Bryan Lewis - CatCracking.com
Operators have experienced leaks of catalyst from the reactor and regenerator. On the regenerator side, they are related to cyclone performance as well as other containment systems like third stage separators, ESP’s etc. On the reactor side catalyst losses typically end up in the slurry oil product and do not become “leaks”.
Leaks also occur from TI at the inlet of fractionator and at the fractionator bottom, on the vapor line, in expansion joints between slide valves and reactor standpipe, and many more places. Catalyst can erode thermowells – it does not lake long for them to erode rapidly so early detection is critical. On the fractionator side, entrained catalyst can erode slurry piping. On the slurry / feed leak issue, there are quite a few troubleshooting steps to detect feed in the fractionation bottoms. Since the feed is uncracked and if the leak is bad enough, the fractionator bottoms level starts to climb and operators will have to increase the release (CLO or LCO / HGO). Operators must go out in the field and check the feed / slurry exchangers and take it out of service for tube repair. At this time it would be a good time to perform an eddy current test on the tubes. This information can help you determine if the other exchangers need to be removed from service in the near future.
Leaking of feed into slurry product in feed / slurry exchangers results in bypassing the unit. This is more a performance issue than a safety / environmental one. When this happens the apparent bottoms yield and API gravity will increase and often the catalyst gets blamed (of course) for “poor bottoms cracking”. If the feed has significant 650F- content it will also look like poor fractionation.
Attendees are invited to share additional leaks they have experienced. Then we’ll perform an informal high-level root cause failure analysis.
How was each leak detected, for example console alarm, operator rounds, inspection, maintenance, turnaround or other? How high was the risk to personnel, equipment, or environment? Was the repair minor or significant in terms of time, expense, and lost production. Could it have been avoided through design, maintenance or some other way? Other recommendations?