Abstract: The online water washing technology is the technology for removing salt deposition in the top circulation system of fractionating tower running under the conditions of full load operation. The application results in an 800 kt/a fractionator show that the salt deposition in the upper part of fractionator is effectively controlled, leading to a stable and reliable operation in the top circulation system, and no salt deposition exists; the online water washing with different water content has no impact on the distillation range of gasoline and diesel on specification. However, the water content must be controlled more than 50% to ensure the stability of the top circulation during the process.

Key words: residue fluid catalytic cracking, fractionating tower, salt deposition, water washing