We found a high TAN, ca. 0,4 mgKOH/g (usually 0,1), on a LCO cut.
What could be the explanation?
Answers
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05/09/2014
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Keng Chung, Well Resources Inc., kengchung@hotmail.com
I doubt that any oxygen containing compounds in the crude can survive the FCC reaction condition. Therefore, the acid compounds found in this LCO stream are not FCC derived products.
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04/09/2014
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Ralph Ragsdale, Ragsdale Refining Courses, ralph.ragsdale@att.net
A value of 0.4 would be considered high for the whole crude, if it is low sulfur crude, but not if it is high sulfur crude. In any case, neither 0.4 nor 0.1 is considered high in a gas oil fraction, and would be considered one and the same level, and not requiring a metallurgy solution.
The TAN analysis is not as accurate for detecting naphthenic acid content as other available test methods because the TAN method includes other acids as well, some of which are not corrosive.
At FCC units where “high TAN” crudes are processed in the crude unit, metallurgical protection is not required downstream of the feed heater tubes.
For comparison, at cokers, however, only one case of high TAN corrosion has been reported. In other words, vacuum resid normally contains no naphthenic acid that would cause corrosion in the coker.
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04/09/2014
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keith bowers, B and B Consulting, kebowers47@gmail.com
look back to the crude source. Some crudes contain naphthenic acids, some of which will show up in the LCO. This can be determined with a 'TAN' on the crude oil.
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