Abstract: A newly purchased small fixed fluidized bed FCC evaluation unit was installed, debugged and modified. The installation position of the preheater was changed, and the connection pipeline between the preheater and the reactor was shortened. The results showed that after revamping, the repeatability of product distribution was improved. The stability of the rotor flowmeter was improved and the drag and delay of CO2 curve caused by flow fluctuation and gas resistance of CO2 infrared analyzer was reduced by increasing the gas condensation depth at the front of the CO converter, leading to a good repeatability of coke data. By increasing the pressure of the device system, the production rate of LPG and propylene were reduced, the results close to the data of the industrial device. The revamping work can better guide the selection of catalyst formulation and the comparison of performance

Key words: fluid catalytic cracking, fixed fluidized bed, preheater, flue gas condenser, reaction pressure, repeatability