Pour Point Blending or Cold Flow Property Blending

[stevethermo]

Would anyone be able to share some information on the cold-flow-property blending methods, in particular the pour point blending method, that uses the pour point index? I am looking for an estimation method that was developed by Chevron. It seems to have been picked up in the Crude Assay software programs, with some older manuals showing the formulas for the indices but no details or references are given. Are the indices blended on a volume basis? mole basis?

I am wanting to predict how much of a light stream would be needed to improve flow, and pour point of a crude oil. I have heard that the Chevron methods work better than the other methods for fluids of widely differing properties. Any experience that you could share on this would be helpful.
Thanks,
SteveThermo

 

[jmw]

I don't know if it helps but I just looked into the fuel oil blending programs and find that the Exxon calculator includes pour point so when calculating blend properties it includes the calculation of the poiur point.
I couldn't use pour point as a blend target parameter so i had to increment my way toward the value I wanted by changing the viscosity target.
The Shell and DNV PS programs don't appear to include pour point.
If you want any of these programs they are free from the marine fuels department or you cpould find someone in the marine fuels department to advise you what the equation is that they use. (goto Exxon Mobil Marine Fuels website)

JMW

http://www.ViscoAnalyser.com

 

[25362]

When it refers to crude oils, PP measurements are covered by ASTM D 5853. There are a number of automatic tests, beside D 97/IP 15, for distillate fractions, with doubtful applicability to residual fuels. I don't know of their correspondence, accuracy, reproducibility or repeatability.

I am aware of the fact that they are a useful -although not an exact- guide to wax precipitation temperatures. This problem shouldn't appear at temperatures above the cloud point (D 2500/IP 219), which sometimes are 20[sup]o[/sup]F above the pour point if containing PP-depressing additives.

European countries adopted differing low-temperature operability (filterability) tests for diesel fuels (in the UK, the cold filter plugging point, CFPP).

Field results are apparently affected by the thermal history of the particular fluids and their viscosities, even the size and shape of the container and the hydraulic head may affect their flowing tendency in use. Storage of higher viscosity fuel oils in heated tanks (to reduce viscosities to pumpable levels) will apparently permit higher pour points than would otherwise be possible.

Laboratory bench tests are generally recommended to predict field results. When dealing with two or more fractions, blending indices are sometimes used as guidance, of course on a volume basis. Results aren't rigorous.

I don't know about the Chevron method. D.S.J.Jones' Elements of Petroleum Processing (Wiley) brings an example for a blend of gas oil and waxy distillate, the indices for which are determined from a semi-log graph as function of their individual pour points and 50% ASTM distillation points (I think of Kuwait cuts).