Lakshyavir Singh - HMEL
Turnaround critical paths across refineries are decided by the activity schedules in the Reactor Regenerator (R&R) system of FCC unit, hence it becomes important to evaluate job scope as close to actual to avoid uncertainties and surprises during the turnaround that may result in schedule & budget overrun.
Past shutdown experiences/ reports and recommendation from OEM, Licensor, Inspection teams play major roles in compiling job scopes, however, it becomes difficult for the 1st Turnaround, wherein such reports, inspection recommendations and equipment history isn’t available and the job scope is to be prepared.
This paper discusses how one can plan in advance for the surprises even for the 1st Turnaround.
Fluidized catalytic cracking itself has gone through an evolution phase from generic Petro FCC to R FCC to Deep Catalytic cracking which processing capacities reaching unthinkable proportions.
FCC Technology by the various licensors utilizes basic functions of similar components, hence the susceptible regions in the R&R, probable damage mechanism, and their repairs have been analyzed and recorded. For instance for air dispersion in regenerator one may utilize the cylindrical ring; square grid or circular plate but the nozzle type remain the same (size & quantity may) and the damage due to the erosion of the exposed surfaces is observed during any Turnaround. If the erosion is limited to the tip of the nozzle then minor metal build up by welding is sufficient enough, else in case the nozzle had detached from the grid and the surrounding refractory is also damaged then one has to replace the nozzle, weld it to the grid and apply the refractory lining.
The parameters and observation discussed here to give a clear indication of what kind of surprises might be observed when the equipment is inspected from inside, for instance, high BS&W in the slurry circuit indicates high catalyst attrition thru the cyclones in reactor, coupled with high cyclone entry velocity and other factors may have caused erosion/ damages in the cyclones surfaces both refractory line or metallic. Planning ahead for these ensures quick mitigation during the course of Turnaround.
The most important key for Turnaround Planner is to understand how well the unit is operated in the period since last Turnaround/commissioning.