Abstract: A new combined trapezoid double spray tray (CTDST) was developed for high gas phase and high capacity gas-liquid mass transfer operation. The structure of double spray tray could reduce the initial speed of the spray droplet, the pressure drop of the tray and the tray entrainments could be improved effectively. The application of CTDST in the FCC fractionation tower of Huabei Petrochemical Company showed that the gas-liquid flow rate in the tower was high, the processing capacity increased significantly, the pressure drop of the tray was low and the separation efficiency was high; the kinetic factor of empty column reached 3.2 (m•s-1)•(kg•m-3)0.5 and the kick volume of downcomer reached 130m3•m-1•h-1. The gap between the 95% cut point of gasoline and 5 % cut point of diesel fuel, and the gap between the 95% cut point of diesel fuel and 5 % cut point of recycle oil were 34 ℃ and 30 ℃, respectively. The 5 % cut point of slurry oil reached 415 ℃.

Key words: column plate, mass transfer, fractionating colum, catalytic cracker