Fluorides in Naphtha

At a liquid cracker complex , fluorine compounds (hereafter: “fluorides”) were observed in single-digit ppmw levels in the pyrolysis gasoline (pygas), and in various naphtha feed cargoes which had been imported and already processed through the cracker complex without adverse effects noticed. Prior to this observation, awareness had existed regarding the threat of fluoride contamination from butane feeds, but the possible presence of measurable amounts of fluorides in naphtha feeds had not been expected previously. There is no maximum specification limit for fluorides in the Open-Spec Naphtha (OSN) quality parameters ordinarily used for naphtha trading, so fluorides in naphtha cargoes have not been measured or reported historically. The realization that fluorides could be present in naphtha cargoes prompted a technical review of the potential reliability & safety implications of fluorides in the cracker and in the pygas hydrotreating unit. In this paper & presentation, we provide an overview of some relevant considerations when assessing possible plant integrity concerns pertaining to fluorides, and more generally, halides (also including chlorine compounds), as feedstock contaminants.