Catalyst shutdown and removal
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During a catalytic shutdown, how should the catalyst in the reactor be transferred entirely to the regenerator? At this time, must the reaction pressure be higher than the regenerator pressure? Thank you!
When shutting down the reaction, it is necessary to ensure that the reaction pressure is higher than the regeneration pressure; this is mainly to prevent air from entering the subsequent units of the reaction, which could lead to spontaneous combustion of ferrous sulfide. Additionally, this approach allows for a faster catalyst conversion and results in less residual catalyst in the stripping section
During shutdown, the reaction pressure is higher than the regeneration pressure; when releasing the catalyst, it is necessary to keep the stripping section at a constant zero level and ensure that the density in the feed line returns to zero. The reaction and regeneration systems are then disconnected, and after installing the large blind flange, the catalyst is transferred and released multiple times.
The normal shutdown procedure is followed: the reaction feed is cut off, the normal differential pressure is maintained, and the catalyst in both reactors is recycled for a period of time to keep the temperature of the regenerator around 600°C. This is done to completely burn off the coke on the catalyst. Samples are taken to check the color of the regenerant, and the circulation between the two reactors is stopped as appropriate； At this point, the valve of the regeneration line is closed, the reaction pressure is increased to a level higher than the regeneration pressure, the catalyst inside the reactor is transferred to the regenerator, blind flanges are installed to isolate the reaction process from subsequent units ； As long as the agent removal route is unobstructed, that’s sufficient. To ensure safety and a fast rate of agent removal, the temperature is generally kept around 450°C ；
Here, we have finished unloading the catalyst and are waiting for the temperature of the distillation tower to drop before installing blind flanges.
Well, each company is different. In our case, we just need to carry out ventilation and circulation in the reactor to cause burning; we then observe the reaction results, and if they’re not satisfactory, we remove the material for screening and add new agents
Are you referring to the equipment in the catalytic cracking section? It seems like it’s the catalyst regeneration process in a fixed-bed reactor.....
I still don’t understand what was said above. Usually, we remove the balance agent and add it back to the regenerator when starting up the process
Catalytic cracking in a fixed-bed reactor? This is the first-generation catalytic cracking version – is it still in use?