Abstract: There was a serious fluidization problem with the regeneration standpipe installed in a 2.0 Mt/a FCC unit, resulting in a fluctuation range of reaction temperature about ± 10 ℃, a vibration amplitude about 3—4 cm of the regeneration standpipe, and a large area of hot spots at the inlet of the regeneration standpipe, which seriously affected the long-term stable operation of the FCC unit. First, the axial pressure distribution of the regeneration standpipewas measured, and the catalyst flow pattern in the standpipewas determined. The upper part of the regeneration standpipewas a dense fluidized state with a high concentration of catalyst. The middle part of the standpipewas a slug flow, and the generation, growth, and breakage of large bubbles lead to unstable catalyst feeding.Thiswas the main cause of standpipe vibration and reaction temperature fluctuations. The lower part of the regeneration standpipe is a dilute phase flow, while the catalyst flow in the lowerinclined pipewas a stratified flow, which was the main reason for the decrease in pressure accumulation in the regeneration standpipe. Among them, the catalyst feeding was carried out in a pulsed manner, which was the main reason for the fluctuation of reaction temperature and the vibration of the standpipe. By adjusting the aeration air parameters to improve the stability of catalyst feeding, the fluctuation amplitude of reaction temperature was reduced to ±3 ℃, and the vibration amplitude of the regeneration standpipe was reduced to about 1 cm. The vibration problem of the regeneration standpipe was significantly improved, and the research results could provide a basis for standpipe design and operation adjustment.

Key words: catalytic cracking, regeneration standpipe, catalyst flow patterns, aeration air, pressure distribution