Conditions prior to feed injection in a catalytic cracking unit before startup
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What are the conditions before feeding material into a catalytic cracking unit at startup?
The catalyst is flowing properly; the temperature at the outlet of the riser is around 530 degrees. The steam nozzles are functioning correctly, water content in the feed has been eliminated, and the flow rate of the slurry pump is normal.
Additional note for floor 2: The regeneration temperature must be no lower than 650 degrees.
This general principle remains consistent: 1. The regenerator temperature reaches 650-700℃； The reaction temperature reaches a level slightly higher than the normal reaction temperature ； 2. The fluidization and circulation in both units are normal, and the pressure difference between the two units has been adjusted to a positive value ； 3. The fractionation stabilization system is capable of meeting the required operating conditions: proper operation of the slurry circulation, secondary circulation, and top circulation; effective water separation; accurate liquid levels in all towers; and a bottom temperature of over 180°C ； Stable system with three-tower cycle) 4. The compressor meets the conditions for increasing speed. 5. The reaction distillation unit is ready for pressure control during switching. 6. The solid content in the slurry is within normal limits. That’s all I can think of for now; please feel free to add more.
Additional note for the fourth floor: The waste heat boiler needs to be started in advance, or steam from outside the system should be introduced
The overall temperature of the settler must be at least 380 degrees; it’s better if it can be higher. Currently, the quality of the raw materials isn’t very good； The reaction temperature can be increased further; I usually set it above 550 degrees ； The slurry pump must be able to withstand challenges and operate steadily ； For smaller units, a waste heat boiler is installed directly; for larger units where it is difficult to allocate personnel, a waste heat boiler is added as well. One more thing.
What was said on the 4th floor is very specific; I agree.
A cold reflux at the top of the tower should be established; under normal circumstances, the temperature at the bottom of the tower should be no less than around 200 degrees. The desulfurizer circulation in the refining system is operating normally. The gas phase is used to introduce liquefied gas in order to establish liquid level and pressure.
Two additional points: it seems that the anti-scorching specifications require the temperature at the outlet of the riser to be above 530°C, and the temperature at the top of the settler to be above 430°C.