Reducing Iron Carryover to FCC Feed Through Crude Pretreatment

The refinery was experiencing persistent iron contamination associated with feed to its fluid catalytic cracking unit. Conventional desalting removed water and salts, but the investigation identified iron-rich inorganic particles continuing into vacuum residue and the downstream process.

The objective was to improve separation of these particles upstream of the FCC unit. The program also needed to address desalter solids discharge, phase separation and oil in the effluent as connected operating concerns.

Chemical treatment was introduced at the crude-pump inlet to provide mixing before desalting. The program also adjusted interface level, mixing-valve differential pressure and backwash operation. Early interference from ultrasonic equipment was reported; the later trial period used the chemical treatment without that equipment.

The case account reports a decline in vacuum-residue iron during continuous treatment, followed by a rise after chemical withdrawal. The reversal is relevant to assessing the treatment contribution. Interpretation also needs to account for the desalter adjustments made during the program.

A similar trial should track crude quality, solids characteristics and desalter settings alongside iron measurements. Sampling locations should distinguish crude, desalted crude and downstream streams. Recording chemical and operating changes together helps identify the conditions associated with improved solids removal.