Corrosion Investigation in Catalytic Continuous Reforming (CCR) Unit Using a New Method to Reduce the Risk of Unit Shutdown

This study explores the primary causes and prevailing corrosion mechanisms in Catalytic Continuous Reforming (CCR) units, with particular attention to high-risk zones such as the regenerator section, reactor effluent systems, and waste heat boilers. A novel corrosion mitigation approach was applied, combining Vapor-Phase Corrosion Inhibitor (VPCI) injection with real-time monitoring using electrochemical probes and weight-loss coupons. The investigation was carried out in a mid-sized refinery over a ۱۲-month operational period. Comparative data collected before and after VPCI implementation demonstrated a consistent reduction in corrosion rates exceeding ۶۰% across all monitored locations. To further analyze the impact of operational conditions, a multiple linear regression model was developed, considering variables such as temperature, chloride concentration, pH, and the presence of the inhibitor. The results confirmed a strong inverse relationship between VPCI injection and corrosion rate, validating the effectiveness of the proposed method. This strategy not only mitigated corrosion but also enhanced equipment reliability, optimized maintenance planning, and minimized the risk of unexpected shutdowns. The study underscores the importance of integrating proactive corrosion management practices in CCR units and recommends wider adoption of such methodologies in high-temperature refinery processes. The findings also revealed that corrosion behavior is strongly influenced by hydrogen temperature and pressure. Low temperatures promoted acid condensation, particularly from chloride-containing species, resulting in localized pitting and under-deposit corrosion. Conversely, high hydrogen temperatures increased the risk of High-Temperature Hydrogen Attack (HTHA), a metallurgical failure affecting the microstructure of carbon steel and low-alloy materials. Elevated hydrogen pressures further accelerated HTHA and Stress Corrosion Cracking (SCC), while insufficient pressures diminished the protective reducing atmosphere, heightening oxidation and acid formation risks. Flow-related parameters also played a critical role, as both inadequate and excessive hydrogen and catalyst flow rates negatively impacted corrosion performance.

کلیدواژه ها:

Corrosion ، CCR ، HTHA ، VPCI ، Low temperatures