(28a) Mitigating Chloride Content On Vacuum Diesel

Traditionally, diesel is recovered as direct product from the atmospheric tower. With the growing demand and tighter specifications, vacuum diesel recovery has becoming an attractive complementary production strategy for many refiners.

The chloride content tends to be higher in vacuum diesel than in the direct atmospheric diesel. Although in low concentration (ppm level), chloride can drastically affect the downstream diesel hydrotreating unit, including plugging, corrosion and costly unscheduled shutdown.

Pilot and field tests have been conducted to determine how chloride content in vacuum diesel is related to vacuum tower operating conditions.

The results show that a higher fractionation reflux rate, besides the expected sulphur and end boiling point reductions, has the benefit of mitigating the chloride content in vacuum diesel.