For the last couple of weeks, ATF product ex Merox is failing on Silver Strip Corrosion test. What could be the reason?
Answers
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16/05/2011
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Sudhakara Babu Marpudi, Dangote Oil Refinery Company, m_sudhakarababu@yahoo.com
Caustic carry over could be the reason. Caustic absorbs H2S and can affect the Silver strip. Check the reasons fro Caustic carry over (is it because of higher thruput of ATF Merox which resulted in entrainment of Caustic from Caustic settler to water wash vessel and down stream). This caustic can be washed off in the wash water vessel. Normally the wash water is replaced only after certain predeided pH levels for reasons of water saving. If the water from the wash water vessel is replaced only at a pH of 10 earlier, try replacing the water at a max pH 9.0. If the salt dries is also contaminated with high pH water (due to previous practice) it will take time to correct the situation till the salt drier is free of such Caustic traces.
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06/05/2011
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Lindsay McRae, Pall Corporation, Lindsay_McRae@pall.com
Carryover of water with caustic traces from the Merox unit could possibly be the reason. Caustic is a strong surfactant and in caustic treaters, a stable emulsion with low interfacial tension (IFT) is often formed. It's a difficult emulsion to break but it's important to remove water and caustic to protect downstream processes and / or ensure product quality.
Some types of mesh pad coalescers, sand coalescers or electrostatic coalescers sometimes used to separate water & caustic downstream of the caustic treater & water wash are not fully effective. High efficiency PhaseSep Liquid coalescers can remove caustic in conjuntion with water wash.
What type of separation equipment do you have now? How much free water is being seen downstream of the existing equipment?
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04/04/2011
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keith bowers, B and B Consulting, kebowers47@gmail.com
The silver strip corrosion test indicates reactive sulfur in in the turbine fuel. Merox processing will not remove all forms of sulfur compounds. TRACE amounts of H2S will cause failure of the silver strip corrosion test.
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