OLI FCC Overhead Consulting Services
Fluidized Catalytic Cracking (FCC) Main Fractionator Overhead systems are highly susceptible to corrosion and fouling due to the inefficient removal of chlorides in the desalter. NH4Cl salts deposit on the fractionator top trays as well as the overhead system, fouling the unit and causing corrosion. Refiners apply a water wash (intermittent or continuous) in the overhead lines and exchangers, with periodic tower washes to remove any salt deposits on the top trays, piping, and heat exchangers. Fouling of the top trays and overhead system disturbs the delicate hydraulic balance of the FCC Unit. Once the tower fouls, the backpressure through the tower eventually reaches the regenerator and limits the main air blower (MAB). Once the MAB is rate-limited, the refiner may need to reduce rates to the FCC to achieve the same conversion rates, reducing unit profitability.