Slurry reprocessing and minor off-taking

I think oil slurry reprocessing should be stopped rather than being used for external discharge; aside from increasing the amount of coke produced, oil slurry reprocessing offers little benefit and more harm than good. The outward movement shows that volume remains at a moderate level under the given conditions

It wasn’t ejected properly; was there any reprocessing?

We do not reprocess the oil slurry; the solid content is controlled through minor external discharge

It cannot be generalized; a comprehensive assessment is required based on factors such as the properties of the raw materials, the coking rate, the solid content of the slurry, and the density of the slurry； For example, in a set that used full paraffin oil catalysis as seen before, the amount of coke formed was insufficient, resulting in a low temperature in the regeneration bed; this led to excessive waste of combustion oil. By increasing the reprocessing of the slurry, the bed temperature could be controlled and the solid content remained within acceptable levels, so external discharge was stopped ； Sometimes, the amount of slurry recycled is high, and the amount of raw coke produced is also high; yet the solid content doesn’t decrease, so it becomes necessary to dispose of the slurry externally ； I have also seen a system in which the atmospheric vacuum residue is fed entirely to the bottom of the catalytic fractionator; from there, it is drawn out, cooled to 200–220 degrees, and then fed into the riser reactor. This approach is commonly referred to as full reprocessing, and no slurry is discharged outside in this process.

Catalysis using paraffin oil is now quite rare. . . However, it did burn a bit too much; some oil slurry can be reprocessed to maintain the bed temperature, and that should work. However, the energy consumption might be a bit higher, and the yield will also be affected to some extent; but compared to normal operation of the device, this loss is not significant.

The role of reprocessing slurry oil is not particularly evident in current refineries; it is not about recovering this catalyst. It is more aimed at participating in the adjustment of thermal balance. This is particularly evident in heavy oil catalysis. The reason is that once this portion of the slurry is fed back into the riser, it has a high tendency to coking, and the cracking effect is not as good as expected; most of it turns into coke and dry gas components. Furthermore, this portion of the catalyst can escape from the settler; thus, even after returning, it either goes back to the settler or ends up in the regenerator cyclone separator. How much can be recovered depends on the efficiency of the cyclone separator in the regenerator. Personal opinion

The slurry must have a certain amount of discharge to prevent an excessive accumulation of solid content in it, which could cause wear on the slurry pump and the reprocessing nozzles, as well as accelerate coking; therefore, it is essential to ensure a proper level of discharge!