I would like to know the impact of processing slurry oil with high catalyst fines content (>2,000 ppm) in DCU. Are there refineries that process slurry oil with this quality? What is their experience on it?
FCC slurry has been successfully processed in Delayed Cokers. I have seen catalyst concentrations in the slurry that range from 0.16% by wt (1600 ppm) to 5% (50,000 ppm). The very high solids loading is more likely to cause erosion than the lower concentrations, but the erosion rate from the slurry catalyst content is low.
Normally, FCC slurry is processed at rates of 10% of the total fresh feed to the Coker or less. That dilutes the solids concentration. Erosion is dependent on a number of factors that include solids content, particle size, velocity, flow regime and a number of others. At typical catalyst concentrations the erosion rates are expected to be low. Many Cokers practice on-line spalling and the metal loss during that practice can be very high if velocities are not managed. Erosion from that practice can be much higher than any calculated erosion from catalyst fines.
Processing slurry oil in a Coker requires higher heater outlet temperatures to convert the material all the way to coke as those molecules have already been cracked at high temperature with catalyst, so the conditions in the Coker need to be more severe to fully convert them.
The catalyst fines will be contained in the coke produced in the Coker and will increase the ash content in the petroleum coke.