Effect of Atmospheric Residue De-sulphurizer Unit Revamp on Increased Corrosion in Amine Regeneration Unit

摘要

Atmospheric residue de-sulphurizer (ARDS) unit in one of the refinery was revamped in year 2004 with a new online catalyst replacement technology process for increasing the operating run length as well as capacity of the unit. This paper describes the effect of the ARDS revamp on the increased corrosion problems in the downstream amine regeneration unit (ARU), where rich amine loaded with acid gas (H_2S) from the ARDS is sent for regeneration in to lean amine. The refinery uses mono-ethanolamine (MEA) as an absorber media for removal of H_2S from the hydrogen recycle gas of ARDS Unit. Lean amine is sent from ARU to ARDS and after removal of H_2S, rich amine is sent to ARU for regeneration. At the time of ARDS revamp in year 2004, detailed study of the ARU was carried out from process as well as corrosion point of view. After the study, options were proposed to overcome the limitations of the ARU unit to cater to additional requirement from ARDS after revamp. However, due to various constraints execution of those options was deferred. This has resulted in increased and accelerated corrosion of various equipment (e.g. exchangers, towers, vessels etc.) and piping in ARU. On-stream leaks resulting in health safety and environment (HSE) hazards and increased maintenance costs/shutdown durations. The paper describes in detail the corrosion study carried out, and various measures adopted to mitigate and control the corrosion degradations.