Organic Chlorides in Petroleum Crude Oil: Challenges for Refinery and Mitigations

Abstract

Crude oils contain chloride impurities, including some organic components termed as ‘organic chloride'. Owing to the high dissociation energy of the C‐Cl bond, organic chlorides are very difficult to remove during the desalting process unlike inorganic chloride salts. Failure to properly remove organic chlorides could have a significant adverse effect on petroleum refinery equipment in terms of corrosion during crude oil processing. Therefore, stringent specification of organic chlorides is being maintained throughout the refining process to avoid corrosion‐related incidents. Generally, a guard bed column is used for the removal of organic chlorides in the downstream of the refining process. Guard bed columns are comprised of metal oxide‐based components that operate at a very high temperature. In contrast, a phase transfer catalyst (PTC)‐based process for organic chloride removal at the upstream of the refining process is established up to lab‐scale and with model compounds only. This review is aimed to highlight the technical challenges associated with organic chloride contamination in refining processes and plausible methods and techniques available for smooth refining operations.

Effects of Fuel Hydrochloric Acid Contamination on Selected Metals

“…Hydrogen chloride is one of the most damaging chemicals in refineries [19], and under certain conditions, organic chlorides can generate hydrochloric acid [9,21,22]. Blending organic chloride-contaminated and uncontaminated crude oil is an economically feasible solution for refineries [23]. However, it should be noted that blending does not make the oil free from organic chloride contaminants.…”

“…A review by Mitra et al [23] gives an account of organochloride compounds contaminating crude oil. In one part of the refinery, organic chlorides had hydrolyzed and formed hydrochloric acid.…”

“…The second hydrolysis caused severe corrosion, and the low pH led to a leak in a carbon steel tube. The leak finally resulted in 60-80% of metal loss [23].…”

“…Organic chlorides can also generate hydrochloric acid under certain conditions [9,21,22]. According to Mitra et al [23], chloride-containing additives such as chloride-containing surfactants are added to assist extracting the oil. Therefore, it is possible that chlorinated organic compounds are found in fuels and that they can cause similar damages to vessels as in refineries through possible hydrochloric acid formation.…”

“…Refineries have set a limit of 1 ppm for organic chlorides [23,24]. The company Capline System has upper limits for organic chlorides, which are 1 ppm in whole crude and 5 ppm in 400 • F (200 • C) end-point naphtha cut [25].…”