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FCC regenerator flue gas line refractory repeated failure is being experienced. Exact location of failure is at immediate downstream of the flue gas slide valve (Double disc type). Even after replacing the refractory in turnaround, hotspots developed early into unit operation. The dryout was carried out as per standard procedure and there were no thermal shocks due to sudden feed outage. Kindly suggest the reasons for this failure and if any modification in refractory type of design may help to avoid this in future.

Mar-2022

Answers

Togar Manurung, Pertamina, togar@pertamina.com

It is not uncommon to hear the Hot Spot at transition area or Orifice Chamber Inlet section which downstream Flue Gas Stack Slide Valve and mostly several factors may involves. If the Refractory design (include anchorage) and casting has applied properly include at the transition zone then its need to review the Stress Analysis on this system from Overhead Flue Gas line Regenerator, DDSV and Orifice Chamber. We do not know what kind FCCU type and license you have

May-2022
Steve Chenrack, Morgan Advanced Materials, steve.chernack@morganplc.com

It's very unlikely dry-out is the issue. The devil will be in the details including; refractory type and design of the area, what the refractory looked like prior to repair / tearout and review of the hot spots before and now. Sorry not to have a more specific recommendation but these all have to be treated as unique situations to find the root cause.

Mar-2022
Peter Blaser, CPFD Software, peter.blaser@cpfd-software.com

Did the refractory problems start after a change to the slide valve design or a significant increase in catalyst losses? We've observed cases where the acceleration of flow through the slide valve causes a stream of catalyst fines to locally impact walls immediately downstream of the flue gas slide valve, leading to higher than anticipated erosion in that area.

Mar-2022
Jeffrey Bolebruch, Blasch Precision Ceramics, Inc., jbolebruch@blaschceramics.com

As a supplier of prefired net shapes, I cannot speak to the dryout schedule. It sounds as though you are cognizant of the need to properly dry out/cure out the material, so the odds that it is related to improper placement are smaller, although not zero. Perhaps there is some non-homogeneity in the material, or some reason why specific area(s) failed to fill. Perhaps it is a tight/difficult area to fill. You might consider a precast shapes if it is a complex area or a small diameter, that could hinder your ability to place the material.

Mar-2022