Abstract: In view of the catalyst lost fault in FCCU, the inlet catalyst of the three-stage cyclone separator was sampled on site, and the particle size distribution and the scanning electron microscopy of the lost catalyst were analyzed. The results showed that there were multi-peaks in the particle size distribution curve of the sample, and the particle size corresponding to the peak value was 0.8, 9 and 30 microns, respectively. The first two smaller particle size particles were formed due to serious frictional wear and breakage of particles. On the other hand, because the separation efficiency of the cyclone separator decreases, the higher median particle size of the lost catalyst resulted in the peak of larger particle size.

Key words: FCC, catalyst loss, cause, particle size distribution, cyclone