Abstract: Slurry pump is an important part of fluidized catalytic cracking (FCC) unit. The granularity of insoluble particles, pyrolysis behavior, morphology and elemental composition of the samples obtained from different positions in the FCC slurry pump in Shijiazhuang Company were characterized to investigate reasons that caused the clogging of the filter inlet of the slurry pump. Two kinds of cokes were found in the sludge deposition: small size coke powder and block particles. The results show that the small size coke in the sludge deposition of the pump inlet has a similar H/C atom ratio with the coke from coking unit, but significantly different from the coke blocks in the sludge, which is thought to be generated by FCC reaction, indicating that the small size coke powder in the sludge is the product of pyrolysis reactions of high temperature slurry. It is this coke powder produced due to the changes of operation conditions that causes the filter clogging.

Key words: catalytic cracking slurry, slurry pump, filter clogging, cause analysis