Abstract: The FCC main fractionator usually has 2~3 pump-around (PA) heat exchanger. The lower PA has a higher temperature, indicating more valuable energy available. The effect of the heat removal optimization from the top and middle tower PA of the main fractionator on the operation was simulated using PRO/II simulation software. It is found that the increase of the energy recovery from the PA heat exchanger at the tower top and the first PA heat exchanger at the middle tower leads to an increase of the vapor and liquid phase load on the plate of the column. The model also indicates that under the conditions of stable heat recovery from the tower top PA, more heat removal from the middle tower PA needs more heat removal from the lower part of PA of slurry, resulting in lower total heat removal from the slurry (including upper part of PA of slurry), and higher yield of gasoline and diesel，while the slurry reduces slightly. The increase of heat removal from the tower top PA leads to a larger loading of both of gas and liquids phases at the lower part of the column, which makes the heavier component go up and more heavy components in gasoline and diesel products.

Key words: main fractionator, heat removal distribution, process simulation, vapor phase load, liquid phase load, pump-around heat exchanger