THE APPLICATION OF PROCESS ANALYSES TO PREVENT CORROSION IN SOUR WATER STRIPPER OVERHEAD COOLER TUBES

摘要

This paper discusses a successful experience in solving corrosion problems in the overhead system of a sour water stripper. In general, corrosion in this area is manageable unless the water discharged from a fluid catalytic cracking unit, which often contains a significant amount of cyanides, is processed. However, severe corrosion caused by condensed ammonium bisulfide (NH4HS) occurred in sour water stripper overhead condenser tubes fabricated from Type 316L stainless steel (SS). Higher corrosion rates were observed on the upper side of a tubes exposed to the vapor phase. By performing the process analyses using the electrolyte process simulation, the most influential variables determining the localized concentration of NH4HS and resultant corrosion rate were detected. The countermeasures to avoid the localized accumulation of corrosives successfully reduced the corrosion rate to a negligible level.