We know kero is blended as a pour point depressant in diesel in tanks, however will more kero in diesel by reduced stripping itself also affect the pour point in product diesel, considering flash point is not lowered too much?
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25/04/2020
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Eric Vetters, ProCorr Consulting Services, ewvetters@yahoo.com
Most strippers are operated to with the minimum amount of steam to remove enough H2S and light ends to meet corrosion and flash point specs. The actual amount of hydrocarbon that flashes in a stripper is relatively small. While theoretically stripping less will directionally lower pour point, from a practical standpoint, you would never be able to have much impact on pour point by reducing stripping steam before you ran into other spec problems .
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31/03/2020
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Sridhar Balakrishnan, Bharat Oman Refineries Limited , laksrid@yahoo.com
Kerosene is blended with diesel as a pour point depressant. It depends on process type and diesel type. Straight run diesel has high pour points , by blending kerosene it will have an effect on the pour point parameter i.e will act as pour point depressant . But the diesel cut obtained from hydrocracking or other process already has low pour points. Blending kerosene will have little effect on pour point, but it will increase diesel production.
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30/03/2020
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keith bowers, B and B Consulting, kebowers47@gmail.com
Diluting diesel with kerosene to lower the diesel pour point MAY be effective in specific situations. There is no 'pat answer' correlating amount of kero added to diesel lowering pour point by any fixed amount. The 'diesel' can fail the specification from two different causes or combinations thereof. Paraffin Wax crystals can form a lattice preventing the diesel from moving when the test tube is tilted horizontal for the specified time. The 'heavy end' of the diesel can become very viscous and likewise prevent diesel flowing when the test tube is tilted. In some 'wax caused' cases, precisely following the test method, checking the sample every 5 degrees by fully tilting the test tube horizontal for the entire specified time, disrupts a wax lattice, shearing the wax into micro-particles which will no longer congeal and inhibit to bulk fluid 'pour.' People, being inherently lazy, will sometimes not check the test sample every 5 degrees as specified and only look when the spec temp is reached. This allows the wax crystals to join in a 'mat' preventing apparent flow during the few seconds of tilting.
"Leaving' more kero in the diesel cut by 'reduced stripping' is unlikely to significantly lower the diesel cut pour point, as that characteristic is primarily due to N- paraffin wax content and/or 600-650F portion viscosity. Since the N-paraffin wax 'boiling point' is specific to the particular crude oil, without knowing the diesel cut wax characteristics, dilution with kerosene impact on the diesel 'pour point' can not be 'guessed.'
Test blends are necessary.
"Reduced Stripping' of the diesel cut effects both 'flash point' and H2S content and may result in failing corrosion tests. Even trace amounts of H2S will cause failure of the 'copper strip' corrosion test
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30/03/2020
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Jake Gotham, InSite Technical Services, jake.gotham@insitetechnical.com
Theoretically, there would be a benefit in terms of pour point from reduced stripping, but it is unlikely to be significant. Reducing stripping steam would have a larger impact on the IBP and 5% point than the rest of the boiling curve. Flash point correlates strongly with the IBP & 5% point, whereas pour point is more linked to the heavier half of the boiling curve. Hence I would expect you would be offspec on flash point before you had a measurable advantage in pour point.
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