Potential constrains in FCCI at minimum feedrate

[rumirav]

Dear all,

My question is related with the potential problems that could appear when the feedrate in a FCCU is reduced to the technical minimum (turn-down) or below.

- According to your experience, what is the minimum feedrate that can be processed in a FCCU? 60% of nominal feedrate or does anyone operated below this point?
- Which are the most likely limitations that could appear in this point?
1. Insufficient gas flow rate to the wet gas comppresor?
2. Insufficient pressure or delta P in feed nozzles? Problems to obtain a suitable vaporization?
3. Insufficient coke production to close heat balance?
4. Insufficient liquid-vapour traffic in the main fractionation?
5. Any other limitation?

Thank you very much for your collaboration

Best regards

 

[JLSeagull]

Is recycle excluded?

 

[rumirav]

Dear JL Seagull

We use a slurry recycle in normal operation (aprox. 10%wt. on fresh feed) and we would like to maintain this recycle during operation at low feedrate. We do not have dedicated slurry recycle. Slurry comes bacj to the riser through the same feed nozzles than VGO