Monitoring and Management of Naphthenic Acid Corrosion in Distillation Units of a Petroleum Refinery

Abstract

The continuous increase in fuel prices at refueling stations and the costs of extraction, refining and supply chain management leads the Companies to purchase low-cost crude oils, characterized by high acidity and high sulphur content. The processing of such crude oils results in a drastic increase in corrosion rates, relative to sulfidation and naphthenic acid corrosion mechanisms, thus, it is necessary to take mitigation actions, conducting a cost-benefit assessment and reviewing inspection and maintenance plans. A petroleum refinery has implemented a monitoring system, through ultrasonic corrosion probes, and an inhibitor injection system at specific points in its atmospheric distillation units; the goal is to manage crude oil with TAN (Total Acid Number) value that not exceed 1.5 mg(KOH)/g.In this report, the layout and operation of the system are described, with a brief mention of the used inhibitor’s family; the choice of injection and monitoring points and the measured corrosion rate are presented for the first months in service.