Abstract: During the maintenance of a 2.20 Mt/a heavy oil catalytic cracking unit in a refining and chemical company, in order to solve the problems of uneven distribution of coked catalyst in the dense phase bed of a single counter-current regenerator and the high resistance of bubble phase and emulsion mass transfer, which limits the desulfurization efficiency of sulfur transfer agent, the spent catalyst distributor was changed from “boat” shape to “Y” shape, and a layer of Crosser grid was added. After remodeling, the SO2-containing flue gas was distributed uniformly in the dense phase bed, which reduced the mass transfer resistance and enhanced the adsorption desulfurization efficiency of the agent. Under similar regeneration conditions, the amount of PUS (pick-up sulfur) of sulfur transfer agent was doubled, the use of additives was reduced by 40%, the ammonia consumption of the flue gas purification system was reduced by 40%, and the cost of additives and the operation cost were significantly reduced. At the same time, the appearance of flue gas was significantly improved.

Key words: catalytic cracking, spent catalyst distributor, grid, sulfur transfer agent