relation between pen & viscosity

[gelpino]

Hi,
there's someone that can explain me something about blending,recutting, "viscosity blending number"(VBN) and evenctually if there's some kind of relation similar to "penetration=f(VBN,?)"or some info related to it?
Thanks a lot also for reply to a part of this long question.
Best regards.

 

[gelpino]

I point out that our problem is that having the VBN of an heavy blending we want to know the penetration of residue becouse at present our empirical relation is not good for all the oil we use in our refinery. I would glad any info about this.
Best regards.

gelpino

 

[jmw]

Some years back I read a paper by Shell which researched the relationship between PEN and Censtisokes, which is quite complex. This may not be a published paper and i could not find it in a brief search on the Shell web site so I would recomend you contact Shell directly and enquire about a copy.
PEN relates to a method of measuring the viscosity and is, as such, a historical measure. Viscosity is measured in the laboratory by alternative technologies such as the cone and plate viscometer which, with a density measurement, will enable the determination of the kinematic viscosity.

http://www.research-equipment.com

is the web site for a company specialising in cone and plate viscometers and who may have access to similar data.
Viscosity can be very efectively measured on line using digital viscometer systems which exploit the temperature viscosity relationship from ASTM D341. This gives the kinematic viscosity at reference temperatures. Some US users (referred to in the US as Asphalt)have declared the accuracy to be the equal or better than the laboratory (therefore presuming they have established this from a statistical evaluation of the laboratory results as per API 555 (or 554?) This method is used for blending control i.e. to control the addittion of cutter stock to the base stock. In blending control systems using dual viscometers the Viscosity index s also determined. In simpler applications using single viscometers the viscosity index is not available.
If you would like more information on process measurement, please let me know.

 

[TD2K]

I have an old reference from Chevron that shows the viscosity curves against temperature of 3 different asphalts (low, medium and high pen).

From that, you 'could' create a relationship. But, I don't work with asphalts to know for a specific pen, how much variation in viscosity there would be depending on the crude used to make the asphalt.

 

[gelpino]

Thanks a lot,
If u want share documents plz send to gelpino@yahoo.it.
Surely it would be interesting to find that shell paper or some similar reference. At this point I wish at least to know about theories useful for this study. Everything is glad.
Best regards


gelpino

 

[gelpino]

I have found a relation from an old work of "R.J. Saal" and another of Abushlhada (Ind.Eng. Chem. Prod. Res. Dev., Vol 18, No 4, 1979)in wich there are some relation penetration viscosity of asphalt. Similar to
V=[(1,59*10^10)/P^2.16]
for purely viscous asphalts (Newtonian)in agree with theoretically deduced formula
al + 0.5bl^2 = PT/V
with a =constant denoting the resistance of the penetration needle, and l= the depth of penetration in cm, and b =constant for needle resistance calculated to be 2,10 for needle standardized by ASTM, T duration of load in seconds, P penetration and V viscosity.
It's a starting point!

gelpino

 

[25362]

Penetration blending of similar bitumens, oxidized with oxidized, and not-oxidized with not-oxidized can be approximated by
log P_blend=a logA +(1-a)log B
a, b=1-a, are the proportions; A, B are the components' penetrations, respectively.

Semi-log graphs could be used with straight lines connecting the log ordinates. The linear abscissa has the w/w% of the components. Ditto for the blending of R&B Softening Points, ^oC.

A word of caution: best results are obtained by lab testing to determine the right proportions.

As to the viscosity limits associated with various applications:

For pumping, a maximum of 2000 cSt
For mixing processes, 150 to 300 cSt
For spraying, 50 to 200 cSt

 

[gelpino]

yes but if we bland vacuum residue with HVGO...of different crude (or bland of crude and fuel oil foer example)i think the situation is quite different

gelpino

 

[25362]

You are right. Thus the advice of doing it first in the lab.