Pressurized Regenerator Inspection Guidelines:
Following are recommended guidelines for inspecting a Pressurized regenerator. The Disengaging Hopper and Lock Hopper are included in these recommendations. The order of the recommendation is from the top down (starting at the top of Disengaging Hopper and working down through the regenerator to the Lock Hopper).
Disengaging Hopper
If the Regenerator is being emptied just for screen cleaning then the catalyst from the Regenerator may be transferred to the Disengaging Hopper using the Regenerator Unload Operation. In this case the Disengaging Hopper will remain full of catalyst. The Disengaging Hopper should still be isolated from the reactor circuit, depressured and kept under nitrogen atmosphere. In this case the Disengaging Hopper internals will not be inspected. However, it will still be possible to inspect and clean the screen insert in the Disengaging Zone gas outlet line. If this is done then it is essential that the Disengaging Hopper be completely and positively isolated, hydrocarbon freed and kept under nitrogen blanket. The open flange should be covered while the screen insert is removed, inspected, and cleaned. Then the screen insert should be reinstalled immediately and the system closed.
If catalyst is being replaced then the Disengaging Hopper will be emptied. It is normal practice to inspect the Disengaging Hopper from the manway. Catalyst remaining in the bottom head can be vacuumed out or swept into the bottom withdrawl nozzle and removed bottom nozzle. The catalyst restriction orifice on the pipe into the Disengaging Zone should be inspected to make sure it is free of obstruction. This is best done with a video camera / boriscope.
It is not necessary to dismantle the small I.D. middle and bottom sections of the Disengaging Hopper. However, if a suitable camera is not available to do the inspection without dismantling then it will be necessary to open these sections also.
Regenerator
There are 3 possible stages of regenerator inspection:
1. Before catalyst is unloaded
2. After catalyst is unloaded but before the inner screen in removed.
3. After the inner screen in removed.
Before Catalyst is Unloaded:
It is useful to evaluate the level of the catalyst in the regenerator before catalyst is removed. This helps identify any possible operating problems. In order to do this the line between the bottom isolation valve and the top of the regenerator must be removed. The top manway (usually nozzle FB on UOP dwg) and the top side manway (usually nozzle AF on UOP dwg) must be opened before catalyst is unloaded. The following can be observed