Any refinery experience with mercury contaminated crude oil processing from corrosion point of view?
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16/02/2015
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sam lordo, Becht Engineering, salordo@comcast.net
Mercuric chloride is the typical corrosive of concern in crude units.. cs, 316ss, 304ss are all un acceptable materials; mercury also acts as a accelerator for corrosion
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16/02/2015
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Lindsay McRae, Pall Corporation, Lindsay_McRae@pall.com
Hg often follows naphtha cut and LPG. Aside from issues with catalyst deactivation in ISOM or NHT units, and/ or off spec naphtha cracker feed, Hg in LPG is a big potential safety issue for aluminium fin heat exchangers which may be used in LPG service. Liquid Mercury Embrittlement (LME) is well known to cause catastrophic failure in aluminium heat exchangers. LME is difficult to predict and monitor and several fatalities have occurred over the years due to catastrophic heat exchanger failure.
Mercury guard beds can be used to remove Hg down to <1 ppb and Hg bed life can typically be upto 2 years between bed replacement however care should be taken to also protect the Hg guard bed from fouling due to water and particle contamination in the LPG / naphtha feed. High efficiency PhaseSep LL coalescers and pre-filters are commercially used to protect Hg Guard beds with good results.
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15/02/2015
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Eric Vetters, ProCorr Consulting Services, ewvetters@yahoo.com
I was involved mainly from the R&D side. We never identified any actual mercury problems at any of the refineries in my former company's refining system. The concern was primarily with aluminum and I believe, some alloys containing copper. The aluminum only tends to be around if you have a cryogenic gas processing plant in the aluminum plate fin exchanger. Not many refineries have those units though. Monel in the crude overhead system would probably be the biggest area of concern or brass water cooler bundles, but I have never seen a real problem in these components and don't remember anything being reported at NACE.
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