Estimation of Metal Loss by Corrosion Process in Heat Exchangers Applied to Hydrotreating Systems

摘要

It is well known that among of all the components of hydrotreating systems used in the industrialprocesses, the heat exchangers that pre-heat the reactor suffer the greatest degree of degradation bypitting corrosion due to extreme temperature exposure. Typically, two different mathematical analysiswere used to estimate the probability of failure by metal loss as a consequence of pitting corrosionmechanism: short-term and long-term corrosion rate (STCR and LTCR, respectively), as designated byAPI 510 standard method. However, the results are often misunderstood when the difference betweenthe calculated data of STCR and LTCR is large. For this reason, in this research the STCRs andLTCRs models were fitted to a generalized extreme value distribution (GEVD) to characterize themetal loss that take place in four heat exchangers, as well as to determine what kind of corrosion ratemodel is better for predicting the metal loss estimation. According to the results obtained in thisresearch, the STCR model appears to be the most appropriate analysis for estimating future metal lossby pitting corrosion for the heat exchangers reactors used in hydrotreating systems.