Revamps 2026 Issue

Figure 5 Primary cyclone inlet refractory damage

Figure 6 Secondary cyclone dipleg erosion

separation and cyclones with only small amounts of hydro- carbon and steam in the dilute phase. As a result, they are subject to internal coke formation, particularly around the riser crossover ducts, top of cyclones, support members, and in the dome area. The degree of coking should be com- pared with prior turnaround results. A significant increase in coking versus typical should be investigated. Excessive coke build-up in the dome may show some steam ring damage or inadequate dome steam rates. Designs include a baffle to prevent hydrocarbon in the dome area. For these designs, excessive coking may be the result of damage to the dome area or insufficient steam. The steam meter should be checked for accuracy. Large pieces of coke should be removed to reduce the likelihood of coke combustion during the heat-up phase of the start-up. Inspection will often require coke removal to inspect welded areas. As with the other equipment, any issues with temper- ature and pressure instruments should be included in the turnaround scope. All pressure tap nozzles should be checked to ensure they are clear. The location of pressure and temperature instruments should be verified. Prior to start-up, all purge ROs should be verified for size and proper installation. The condition of steam distributors, such as dome steam rings, cyclone steam, primary cyclone pre stripping steam (see Figure 5 ), cyclone bathtub grid and other internal piping, should be inspected and damage noted. Damage should be investigated for possible upgrades, particularly if similar damage was noted in the prior turnaround. External wear to the riser termination/reactor cyclones

should be noted for possible impingement issues. Reactor wall refractory wear is common and should be addressed by refractory inspection. As with the regenerator cyclones, the riser termination area and reactor cyclones are subject to wear, particularly around the inlet area, the internal cyclone back wall (target area), cross-over duct areas, and around the bottom of the dust bowl outlet into the dipleg. Reactor rise termination and cyclones should be inspected for unusual wear patterns, wear to hex mesh, coke build-up in cyclones, and damage. Ensure inspection of unlined por- tions of the dipleg for wear (inspection should also check dipleg thickness). Inspect for dipleg hole-through, particu- larly in transition areas from the lined to unlined sections of the dipleg. Today, diplegs are often inspected with cam- eras. Coke around the back side of the secondary cyclone is common and should be removed if excessive to prevent spalling of the coke, potentially plugging the secondary dipleg (see Figure 6 ). Reactor cyclone trickle valves are subject to wear and thermal deformation. The trickle valve hinges should be free of coke and move freely. Note the location of any wear (wear at the top would show vapour egress into the cyclones). Gas leakage up the dipleg is a common issue causing internal dipleg and dustbowl erosion. Replacement of the entire trickle valve is a widespread practice to lessen turnaround repair scope and issues matching trickle valve clearances. Units may use counter-weighted flapper to seal diplegs. Like the trickle valves, inspect for proper flapper seal and free movement. Any deformation or sticking should be

Figure 7 Steam distributor nozzle erosion

Figure 8 Reactor overhead isolation valve coke build-up

Revamps 2026