The solid content of the slurry is high; help!
Thread Content
Since the unit started operating recently, the solid content in the slurry is relatively high, at 8.8 g/l, while the normal value is 3 g/l. Increasing the amount of material sent for external disposal or reprocessing has had little effect； At the same time, after operation began, the pressure at the feed nozzle increased; the normal value is 0.550–0.65 MPa, but it is now at 0.75–0.85 MPa. It is suspected that the nozzle is blocked, and the high line speed has caused damage to the catalyst, with fine particles being carried over to the distillation process. The catalyst components in the slurry were analyzed: 0-20, 20-40, 40-60, 60-80, 80-110, 110. The corresponding values are 1, 17.9, 38.5, 19.9, 84.6, 11.1 for the respective ranges. For the ranges 2, the values are 13.8, 56.2, 24.18, 5.29, 1.17, 1.07. The data for category 1 corresponds to the year 2019; at that time the solid content in the slurry was high. After maintenance work, it was found that the coarse spinners in the settler were worn out ； The 2# data refers to the figures from the period since work started recently ； When comparing the two, the proportion of the 0-40 component increases significantly. What can this indicate? Is the breaking point of the catalyst located in the riser?
This post was last edited by qugd on 2020-3-20 at 10:23. The solid content in the slurry mainly consists of residual catalyst powder and carbon particles that were not completely burned during regeneration; this indicates that these solid impurities are not properly separated during the separation process. It may be possible to improve the conditions by increasing the amount of slurry that is discharged externally. Based on the analysis of the data, the particle size is concentrated below 60um, indicating that there is significant catalyst fragmentation; it is therefore advisable to supplement with new catalyst. Catalyst crushing is a complex process, and such data cannot indicate where in the FCC unit the catalyst was formed; wear is one factor, but the regeneration section could also be the cause.
Will the unit be restarted after maintenance or after an emergency shutdown? If operations resume after maintenance, were new nozzles installed? A high nozzle linear velocity may lead to catalyst fragmentation; it might be worth trying to reduce the flow rate of the atomizing steam to see the effect. Additionally, the particle size distribution of the catalyst in the slurry varies significantly, making accurate analysis difficult. Catalyst crushing and agent leakage from the settler are two issues; please provide the particle size analysis results of the balance agent, and we will take a look together.
During the inspection in July, the coarse cyclone grinder was worn out, at the same old spot where it had been repaired last time.