Calculate the cloud point of a crude blend?

[jmw]

When blending two different crudes, is there a calculation that may be used to determine the cloud point of a blend based on the cloud points of the original crudes?

Alternatively, is there a relationship between the density and viscosity of a crude blend and its cloud point? e.g. something like the Viscosity Gravity Constant calculation....

The object is to determine the cloud point of the crude as it is being blended.
We have available the volume ratios of the component crudes and the density and viscosity (at process and reference temperatures) for the blend and can have them also for the component streams.

JMW

http://www.ViscoAnalyser.com

 

[0707]

on page 20 of the document bellow maybe you find some help

http://energyinst.org.uk/content/files/hm40.pdf

luismarques

 

[25362]

Interesting question. Regarding cold properties, and according to ASTM, cloud points are measured on fluids that are transparent in layers of 4 cm. Crude oils are "black". What could be the incentive to predict a cloud point on black fluids ?

 

[SeanB]

I was going to ask the same question - why would you be concerned about the cloud point of a crude? I don't even know if you can measure such a thing. Normally, we are only concerned about cloud points of finished products i.e - diesel.

 

[jmw]

Thanks for the prompt replies.
I haven't been advised by the client's end user of why but I suspect that it may relate to pipe line operations once the crude has been blended. In my internet search before I posted the question I found some reference to this being about the main reason why pour point and cloud point of crude would be of interest and yes, the problem of opacity is one reason why we want to arrive at this information indirectly or through calculation.
Waxing is a frequent problem with pipeline metering and with some online measurements. Interestingly, one paper comments on the problems of predicting viscosity at temperatures close to the cloud point. Another suggests a link between cloud point and pour point and illustrates with a graph of pour point against cloud point.
Thanks for the link 0707, I found this document on the MEPC data base (Marine Environmental protection Committee part of IMO)

JMW

http://www.ViscoAnalyser.com

 

[jmw]

Ah,
can only now find the amendment to this doc which is

http://www.imo.org/includes/blastDataOnly.asp/data_id=15683/81(43).pdf

But no matter, the doc that 0707 refers to shows several methods including one where cloud point is derived from the pour point but of most interest is the blending index method. Thanks.

JMW

http://www.ViscoAnalyser.com