Home › Forums › CatCracking › FCCU-CatCracker › Valero's St. Charles Refinery to change MSCCU to Riser Cat › RE: Valero's St. Charles Refinery to change MSCCU to Riser Cat
Previous posters were sort-of right. The current MSCCU carries over an average of 20 tons of catalyst into its scrubber system every day, instead of the typical 3-4 tons. The current design, with its external cyclones and “cyclone separator” vessel just does not work. Conversion rate is low (72-75%), dP across slide valves is very high due to the height of the unit, and there isn’t enough residence time. Because of the high erosion in the system, refractory reliability is low and has brought us down numerous times due to hot spots that can no longer be controlled externally. Slide valves get severely damaged (beyond anything any of the manufacturers have ever seen) and the overall reliability of this unit just stinks. It keeps us very busy and we will all be extremely glad to see this thing go. Valero is still doing well, especially St. Charles, and it really is no surprise to us that Corporate is doing this revamp now.