Abstract
Increasing plant capacity is one of the critical changes that should be assessed thoroughly to avoid the possibility of increasing corrosion risks and introducing hazards to operations, processes, and control parameters. A systematic approach was developed and utilized to directly assess the impact of the capacity increase in a hydrocracking unit. This study has determined the possible changes in corrosion drivers and subsequent corrosion loops, risk matrix, and inspection strategies using a quantitative risk-based decision process. The sensitivity analysis revealed that increased capacity requires focus in the following areas: erosion-corrosion due to velocity increases and ammonium bisulfide (NH4HS) fouling. Process simulations along with Risk Based Inspection assessments were employed. The study concluded that the capacity increase is feasible provided: the water wash treatment is increased to account for additional NH4HS, additional on-stream inspection points are provided for systems susceptible to erosion-corrosion, and selective metallurgical upgrades are planned for improved sulfidation resistance.
