Abstract: It was found that the dilute phase density of regenerator of FCCU rising abnormally, regenerator capacity reduction, and the bigger fine size in flue gas at outlet of three stage cyclones in Zhenhai refining branch. By analysis of Fe content on equilibrium catalyst and electron microscope scanning method, it recognized that the iron poisoning is the reason for these phenomena. Through taking measures: reducing the iron content in feed, increasing the rate of adding fresh catalyst, using low magnetic agent replacement, reducing the main air volume, the normal operation conditions were quickly achieved. The source of iron, symptoms of iron poisoning and the measures to deal with iron poisoning were further analyzed.

Key words: RFCCU, dilute phase density, iron poisoning