How to completely remove the catalyst at the bottom of the regenerator after shutting down a catalytic cracking unit

The distribution plate version is a bit better; with the distribution pipe version, it basically has to be cleaned manually every time shutdown occurs. Vacuum degassing after starting the degassing line will be faster!

During this shutdown, vacuuming was not performed, leaving a large amount of catalyst remaining at the bottom of the regenerator, which required manual cleaning and thus increased the workload significantly.

If the residue cannot be completely removed after each shutdown, is it because the vacuuming time isn’t long enough in the end? Using multiple commands several times yields better results.

After a catalytic cracking unit is shut down, if the catalyst at the bottom of the regenerator cannot be completely removed, this can be detected through certain operational parameters, such as the amount of catalyst stored in the regenerator, the bed density, and the density in each vertical and inclined tube. If the requirements are not met, ways need to be found to continue removing the agent.

The small amount of catalyst remaining can be completely cleared from the bottom of the regenerator by making significant changes to the main air flow before shutting down the main air supply; the downside is that it is all discharged into the atmosphere along with the flue gas.

In my opinion, whether a vacuum system is available or not is not the main factor determining how thoroughly the agent can be removed. I believe that during the desulfurization process, the main air flow should be continuously increased and decreased, or even the main air supply should be cut off and then reconnected; going through such cycles repeatedly is no problem when it comes to desulfurizing the regenerator. Given the poster’s question, I would like to ask: in a MIP riser reactor, when operations are halted, can the catalyst inside the riser be completely removed? Especially at the expansion section of the MIP? How do you operate it? We stopped work three times; each time, to remove the flanges at the bottom of the reactor for pre-lifting, 5 to 10 tons of catalyst had to be taken out. As for what the original poster mentioned about incomplete removal, the only option is to open a manhole and carry out manual cleaning or use machinery to create a vacuum for cleaning. .

It’s normal for there to be some residue left: lol, in the end, human intervention is still needed.

No matter how the catalyst is removed, there will definitely still be some catalyst at the bottom of the regenerator; it’s just a matter of how much. The remaining amount can be dealt with manually – there’s always a solution

We tried doing it the same way, but in the end there was still a lot of catalyst under the distribution pipe!

Even when the total inventory here reaches 0 during shutdown, it is still necessary to purge for over 4 hours in order to minimize the amount of catalyst used, but ultimately manual intervention is still required!