator cyclones while simulta- neously increasing their size to accommodate the desired unit capacity expansion. In addition to the cyclone replace- ments, the revamp included a transition to a hopper-less design for the secondary cyclones and the installation of upgraded trickle valves. The changes implemented yielded significant benefits for the unit’s performance and efficiency. The most nota - ble achievement was the substantial reduction in catalyst losses from the initial range of 5-7 TPD to a significantly lower level of below 2 TPD, translating into cost savings. Additionally, the adoption of the hopper-less design for the secondary cyclones and the incorporation of upgraded trickle valves contributed to enhanced operational stability. Moreover, analysis of the flue gas scrubber water indicated an average particle size within the range of 5-10 microns. This revealed that the new regenerator cyclones dramat- ically improved catalyst retention, including catalyst fines, allowing only the smallest catalyst particles to escape the regenerator for capture by the scrubber. Overall, the revamp not only addressed the initial challenge of high catalyst losses but also yielded improved economic performance and reduced environmental impact. Conclusions By optimising the FCC unit cyclone technology, the devel- opment team has resolved the issues commonly encoun- tered in running traditional cyclones 30 or 40 years ago. Since then, their cyclone-related shutdowns or slowdowns have reduced by more than 90%. Recent surveys reveal conventional cyclones are frequently the cause of ongoing industry problems in FCC operation, indicated by high catalyst losses and severe erosion

Recent surveys reveal that conventional cyclones are frequently the cause of ongoing industry problems in FCC operation, indicated by high catalyst losses and severe ero- sion. There is a general perception that FCC cyclones are inherently high-maintenance components that need to be replaced over time. In many cases, cyclone-related issues eventually lead to unscheduled shutdowns and have a sig- nificant impact on operational and financial performance. In attempting to resolve this situation, the inherent limita- tions of conventional cyclone technology become evident. Past strategies revolved around adopting longer barrels or hoppers within conventional cyclones to counteract erosion and the threat of an unscheduled shutdown. This approach faces challenges, particularly when implemented in FCC units that have undergone debottlenecking initiatives. Constraints arise from vessel size, as the existing infrastruc- ture might not easily accommodate larger cyclones, necessi- tating substantial modifications or even vessel replacement, which introduces the potential for project scope expansion. A more cost-effective approach involves exploring an integrated design solution that utilises enhanced cyclone technology, such as vortex stabilisers and coke catchers. This option offers operators a range of advantages, includ- ing the potential for project cost savings by reusing existing vessels. Furthermore, by reducing cyclone erosion damage, enhanced cyclone performance leads to diminished operat- ing costs associated with fresh catalyst addition and down- stream cleaning. Additionally, the implementation of this technology has the potential to reduce turnaround duration and associ- ated costs, particularly when cyclone repair is a critical element of the turnaround process. Above all, it could lead to a decrease in unscheduled shutdown occurrences and smoother operation. Mohammad Umer Ansari is senior Technologist, Fluidisation Tech Support and Design at Shell Catalysts & Technologies. He is responsi- ble for technical services for optimisation, troubleshooting and catalyst selection for FCC units in the Americas, and the design of grassroots and revamp projects for FCC units. He has worked in the refining and petrochemical industry for 25 years and holds a bachelor’s degree in chemical engineering from Malaviya Regional Engineering College, Jaipur, India and a master’s degree in chemical technology from the Indian Institute of Technology, Mumbai, India. Todd Foshee is FCC Licensing Technology Manager at Shell Catalysts & Technologies. He leads the licensing efforts for Shell’s FCC tech- nology to third-party customers and is part of a team that provides the process design on FCC projects to both Shell and third-party cli- ents. He has BS and MS degrees in chemical engineering along with 30 years of experience in the hydrocarbon processing industry that includes process design, site support and operations. Robert A Ludolph is Team Leader, Fluidisation Tech Support and Design at Shell Catalysts & Technologies. He leads a team provid- ing technical advice, assurance, and design to advance the process technologies and operations at Shell wholly-owned, joint venture and third-party licensee sites. He has BS and MS degrees in chemical engineering and is a registered Professional Engineer with 45 years of refining experience, including 38 years specialising in FCC.

Revamps 2023