Paraphinic & Naphthenic Crude Comparison

MaNaTMoS · Jul 26, 2004

Hello to members and visitors, I have one rather general question to ask, but I'm interested in every detail I can find out.
The question is about pour point values of vacuum distillation unit products: LVGO, HVGO, TGO (or stripped part of vacuum resid) and vacuum residue itself, from different crude oils - paraffinic and naphthenic one. Distillates from paraffinic crude are generally more "sticky", as we have found when processing these kinds of crude - condensers would become cold and filled with condensate, thereby dramatically reducing vacuum level in vacuum stripper and even promoting microbial growth in ejector system. I'm especially interested in ranges of pour point values (as a function of crude & distillate densities, P-N-A ratio, ATSM distillation, etc.)

Happy time and thanks in advance,
MaNaTMoS

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KazakhJeff · Jul 28, 2004

We run 100% Kazakh Kumkol crude, which is extremely paraffinic. Crude Pour Point varies between plus 3 and plus 20 Deg C, with a density range of about 0.87-0.92. Our crude tower bottoms Pour Point is approx 36-40 Deg C, with cut point approx 350 Deg C. The LVGO PP runs approx 38 Deg C, and HVGO PP runs about 50 Deg C. Combined is approx 48 Deg C, with EP approx 540 Deg C. VGO Density runs 0.86-0.88. Vac Resid density is approx 0.96, and PP approx 38 Deg C. We have no problems to process, but have problems with storage in winter, when the waxes tend to deposit out. If designed properly, shipment by rail tank car, and discharge, is also no problem.
Hope this helps. Please let me know if you need any more specifics.

MaNaTMoS · Jul 28, 2004

Dear Jeff, thank you for your reply.

Crude assays and API tables represent good source for this kind of information, but I was looking for something else, actually. Are there any ways to calculate and predict pour point values for different products/fractions, based on API gravity/ASTM distillation, KW-factor, viscosity, etc.? I'm asking this in order to find out possible opportunities and limits for blending different crude oils, without risk of plugging condensate draining system in VDU when processing these crude oil blends?

phex · Jul 28, 2004

sadly, i can't really help you. but i have one hint for you: spiral software is marketing a product called "crudemanager" which has algorithms to estimate crude parameters from just the distillation curve. the predictions quite often fit our lab data, so they seem to have quite something there. one way would be to use their program, but its costs are enormous, especially if you also buy a crude library with it. i think i'm not really allowed to tell the prices, but its more than 20000 euro per year for the simplified LE version (this is without the prediction algorithms as we don't need them) with a small crude library (around 300 crudes).

they will probably not tell you how they calculate, but perhaps it is worth a try to ask.

hth,
chris

25362 · Jul 28, 2004

When confronting an issue as the one presented by MaNaTMoS, the procedure used by refiners I was connected with, was to run in the lab various mixes and observe the results on the fractions of interest. Sometimes the vacuum cuts obtained in those assays were passed over to an attached lube-and-wax refinery lab for further assessment. [smile]

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