Technical exchange on catalyst bed fouling prevention in catalytic units
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We experienced several instances of bed blockage in our catalytic cracking unit; each time, we removed all the loosening air, steam, and main air. Nevertheless, the temperature of the dense-phase bed dropped very rapidly, so we had to maintain its temperature by injecting a small amount of combustion oil, along with some unpurified air to aid combustion. I would like to ask fellow sailors: when performing the bed-sealing procedure, does the bed temperature drop quickly? , and then the key task to carry out – how long can one stay in bed without moving at most?
You’re already at the end of your life; spraying burning oil violates safety procedures. A little bit of unpurified substance isn’t enough to completely burn off the burning oil on the catalyst
It means stopping all the wind; in the worst case, it can last for a day.
You’re right, but we’ve done this procedure five times already, and we’re worried that there might be some problems. That’s why we also use the main air flow to activate the bed layer from time to time, but I still feel that the bed temperature drops too quickly!
Once it’s covered, stop blowing air on it from time to time; surely it will cool down if you do that, right? And there’s also the issue of spraying burning oil into the bed – aren’t you worried about accidents occurring inside the regenerator?
Due to our particular circumstances, it is necessary to keep the bed sealed for four or five days; however, the natural cooling occurs too quickly, and such a seal cannot be maintained even for one day. Therefore, oil burning is used to maintain the temperature. Some unfiltered air is introduced during spraying, and once the temperature rises, the sealing process is resumed. After two or three days, normal air flow is used to stir the bed layer.
I think it’s better to raise the temperature all at once after completing the maintenance, by increasing the temperature of the main air as well.
I’ve never tried leaving the bed covered for 5 days; 1 day isn’t a problem at all.
If the bed is left unused for less than 3 days, there should be no problem. If it’s 3–5 days, during the recovery period, it might not be possible to inject the combustion fuel; in such cases, an auxiliary combustion chamber is needed. We have left the bed unused for up to 5 days in total
How much can your temperature drop in a day?
Finally, when the temperature of the generator drops to around 400 degrees, it is generally kept above 700 degrees before stopping the reaction process