The color of Gas oil produced from Mild hydrocracker is off spec. After changing the catalyst and the feed blend. The new feed blend includes 20% of Aromatic extract and VGO in feed blend was reduced by the same %. What are the reasons of gas oil color changing? is feed tank required to be blanket with Nitrogen?
Answers
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25/05/2019
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keith bowers, B and B Consulting, kebowers47@gmail.com
'Aromatic extract' typically contains much more complex molecules, many with C=N and C=O bonds in those molecules. These molecular bonds ABSORB light at many frequencies and the 'color' test measures the un-absorbed residual light when white light is passed through the sample. Removing the 'color darkening' molecules usually required more severe hydro-treating, either with a more active catalyst, higher temperature,higher hydrogen partial pressure.
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25/12/2018
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Sridhar Balakrishnan, Bharat Oman Refineries Limited , laksrid@yahoo.com
Reasons for colour changes may be due to basic nitrogen compounds left in the hydrocarbon. Also colour precursors are always associated with hetero compounds of the hydrocarbons. Aromatic extract of feed blend could be one of the contributor for colour degradation during storage for the gasoil.
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