How to judge riser coking
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When the device was shut down for maintenance, it was found that the riser was severely coked. The diameter of the nozzle changed from 400 to 100. How can we quickly judge the coking situation in the riser? Is there any good way to deal with it after coking? Ask an expert for guidance.
The coking status of the riser is mainly judged by the pressure drop. Last year, our device processed the coking of the heavy oil cracking nozzle online.
The fastest way can only be judged by the change in pressure drop in the riser~ It can also be judged by the fact that the reaction temperature rises slower than before after the plug valve opening is increased.
The coking status of the riser can be judged from two aspects. On the one hand, the pressure drop in each section of the riser is； On the other hand, it is judged by the temperature difference between the upper and lower temperature points of the feed nozzle, which is generally about 150 degrees, and the coking temperature difference becomes smaller.
The most intuitive judgment is that the pressure drop of the riser increases. Related to this, the opening of the regeneration slide valve will gradually increase until the valve opening has no effect on the circulation volume. The processing volume is limited by the circulation volume and pressure drop, and full-load stable production cannot be achieved.
Once coking occurs, it is difficult to deal with it effectively. You can only wait for shutdown to deal with it thoroughly.； In terms of operation, make appropriate adjustments to the refining and raw material conditions to maintain production.
It can be seen from the pressure drop in the riser that during operation, if it is found that the catalyst circulation volume cannot be increased, the regeneration slide valve is opened wide, and the reaction temperature does not change much, then the riser must be coked.
The direct manifestation is that the pressure drop of the riser rises.； When the processing amount is fixed, the valve opening increases and the pressure drop decreases, while the reaction temperature does not change significantly, and the density of the pre-lift section increases.
Can you tell me how it is handled online?
At the same processing capacity, the opening of the feed control valve should gradually increase!
The pressure drop changes in each section of the riser are the most direct, and the yield will also be affected. I suspect the second floor said it was processed online. Please come out and explain on the second floor.