During processing of high TAN crude oils in a crude distillation unit generation of organic acids can occur. At what minimum value of TAN can these organic acids be generated during processing? Is there any rule of thumb for this ?
Answers
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26/08/2020
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Eric Vetters, ProCorr Consulting Services, ewvetters@yahoo.com
There is no lower TAN limit. The amount of organic acid generated should be roughly proportional to the the TAN, assuming constant heater outlet temperature. There is some variation between crudes as far as the rate at which the naphthenic acids crack to lighter acids.
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17/08/2020
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sam lordo, Becht Engineering, salordo@comcast.net
if you are referring to the thermal degradation of high TAN crudes, that would be dictated by the time and temperature the crude or side stream is exposed and the MW of the particular naphthenic acid present. i have seen 10-15% degradation in vacuum tower processing (higher temps than crude tower operation).
One needs to remember that all acidic species are measured by the TAN test. It is not naphthenic acid specific, so even organic acids ( and other acidic species are measured), hence using TAN as the measurement method is not particularly useful in determining much more that if there was an increase of acid species
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17/08/2020
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Keng Chung, Well Resources Inc., kengchung@hotmail.com
In theory, the naphthenic acids and phenols in crude oil will transform into small molecular organic acids during distillation operation, which are highly corrosive (see Hydrocarbon Processing, December 2017, p. 85-86). This explains why adding corrosive inhibitors is ineffective to alleviate corrosion problems in a distillation unit for high TAN crude.
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