ASPHALTENE PRECIPITATION PRIMARY CRUDE EXCHANGER FOULING MECHANISM.

Research at Exxon Chemical Co. has shown that asphaltene precipitation and subsequent carbonization is the major mechanism in crude oil heat exchanger fouling. Further study has found that the mere presence of asphaltenes does not necessarily mean a crude oil will foul. Asphaltenes that are incompatible with the crude oil chemistry and composition have a much greater tendency to precipitate and foul. In order for the refiner to be able to determine the AFC index on a daily basis, Exxon Chemical Co. has developed the AFC analyzer. The AFC analyzer quantifies the asphaltene incompatibility in crude unit feed and predicts the fouling potential for that crude oil. Numerous dispersant-type and multifunctional antifoulants are available to mitigate crude unit fouling. The savings and operating benefits, of course, will vary depending on a refinery's history, the system configuration and operating parameter and the types of crude being run.