The issue of catalytic catalyst removal
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In normal production, it is inevitable to remove the catalyst; how can we avoid an excessively high level of dilute phase? ? ?
During the agent removal period, there was no issue of excessively high dilute-phase temperature in our unit. Could it be that after the agent was removed, too much fresh agent was added, resulting in excessive catalyst activity?
You removed the agent too quickly; next time, do it more slowly
When discharging the agent, do so slowly and control the bed temperature; if necessary, cut off the main air flow.
The regenerant has never caused overheating in the dilute phase; overheating occurs only when fresh regenerant is added.
Reply to 5# LQ198619 Why? Brothers, how did you manage to prevent the desorbent from being in a dilute phase and to keep the flue gas temperature from exceeding limits?
Is this because, after the bed level decreased, carbon monoxide wasn’t completely burned in the dense phase? If so, it can be adjusted by modifying the ratio of additives.
Reply to 7# yfyuan0717: Additive? Definitely will be added. After removing the agent, the original fluidization equilibrium was disrupted. Simultaneously with the agent removal, the main air flow rate was reduced. Yet, the flue gas temperature still exceeded the limit! It’s a bit frustrating! I don’t know how to adjust it properly?
It seems your device is too fragile; the slightest disturbance in balance can trigger a chain reaction. Lean combustion indicates that the oxygen supply is greater than the oxygen demand. When unloading the agent, control the speed and go slowly. The main air volume can be reduced, or the amount of slurry recycled can be increased. Give it a try; we’ve never encountered this situation before either.
Ultra-high diluent lean-phase temperatures seem to occur infrequently; it is mainly a problem with the balanced distribution of oxygen supply in the bed.
I think the key is to control the desizing speed well. If there is a lean-phase superheat, the main air flow can be reduced, or a CO combustion aid can be added. We have not encountered this issue when unloading the catalyst. It is hoped that the stable operation of the reaction system can be maintained during catalyst removal